PROCEEDINGS

of the Tomsk Technological Institute

of Emperor Nicholas II.

Vol. 16. 1909. No. 4.

I.

P. A. Kazansky.

MATERIALS FOR THE STUDY OF THE FAUNA OF THE JURASSIC DEPOSITS OF DAGESTAN.

With 3 plates of phototypes.

1–116.

The material for the present work was a collection gathered by me during a month’s stay in Dagestan in the summer of 1903. In this article I describe only the part of this collection that belongs to the Jurassic system; the greater part of the fossils collected by me belongs to the Cretaceous system, chiefly to the lower division of the latter. I was prompted to describe separately the very small Jurassic collection not only by the general delay in the work caused by the events of recent years, but also by the circumstance that, as it seems to me, my results introduce a substantial correction into the understanding of the general section of the Dagestan Jurassic that has become established in recent years (see Renz, “Der Jura von Daghestan,” in “Neues Jahrbuch für Mineralogie etc.” for 1904, II B. S., pp. 71—85). This correction, however, is not something new, but simply represents a return to the old point of view of Sjögren and Abich.

Being compelled to write my work in Tomsk, I naturally did not have at hand all the necessary literature, and therefore must state in advance that in this respect there will undoubtedly be gaps in my work: almost nowhere could I give the complete synonymy of the species I cite, and I think there will also be gaps in the comparative-stratigraphic part of the work. Having no possibility of achieving completeness in this respect, I prefer not to strive for it, limiting myself only to what seemed to me necessary and essential. In the synonymy of species, for example, I included only those works available to me that I used in making determinations, or that gave indications important for me concerning the distribution of one or another of the forms described by me.

I must express my gratitude to the Kazan Society of Naturalists for the funds with which it supplied me for the collection of the material that served as the basis of my work.

I.

HISTORICAL SKETCH.

In the present sketch I do not undertake to exhaust all the literature on the Dagestan Jurassic, since I cannot do so while living in Tomsk. Its purpose is only to show how our present knowledge of the Dagestan Jurassic was formed.

The existence of Jurassic deposits in Dagestan was noted already by Dubois de Montpéreux and on Murchison’s geological map. However, the concrete acquaintance of the scholarly world with them began only with the work of Abich. The results of his investigations were published by him in a series of articles (the most important: “Verzeichniss einer Sammlung von Versteinerungen von Daghestan mit Erläuterungen” in “Zeitschr. d. Deutsch Geolog. Gesellsch.” Bd. III, S. S. 15—48 and Taf. I—II, and “Vergleichende Grundzüge der Geologie des Kaukasus wie der Armenischen und Nordpersischen Gebirge nebst 8 Tafeln” in “Mémoires de l’Académie Impériale des sciences de Saint-Pétersbourg,” VI Série, Sciences Mathémat., physiques et naturelles, tome IX, p. p. 359—534).

A summary of these results and, together with it, the first complete description of the stratigraphic relations of Dagestan, Abich gave only in 1862 in the article “Sur la structure et la géologie du Daghestan” (in “Mémoires de l’Académie des Sciences de S—t Pétersbourg”; VII Ser. tome IV No 10).

In this article Abich distinguishes three stages (étages) in the Dagestan Jurassic.

c. The upper stage in its upper part consists of limestones and dolomites. These limestones are siliceous and saccharoidal, often contain siliceous concretions, and sometimes become breccia-like. Among the dolomites gypsum is encountered. Fossils are numerous and consist of casts of Nerinea, Ostrea, Terebratula.

Beneath these limestones lie either dense gray marly limestones, well bedded, or impure clayey-ferruginous and sandy limestones with numerous petrifactions: “Ammonites coronatus, canaliculatus, Ceromya excentrica, etc.” These limestones form a well-defined horizon almost throughout all of Dagestan.

b) The middle stage consists of sandstones, to which clay shales and dark marls are subordinate. Among these shales and marls there occur concretions with ammonites. In the sandstones and shales of the upper part of this stage, remains of plants are encountered, sometimes passing into small deposits of coal.

a. The lower stage consists of clay shales and sandstones without organic remains, except for impressions of algae.

It should be mentioned that a list of Jurassic plants from the Uluchai valley in Dagestan is given by Abich in his earlier article (“Vergleichende Grundzüge etc.” pp. 472–479; see above), where he stratigraphically places these plants in the very uppermost Jurassic, at the boundary with the Cretaceous system, although the character of the flora rather compels one to accept a Middle Jurassic age for them.

In the article under discussion, Abich already categorically assigns these plants, as well as all the coal-bearing deposits of Dagestan, to the Middle Jurassic.

After this outline by Abich, the study of the Dagestan Jurassic long underwent no substantial additions. Only in 1889 did Kj. Sjögren publish a new general outline of it: “Uebersicht der Geologie Daghestans und Terek-Gebietes” (“Jahrbuch der Kais.-Königl. Geologischen Reichsanstalt,” vol. XXXIX, pp. 417–458). The general section given by him differs little from that given by Abich, but supplements the latter with certain details.

Sjögren distinguishes, from top to bottom:

1. Kimmeridge and Corallian.

a. Dense dolomitic limestones of a darkish color, sometimes breccia-like or porous, with geodes filled with scalenohedra of calcite.

Cerinea, Diceras, Terebratula.

b. Dense bituminous dolomites and limestones with pink and white alabaster.

1. Oxford and Callovian.

a. Gray limestones and dolomites with dark segregations of flint and chalcedony.

b. Gray marly limestones with numerous ammonites: Harpoceras lunula, Peltoceras athleta, Stephanoceras macrocephalum.

c. Banks of ferruginous clayey sandstone, yellow in color, usually friable, passing downward into shaly clay.

1. Bathonian and Bajocian.

A thick series of dark, gray, greenish thin-shaly marls and shaly clays, with subordinate calcareous concretions: Harpoceras opalinum, Harpoceras Murchisonii, Stephanoceras Humphresianum.

1. Lias.

Thick variegated calcareous sandstones, in the lower parts interbedded with dark clayey layers. Coal and impressions of plants.

The difference from Abich’s scheme consists, apart from the greater detail of Sjögren’s scheme, in the fact that the Dagestan coals here are taken to be Liassic and are placed at the base of the Jurassic system, whereas Abich assigned them to the Middle Jurassic.

In 1892 there appeared the principal work on the Jurassic fauna of the Caucasus, containing a description of Abich’s collections preserved in Vienna. This is the work of Neumayr and Uhlig, entitled: “Über die von H. Abich im Kaukasus gesammelten Jurafossilien.” (“Denkschriften der Kais. Akademie der Wissenschaften”; Vol. 59; pp. 1–112). The stratigraphic part of the work is taken from Abich and Sjögren and is supplemented only by more detailed determinations of age on the basis of the organic remains described by the authors.

From the upper part of Abich’s upper stage (c), only Pholadomya could have come from the collection studied by the authors, very similar to Ph. gigantea Sow., i.e., to a Neocomian form.

From the lower part of the upper stage (clayey limestones with numerous petrifactions), the authors describe the following forms:

1. Perisphinctes polyplocus auct.
2. Perisphinctes Abichi Neum.
3. Perisphinctes n. sp. ind.
4. Perisphinctes sp. ind.
5. Reineckia anceps Rein.
6. Stephanoceras coronoides Qu.
7. Harpoceras n. sp. aff. semifalcatum Opp.
8. Harpoceras Daghestanicum Neum.
9. Harpoceras sp. aff. punctatum Stahl.

1. Harpoceras punctatum Stahl.
2. Phylloceras sp. ind.
3. Phylloceras sp. ind.
4. Pholadomya exaltata Ag.
5. Pholadomya hemicardia Roem.
6. Pholadomya anomala Neum.
7. Ceromya excentrica Voltz.
8. Pleuromya cf. Alduini Brug.
9. Gresslya abducta Phill.
10. Modiola Villersensis Opp.
11. Pinna mitis Phill.
12. Inoceramus cordati Uhl.
13. Pecten fibrosus Sow.
14. Pecten cf. inaequicostatus Phill.
15. Rhynchonella varians Schl.
16. Terebratula sphaeroidalis Dav. var. Balinensis.
17. Terebratula bissufarcinata Schl.
18. Terebratula sp. ind.

On the basis of the presence of: Reineckia anceps, Stephanoceras coronodes, Harpoceras punctatum, Pinna mitis, Terebratula sphaeroidalis var. Balinensis and Rhynchonella varians, Uhlig establishes the presence in this thickness of Callovian deposits.

The presence of Harpoceras n. sp. aff. semifalcatum, Harpoceras Daghestanicum, Modiola Villersensis, Inoceramus cordati indicates, in Uhlig’s opinion, the Oxfordian stage, and

Perisphinctes polyplocus, Perisphinctes Abichi, Ceromya excentrica,

the Kimmeridgian stage.

In addition, Pholadomya hemicardia is an Oxfordian–Kimmeridgian form.

Hence the impure bedded limestones forming the lower part of Abich’s upper stage (c) must, according to Uhlig, represent the Callovian, Oxfordian, and Kimmeridgian stages.

The middle stage (b) of Abich, from which the authors describe 25 species, Uhlig correlates with the Bathonian and Bajocian stages, while the underlying sandstones he partly regards as Lias.

In 1895 there appeared the work of Barbot de Marny: “Report on the investigation of the mineral resources and geological structure of Dagestan.” Part I: Northwestern Dagestan (“Materials on the Geology of the Caucasus”; series 2, book 9, pp. 229—286).

The scheme of the Jurassic deposits of southeastern Dagestan given by the author is connected only to a very slight degree with the works of previous investigators and contains very little paleontological data, since the author’s attention was focused chiefly on the character of the occurrence of the rocks and of the useful minerals. The author distinguishes:

Upper division = Kimmeridgian and Oxfordian stages, consisting of dolomites and sandstones, occurring from top to bottom in the following order:

Porous dolomitic breccias.

Smoky-gray dense dolomites, divided by interbeds of gray sandy marl.

Yellowish-gray sandstones, more often clayey, more rarely calcareous, divided by interbeds of dark-gray sandy marl.

The thickness of the upper division of the Dagestan Jura is determined by the author at 130 sazhens. It is characterized by bedded deposits of alabaster and sulfur deposits. Fossils are common only in the breccia-like dolomites, but are poorly preserved, and from them the author cites only Terebratula sp. and Diceras sp.

Middle division = Bathonian and Bajocian stages, consists of shaly rocks and weakly bedded sandstones, occurring in the following order:

Shaly, clayey, and sandy marls of dark-gray and brown color, passing into dark thin-bedded clayey sandstones. Ferruginous concretions.

The same rocks, but with sandstones predominating.

The same rocks, but again with marls predominating. Ferruginous concretions with ammonites: Harpoceras opalinum.

Lower division = Lias, contains from top to bottom:

Yellowish-gray sandstones.

Clayey shaly marls.

Looser clayey sandstones. Plant remains. Coals.

Black shaly marls.

Clayey shales.

The principal positive result of this work for the stratigraphy of the Dagestan Jura is the determination of the position of the Dagestan coals, in which the schemes of Abich and Sjögren differed.

In 1898 L. Spendiaroff published a short article under the title: “Ueber einige Seeigel aus dem Jura des Kaukasus” (“Beit-

...träge zur Geologie und Palaeontologie Oesterreichs-Ungarns und Orients”; vol. XI; pp. 199–206), containing a description of several sea urchins from Abich’s collection, as studied by Neumayr and Uhlig. This article contains no new stratigraphic considerations on the Jurassic of Dagestan and, in its stratigraphy, follows Uhlig entirely.

In 1899 an article by Anthula was printed, containing a description of Cretaceous fossils from the collections of Abich and Sjögren (“Ueber die Kreidefossilien des Kaukasus,” “Beiträge zur Geologie und Palaeontologie Oesterreichs-Ungarns und Orients”; vol. XII; pp. 53–159). This article (pp. 129–146) also contains a general outline of the sedimentary deposits of the Caucasus; but, as regards the Jurassic, this outline is based wholly on Uhlig and Sjögren, and does not even note their mutual contradictions.

The short reports on the excursions of Prof. Stuckenberg and Prof. Andrusov (Stuckenberg: “A Journey to the Caucasus,” “Scientific Memoirs of the Imperial Kazan University,” year LXVIII (1901), book 3, pp. 105–116; Andrusov, “A Journey to the Caucasus in 1898,” “Zemlevedenie,” 1901, books I–II) contain no new results.

The work by K. Bogdanovich, printed in 1902, “Two Crossings of the Main Caucasus Range,” contains only a certain number of particular facts relating to the Jurassic deposits of southern Dagestan. I shall have occasion to return to some of them in the concluding part of the work.

In 1904 there appeared a very important, though small, work by Renz: “Der Jura von Daghestan” (“Neues Jahrbuch für Mineralogie, Geologie und Palaeontologie,” 1904; vol. II; pp. 70–85), almost simultaneously with a short report by the same investigator (“Monatsberichte der Deutschen Geologischen Gesellschaft,” 1904, no. 9; pp. 168–171). This work contains an attempt to give a new scheme for subdividing the Dagestan Jurassic, which differs rather strongly from the results of the older authors. This scheme is in part very detailed and reduces to the following:

The Malm, above the Callovian stage, is represented by light-colored limestones and dolomites with Virg. dorsoplanatus Vischn.

The Callovian contains 4 zones:

The zone with Card. Lamberti consists of grayish shaly sandstones with interbeds of sandy limestone. The author cites no fossils from here and places a question mark beside this zone.

The zone with Pelt. athleta is likewise represented by sandstones, partly yellow in thick beds, partly gray and shaly. From here the author cites only Perisphinctes Orion Opp.

The zone with Cosmoceras Jason is represented by black shales with concretions. From here: Stephanoceras coronatum Brug. and Harpoceras lunula Zieth.

The zone with Macrocephalites macrocephalus is represented by the same shales, with Harpoceras hecticum Rein. At times sandy interbeds are observed here in the shales.

The Bathonian stage contains 2 zones and consists of the same shales, above sometimes with sandy interbeds; below, the shales sometimes acquire a sandy and marly character. From

the zone with Oppelia aspidoides the author cites Perisphinctes Moorei Opp. From

the zone with Parkinsonia ferruginea is cited Parkinsonia ferruginea Opp.

The Bajocian stage consists of the same shales, sometimes with beds of sandstone.

The zone with Parkinsonia Parkinsoni contains: Parkinsonia Parkinsonia Sow., Parkinsonia densicosta Qu., Parkinsonia Schloenbachi Schlipp., Parkinsonia neuffensis Schloenb.

The zone with Stephanoceras Humphriesianum contains: Stephanoceras Humphriesianum Sow., Stephanoceras Braikenridgi Sow., Stephanoceras linguiferum d’Orb., Belemnites giganteus Schl. and many other forms.

The zone with Sphaeroceras contractum contains: Sphaeroceras contractum Sow., Sphaeroceras Sauzei Sow., Sphaeroceras Gervillii Sow., Stephanoceras Bayleanum Opp.

The zone with Hammatoceras Sowerbyi contains: Harpoceras cornu Buckm., Harpoceras concavum Sow., Sonninia Helenae Renz.

The Lower Dogger consists of black shales.

The zone with Harpoceras Murchisonae contains Harpoceras Murchisonae Sow.

The zone with Harpoceras opalinum contains Harpoceras laeviusculum Sow. and Hammatoceras sabinsigne Opp.

The Upper Lias is also represented by black shales. The author considers it possible to distinguish in it 3 zones: with Lytoceras Jurense, Hildoceras bifrons and Hildoceras serpentinum, but cites only, from the lower zone, Hildoceras serpentinum Rein.

The Middle Lias consists of mica-bearing argillaceous shales with locally sandy interbeds. From it only Cardinia cf. philea has been recorded.

The chief result of Renz’s work is a detailed subdivision of the lower part of the Dagestan Mountain and the presentation of a large list of forms newly found by him in the Bajocian and Bathonian stages. As regards the general subdivision of the Jurassic deposits of Dagestan, he departs markedly from the older authors: his lower, weakly sandy shale series embraces the whole Kellaway, and the so-called “geodenterrain” (shales with concretions) composes the whole middle part of the Mountain, the lower and middle Kellaway and the Upper Lias.

In the same year, 1904, I published a preliminary report on my journey of 1903. Touching in it only upon the upper part of the Dagestan Mountain (P. Kazansky: “Preliminary report on a geological excursion in Dagestan in the summer of 1903,” No. 232 of the “Appendices to the minutes of the meetings of the Society of Naturalists at the Imperial Kazan University”), I indicated therein that above the shaly-sandy lower series near the aul of Tsudakhar and the village of Gunib there occur marly limestones with a large Kellaway fauna, and that above these limestones lie purer limestones with a fauna consisting of sponges, corals, brachiopods, and a small number of mollusks. This limestone series, according to my supposition at that time, should probably represent the entire Upper Jurassic, beginning with the Oxfordian stage. This result agrees completely with Sjögren’s scheme and with Abich’s data, while diverging thereby from the results of more recent authors, beginning with Uhlig.

In 1906 there appeared the work of K. Bogdanovich: “The System of the Dybrar in the Southeastern Caucasus” (“Transactions of the Geological Committee,” new series, issue 26). This work contains interesting data on the fauna of the Jurassic deposits of the village of Gentshe in the valley of the Samur (southern Dagestan). These data are especially curious in that the Bajocian Harpoceras concavum Sow. is encountered here higher than the Kellaway Harpoceras punctatum and lunula, and partly together with the latter. This circumstance is important because, on the finding of Harpoceras lunula Renz, he partly bases his assignment of part of the Dagestan “geodenterrain” to the Kellaway.

Finally, in 1907, volume III of the large work by Moriz von Déchy, “Kaukasus,” was published. In this volume are collected geolo-

…graphic and paleontological results of the author’s investigations. The geological sketch, belonging to Dechy himself, gives nothing essential for knowledge of the Daghestan Jurassic, but the paleontological section, belonging to Papp, contains interesting lists of fossils, which partly help to make sense of the contradictory schemes of various authors. I cite these lists in full, since they relate to the Daghestan Jurassic.

1. Sandstone by the iron bridge near Gunib.

2. Holectypus cf. oblongus Wright.

3. Pleoroutomaria semiornata Stol.

4. Heteropora conifera Lmx.

5. Sandstone (Malm) beside the iron bridge above Gunib.

6. Turbo capitanus Lor.

7. Alectryonia hastellata (Schl.) Qu.

8. Alectryonia solitaria Sow.

9. Sandstone (Malm) of Karadag on the road to Gunib.

10. Collyrites cf. Desoriuna Cott.

11. Pholadomya hemicardia Roem.

12. Upper limestone bed of Gunib.

13. Pholadomya Schafarziki n. sp.

14. Pholadomya cf. asiatica Bexdl.
15. Myacites sp.
16. Ceromya excentrica Ag.
17. Pecten cf. Laurae Etall.
18. Pseudodiadema cf. subpentagona Laube.
19. Terebratula cf. Philipsi Mors. et Dav.

20. Rhynchonella cf. Royeriana d’Orb.

21. Gray sandy calcareous marl at the foot of Mount Gunib.

22. Cosmoceras Jason Rein.

23. Reineckia anceps Rein.
24. Ammonites calloviensis Sow.
25. Ammonites Chauviniianus d’Orb.
26. Peltocerus Athleta Phill.
27. Peltoceras Arduennense d’Orb.
28. Perisphinctes Abichi Neum.
29. Ceromya excentrica Ag var. nov.
30. Pholadomya paucicosta Roem.
31. Pecten inaequicostatus Phil.

1. Vola sp. ind.

2. Modiola cf. Caucasica Redl.

3. Lower beds (Callovian) near the railway bridge at Gunib.

4. Anisocardia sp. ind.

5. Terebratula subcanaliculata Opp.
6. Terebratula cf. Fleischeri Opp.

7. Rhynchonella spathica Lam.

8. Beneath the dark shales, Mount Gunib (Dogger).

9. Parkinsonia Parkinsoni Sow.

10. Parkinsonia ferruginea Opp.
11. Parkinsonia Ujbányáense Böckh.
12. Parkinsonia Schloenbachi Schlippe.
13. Stephanoceras linguiferum d’Orb.
14. Perisphinctes sp. aff. Martiusii d’Orb.
15. Perisphinctes Lóczyi Papp.
16. Perisphinctes daghestanicus Papp.

17. Lytoceras Linneanum d’Orb.

18. Khatary Valley south of Archi. Dark shale (Upper Lias).

19. Harpoceras lympkarum Dum.

20. Avicula Delia d’Orb.
21. Modiola sp. ind.

22. Mytilus sp. ind.

23. Samur Valley between Akhty and Kakhtoy. Dark limestone (Lias).

24. Pentacrinus sp. ind.

25. Gunshchuda Pass (region of the Samur River). Brown sandy shale (Middle? Lias).

26. Gervillia cf. crenulata Qu.

I give these lists because I shall need them later for comparison.

As a result, we see substantial contradictions in the parallelization of the Dagestan Jurassic among individual investigators. The present work represents an attempt to resolve one of these contradictions with regard to the area near Gunib and Tsudakhar (Dargin District), namely to determine the stratigraphic significance of that marly-limestone horizon which Abich took as the basis of his upper stage of the Dagestan Jurassic. As is evident from the foregoing:

Sjögren regards this horizon as Kellovian.

Uhlig regards it as the aggregate of the Upper Jurassic from the Kellovian through the Kimmeridgian inclusive.

Renz places its base no lower than the Upper Kellovian.

II.

On the Localities of the Described Fossils

The fossils described in the paleontological part of this work were collected in three localities.

I. Near the aul Tsudakhar in the Dargin district.

To the north of the aul, the road leading from Khodzhal-Makhi to Kazikumukh crosses the axis of a syncline composed of Upper Cretaceous rocks. Opposite the aul itself, as one approaches the nearest anticlinal axis, the Upper Cretaceous deposits are replaced by Lower Cretaceous ones, and about \(1/3\) verst south of the aul by Jurassic deposits. For these latter I recorded the following section.

Db. Whitish limestone with Ctenostreon sp., Ostrea sp., Terebratula subsella Leym., Cidaris sp.

Da. Gray limestone with Terebratula subsella Leym.

Cc. Crystalline limestone with gypsum and Terebratula bissufarcinata Schl. sp. and Rhynchonella moravica Uhl.

Cb. Gray limestone with siliceous concretions and traces of sponges.

Ca. Greenish limestone with Pecten fibrosus Sow., Gervillia aviculoides Sow. sp., Rhynchonella varians Schl. sp.

Bb. Gray marly limestone with interbeds of the same gray clay and numerous Middle Jurassic fossils.

Ba. Talus.

Ac. Marly and sandy limestone of yellowish and reddish color, in places with pebbles, with Cosmoceras macrocephali n. sp., Macrocephalites macrocephalus Schl. sp. and other Callovian species.

Ab. Clayey shales with an interbed of compact marl.

Aa. Clayey shales rarely with marly concretions. Mytilus sp.

II. Gunib. Here I did not manage to record the section. The greater part of the fossils was collected by me in the same greenish limestone as the Ca at Tsudakhar.

Its fauna contains both Upper Callovian (Peltoceras athleta Phill. sp.) and Middle Callovian (Cosmoceras Gulielmi Nik.) elements.

From the Upper Jurassic limestones I obtained only Rhynchonella cf. concinna Sow. sp.

From concretions of the Middle Jurassic, only Parkinsonia Parkinsoni Sow. sp.

Prof. Stuckenberg delivered from the Gunib Jurassic 5 species. The rock in which Astarte undata was preserved resembles the limestone in Tsudakhar; Perisphinctes subtilis Neum., in its preservation, recalls ammonites from the limestone Ac of Tsudakhar. Cyathophora Bourgueti Defr. sp. and Cyathophora Stuckenbergii n. sp. probably come from the Upper Jurassic limestone.

III. Along the road from Khodzhal-Makhi to Tsudakhar I found two ammonites, which in preservation resemble fossils of the limestone in Tsudakhar; they were identified as Erymnoceras Renardi Nik. sp., Perisphinctes indicus Siem.

III.

PALEONTOLOGICAL PART.

MOLLUSCA.

CEPHALOPODA.

Belemnoidea.

Family Belemnitidae.

Genus Belemnites. Lister. 1678.

1. Belemnites cf. calloviensis. Oppel. 1857.

1. Belemnites semihastatus depressus. Quenstedt. Cephalopoden;
   S. 440; Taf. 29, Fig. 12—19.

1856—1858. Belemnites calloviensis. Oppel. Die Juraformation;
S. 546.

1. Belemnites semihastatus depressus. Quenstedt. Der Jura;
   S. 547; Taf. 72, Fig. 14.

2. Belemnites cf. calloviensis. Lahusen. Ryazan Jurassic; p. 42;
   Pl. III, figs. 26—27.

A fragment of the anterior part of the rostrum, similar to Bel. calloviensis in the transverse section, flattened in the dorso-ventral direction, and in the grooves.

Locality: Tsudakhar; Middle Callovian limestone (Bb). Distribution: Middle Callovian—zone with Reineckia anceps (Brauner Jura ζ) of Swabia (Oppel, Quenstedt); Middle Callovian (horizon with Perisphinctes Mosquensis) of Ryazan Province (Lahusen).

2. Belemnites sp.

Fragment of a large phragmocone with an angle of about 35°. I consider the species indeterminable.

Locality: Tsudakhar; Middle Callovian limestone (Bb).

3. Belemnites sp.

Fragment of a rostrum of conical form, with a very large relative angle of the cone aperture and a very short axis. Both characters might correspond to Belemnites quinquesulcatus Blainville (Mémoire sur les Bélemnites; p. 83; pl. 2, fig. 8) from the Jurassic limestone of Mézières and England. The state of preservation, however, does not permit one to ascertain the presence of the characteristic furrows, and the stratigraphic position makes this species quite improbable.

Locality: Tsudakhar; limestone with siliceous concretions (Cb).

Ammonoidea.

Pachycampyli.

Cosmoceratida.

Fam. Cosmoceratidae.

Genus Cosmoceras. Waagen. 1869.

This genus is represented in my material by seven species. Of interest is the presence in it of 3 species with a broad, flat, ribbed siphonal side and with very weakly expressed or altogether absent siphonal tubercles. These characters, apparently, are peculiar only to individuals that have reached a certain age, and recall the rounded stage of the genus Kepplerites Neumayr (Jurafossilien von Kaukasus; pp. 53—57).

The lateral and umbilical tubercles that are preserved, although not always entirely distinct, distinguish these species from true Kepplerites. In addition, the young whorls that I was able to observe in one of my species bear the character of a typical Cosmoceras, and not Parkinsonia, as in Kepplerites. It is possible that such a stage will prove much ...

more widespread in Cosmoceras, since for many species of this genus only individuals of small size have been described. The fate of the genus Kepplerites in the scientific literature has proved somewhat strange. At least in the English edition of Zittel’s well-known textbook of paleontology (Zittel. Textbook of Palaeontology, p. 587), Hyatt apparently gives the same genus a new name, Sigaloceras.

In the classification of the genus I adhere to Teisseyre’s system (Sitzungsberichte der kais. Akademie der Wissenschaften, vol. 88), i.e., I do not separate the genus Kepplerites or Sigaloceras, since the characterization of Kepplerites in Neumayr is apparently inapplicable in the present case, and the genus itself may prove to be unnatural; while Hyatt has not yet given any characterization for his Sigaloceras.

Group Cosmoceras Gulielmi Nik. (non Sow?).

4. Cosmoceras Pollux Rein. sp. 1818.

1. Cosmoceras Pollux. Neumayr. Ornatenthone v. Tschulkowo; S. 343; Tab. 25, Fig. 5—6.

2. Ammonites aculeatus. Trautschold. Ergänzung z. Fauna Russ. Jura; S. 92; Taf. VII, Fig. 18.

3. Cosmoceras Pollux. Nikitin. Rybinsk; p. 99; pl. 10, figs. 36—37.

4. Cosmoceras Pollux. Lagusen. Ryazan Jurassic; p. 61; pl. VIII, figs. 5—9.

5. Cosmoceras Pollux. Teisseyre. Rjäsan; S. 578; Tab. IV, Fig. 26—27.

6. Cosmoceras Pollux. Nikitin. Yaroslavl; p. 71.

1886—87. Ammonites ornatus (pars). Quenstedt. Ammon. Schwäb. Jura; Tab. 84, Fig. 19.

1. Cosmoceras Pollux. Parona. Palaeont. Italica I; p. 20; tav. II, fig. 1.

Dimensions:

Measurement	Value
Diameter	43 mm. = 1.00
Width of the umbilicus between the sutures	19 mm. = 0.40
Height of the last whorl above the suture	18 mm. = 0.37
Thickness of the last whorl	18 mm. = 0.37

The measurements, owing to insufficient preservation, were not made on the end of the shell, which has a diameter of 55 mm.

One specimen, for this species, is of very large size. Not having at hand the works of Reinecke and Zieten, in my interpretation of this species I rely on S. Nikitin and G. Lahusen. According to this interpretation, Cosm. Pollux includes forms possessing coarse and thick ribs and strong tubercles, the number of siphonal tubercles generally corresponding to the number of lateral ones. The variability of this species is rather considerable: the ribs and tubercles are sometimes more frequent and sometimes rarer; the whorls are sometimes higher and sometimes lower, although in general their transverse section shows only a slight predominance of height over thickness. With an increase in the number of ribs and in the height of the whorls it approaches Cosmoc. Castor Rein. sp.

Locality. Tsudakhar; Middle Callovian limestone (Bb). Its distribution is rather extensive. In the Ryazan Province it is known in the zones with Per. Mosquensis and Per. mutatus; in Swabia in the Ornate Clay—Brauner Jura ζ—the zone with Reineckia anceps; in Yaroslavl Province in beds with Quenst. Leachi; in Northern Italy in beds with Posidon. Alpina.

5. Cosmoceras aculeatum Eichw. sp.

1. Cosmoceras aculeatum. Lahusen. Ryazan Jura; p. 59; pl. VII, figs. 14–17.

There also see the synonymy, to which I can add:

1. Cosmoceras aculeatum. Teisseyre. Rjäsan; p. 577; pl. V, fig. 54.
2. Cosmoceras aculeatum. Nikitin. Yaroslavl; p. 71.

A fragment of a form possessing rather strong ribbing, well-developed siphonal and lateral tubercles, and weaker umbilical tubercles. From the lateral tubercles toward the siphonal side there usually proceed three ribs each; between these latter, additional intermediate ribs also appear; all these ribs partly disappear at the margin of the siphonal side, and partly adjoin two or three at a time to the siphonal tubercles. These latter, on my specimen, are already joined by thick ribs.

Similarities and differences. It seems to me probable that this species is identical with Amm. gemmatus Phill. (Geol. of Yorkshire; 2 ed.; p. 113; pl. VI, fig. 17) from the Kelloway’s Rock of Weymouth and Scarborough.

The specimen from Scarborough in the collection of the Tomsk Technological Institute is not distinguishable from Cosm. aculeatum. The indistinctness of Phillips’s figure, however, does not allow me to be convinced of the identity of our Yorkshire specimen with Amm. gemmatus. If the identity I propose is correct, then the name Cosm. aculeatum Eichw. sp. must be replaced by the name Cosm. gemmatum Phill. sp.

Locality: Tsudakhar; Middle Callovian limestone (Bb). Distributed in the horizon with Per. Mosquensis in Ryazan Province, in beds with Quenst. Leachi in Yaroslavl Province, at Popilany, in the Brauner Jura ζ of Swabia, and in the Callovian deposits of France and Yorkshire.

6. Cosmoceras Gulielmi Nik. (non Sow.?), 1881.

1. Ammonites Jason (pars). d’Orbigny. Terrains Jurassiques; I; p. 446; pl. 159, fig. 1—2.
2. Cosmoceras Gulielmi. Nikitin. Rybinsk; p. 94; pl. IV, fig. 31.
3. Cosmoceras Gulielmi. Nikitin. Jura von Elatma; I Th.; S. 10.
4. Cosmoceras Jason. Lahusen. Ryazan Mountain; p. 55; pl. VII, fig. 2—6.
5. Cosmoceras Gulielmi. Teisseyre. Rjäsan; S. 576; Tab. IV, Fig. 29.
6. Cosmoceras Gulielmi. Nikitin. Yaroslavl; p. 70.
7. Cosmoceras Gulielmi. Nikitin. Kostroma; p. 114.
8. Cosmoceras Gulielmi. Nikitin. Jura von Elatma; II Th.; S. 47.

A specimen 68 mm in diameter. Rather coarse ribbing, well-developed tubercles of all three rows, the numerous siphonal tubercles, and the ribbing of the siphonal side that appears with age are features shared with Cosm. Gulielmi of S. Nikitin.

Similarities and differences: As regards the identity of this species with Amm. Gulielmi Sow. (Min. Conch.; IV; p. 5; pl. 311), I am rather inclined to a negative opinion. Sowerby’s illustration shows a form with much finer ribbing. Amm. Jason Rein. is still more finely ribbed.

Not having Zieten’s work at hand, I cannot say how Amm. Gulielmi in his treatment relates to the form under consideration. Judging by

to Quenstedt’s illustration (Ammon. Schwäb. Jura, Tab. 83, Fig. 4); it also has finer ribbing than Cosmoceras Gulielmi Nik. It may be that the species under consideration should receive a new name, but I do not have sufficient data for establishing it, and therefore I prefer to call it Cosm. Gulielmi Nik.

Locality: Gunib; Callovian greenish limestone (No. 1). Distributed in the horizon with Per. Mosquensis and Per. mutatus of the Ryazan Government; in the horizon with Cadoceras Milaschewici of the Yaroslavl, Tambov, and Kostroma Governments; in the Callovian deposits of France, and probably of other European countries as well.

Group Cosmoceras Proniae. Teiss.

7. Cosmoceras subornatum n. sp. (Plate I, fig. 1 a—b).

A fragment of a discoidal shell, which had a diameter of about 80 mm. Height of the last whorl above the suture 34 mm., above the preceding whorl 27 mm.; thickness of the last whorl—25 mm. The umbilicus is rather narrow. The cross-section of the whorls in the adult state is high; the siphonal side is very gently rounded and separated from the lateral sides by a well-marked, although somewhat rounded, edge. The lateral sides are convex, most of all at the boundary of the lower third. The umbilical margin is rather indistinct. The ribs are numerous; beginning at the suture, they run somewhat obliquely backward; then, at the boundary of the lower third of the height of the whorl, they form elongate swellings (lateral tubercles) and turn in a radial direction; beyond these swellings the ribs become smoothed out and indistinct (on the nucleus), and then divide into 2–3 branches; these branches are rather sharp and continue without interruption across the siphonal side, forming along its margins only barely perceptible indications of siphonal tubercles; the young whorls are very similar to Cosm. ornatum Schl. sp. The suture line is preserved rather crudely and does not present any essential peculiarities.

Similarities and differences. The species is very close to Cosm. ornatum Schl. sp. For the young, though poorly preserved, whorls I cannot indicate any distinguishing characters. The larger whorls, however, differ in a higher cross-section, a narrower umbilicus, finer ribbing, a broad, barely rounded, ribbed siphonal side, the almost complete disappearance of the siphonal tubercles, and the absence of any indications of a siphonal groove.

Cosm. ornatum of corresponding dimensions was described and figured by S. Nikitin (Rybinsk; p. 97; Pl. IV, fig. 34). Although in his text the disappearance of the siphonal tubercles and of the siphonal groove is also noted, the figure, by its dimensions corresponding to my specimen, shows precisely the opposite characters. Therefore my species acquires the characters of the adult state earlier than Cosm. ornatum. My species shows still greater similarity to Cosm. enodatum Lah. (non. Nik.) (Ryazan Jurassic, p. 55; Pl. VI, fig. 9); but my specimen is much larger, and its preceding whorl already resembles Cosm. ornatum completely, while for Lahusen’s form the ornate stage is apparently unknown; if such a stage also exists in Cosm. enodatum Lah., then it must evidently end much earlier than in my form. Some figures of Amm. ornatus in Quenstedt (Die Ammon. Schwäb. Jura; Tab. 83, Fig. 25 and Tab. 84, Fig. 13) show similarity to my form, but the siphonal tubercles (perhaps owing to preservation of the shell itself?) are expressed much better in the Swabian ammonites.

Locality: Gubden; yellowish-green limestone (No. 1). It is probable that this form is also distributed in other countries, but is confused with Cosm. ornatum.

8. Cosmoceras Žudacharicum n. sp. (Pl. I, fig. 2 a–b).

A fragment of a discoidal shell with a rather narrow umbilicus. The whorls are high; the siphonal side is almost flat, the lateral sides weakly convex; the umbilical margin is rounded, but rather distinct. The ribs, more widely spaced than in the preceding form, at first from the suture likewise run somewhat obliquely backward, but already at the umbilical margin become radial, forming here weak elongated swellings (umbilical tubercles). Then the ribs lower and again swell at the boundary of the lower third of the whorl height, forming here distinct, although likewise elongated, lateral tubercles. From the latter, farther along the sides, depart three finer ribs. Between the groups of these ribs there are also intercalated intermediate ribs of the same character. All these ribs, on approaching the margin of the siphonal side, usually unite in threes in siphonal tubercles. From these latter one rib departs from each; these ribs, crossing the siphonal side, unite without interruption with the opposite siphonal tubercles.

The lobate line has been preserved coarsely and presents no interesting peculiarities.

Similarities and differences. The joining of the ribs on the siphonal tubercles recalls Cosm. Duncani Sow. sp. (Min. Conch.; II; p. 129; pl. 157); the same kind of joining is found, as a sporadic phenomenon, in Cosm. Proniae Teiss. (Rjäsan; S. 557; Taf. III, Fig. 15—18). From both of these species my form differs in its flat, broad siphonal side, crossed by strong ribs without any hint of a siphonal furrow, and in the fact that the ribs usually join on the siphonal tubercles in threes. From Cosm. transitionis Nik. (Rybinsk; p. 98; pl. IV, fig. 35), my form differs in the character of the siphonal side and in the entirely different type of ribbing on the lateral sides.

Locality. Tsudakhar; middle Kelloway marly limestone (Bb).

Group Cosmoceras Gowerianum Sow. sp.

9. Cosmoceras Daghestanicum n. sp. (Pl. I; figs. 3 a—b).

A fragment of a flat form with a rather narrow whorl, measuring about 70—80 mm in diameter. The height of the last whorl above the suture is 30 mm.; its thickness is 17 mm. The siphonal side is flat; the lateral sides are slightly convex. The umbilical margin is indicated only by umbilical tubercles. The ribs, beginning at the suture, run obliquely backward, then form distinct, though elongate, umbilical tubercles, then turn radially and become very weak (on the nucleus). At the boundary of the lower third of the whorl height the ribs form well-expressed lateral tubercles; from the latter there depart 3—4 very fine ribs, between groups of which there appear another 3—4 intercalated ribs. All these ribs, slightly thickening, go toward the siphonal side. At the edge of the latter these ribs are already rather thick, are occasionally even joined again in pairs, and then, without forming distinct tubercles, cross the siphonal side regularly. The lobate line is not visible.

Similarities and differences. From the closely related forms Cosm. subnodatum Teiss. (Rjäsan; S. 549; Taf. II., Fig. 9—11), Cosm. Jason Rein. sp. (Lagusen. Ryazan. Jura; pl. VII, fig. 7—under the name Cosm. Gulielmi), Cosm. Proniae Teiss. (Rjäsan; S. 557; Taf. III, Fig. 15—18), my form differs in its broad, ribbed siphonal side. From representatives of the genus Kepplerites it differs in its well-developed lateral and umbilical tubercles. This form, like the two preceding ones, repre—

has one of the types of the genus Cosmoceras, acquiring a broad, flat, ribbed siphonal side—one of the characters of the Runcinate stage of the genus Kepplerites Neum.

Locality. Tsudakhar; Middle Callovian marlstone limestone (Bb).

10. Cosmoceras macrocephali n. sp. (Pl. I; fig. 4 a—b).

Dimensions.

	mm.
Diameter	27 = 1.00
Width of umbilicus	11 = 0.41
Height of the last whorl above the suture	11 = 0.41
Height of the last whorl above the preceding whorl	9 = 0.33
Thickness of the last whorl	7 = 0.26

A small specimen of discoid form, with an umbilicus of moderate width. The whorls are high and narrow; the siphonal side bears a smooth groove; the lateral sides are gently rounded; the umbilical margin is rounded, but quite distinct. The ribs begin already on the umbilical surface, at a short distance from the suture, and here run somewhat obliquely backward. Beginning at the umbilical margin the ribs run almost radially, forming only here and there faint indications of umbilical and lateral tubercles.

At the boundary of the lower third of the height of the whorl the ribs begin to branch; here they divide into 2—3 branches, and between the groups of these branches there appear 1—2 intermediate ribs. All these ribs run slightly falciformly and end in small tubercles at the margin of the siphonal groove. The regularity of the sculpture is interrupted in places by the fact that the branches do not depart at the same height. In one place the branches of the main ribs are especially strongly bent backward, as a result of which there is a rather noticeable irregularity in the ribbing; these curved branches (5 in number) are at the same time somewhat stronger than the neighboring ribs. The lobate line is of the type of Cosm. Jason.

Similarities and differences. In its sculpture this species is very close to Cosm. enodatum Lah. (non Nik.) (Ryazan Jurassic; p. 55; pl. VI, fig. 9), but differs in its much higher whorls and narrow siphonal side. These latter characters bring it close to Cosm. Jason Rein. sp. (Lahusen. Ryaz. Jura; p. 57; pl. VII,

fig. 7—under the names Cosm. Gubielmi and Cosm. subnodatum Teiss. (Rjäsan; p. 549; Tab. II, Fig. 9—11); but from these two forms it is clearly distinguished by the absence of distinct lateral and umbilical tubercles.

Locality: Tsudakhar; Callovian limestone (Ac.).

Morphoceratida.

Fam. Reineckidae.

Genus Oecoptychius. Neumayr. 1878.

11. Oecoptychius aff. refractus Rein. sp. 1818.

1. Ammonites refractus. d’Orbigny. Terr. Jurass. I; p. 473; pl. 172, fig. 3—7.

2. Ammonites refractus. Quenstedt. Cephalopoden; S. 150; Tab. XI, Fig. 12.

3. Ammonites refractus. d’Orbigny. Prodrome I; p. 331.

1856—58. Ammonites refractus. Oppel. Die Juraformation; S. 561.

1. Ammonites refractus. Quenstedt. Der Jura; S. 524; Taf. 69, Fig. 25—30.

2. Ammonites refractus. Quenstedt. Die Ammon. des Schw. Jura; S. 762; Tab. 86, Fig. 37—51 and Ammonites refractus macrocephali S. 766; Tab. 86, Fig. 51—52.

3. Oecoptychius refractus and Oecoptychius refractus macrocephali. Pompecki. Uber Ammonit. mit anomal. Wohnkamm.; S. S. 247—249; Taf. IV, Fig. 4—5.

A fragment, which in sculpture and in the transverse section of the whorls is identical with Oec. refractus, but differs from the latter in the blunter (nearly rectangular) geniculate bend of the body chamber. In this respect it stands closer to Oec. refractus macrocephali, but the bend of the body chamber in the Caucasian form is still blunter.

Locality: Tsudakhar; Middle Callovian marly limestone (Bb). Oecoptychius refractus is distributed in the Brauner Jura ζ of Swabia and in the Callovian deposits of France; Oecoptychius

refractus macrocephali characterizes the macrocephalus zone (lower Callovian, Brauner Jura ε) of Swabia.

Genus Parkinsonia. Bayle. 1878.

12. Parkinsonia Parkinsoni Sow. sp. 1823.

1. Ammonites Parkinsoni. Sowerby. Miner. Conch. II; p. 1; pl. 307.

2. Ammonites Parkinsoni. d’Orbigny. Terr. Jurass. I; p. 374, pl. 122.

3. Ammonites Parkinsoni depressus. Quenstedt. Cephalopoden: S. 144; Taf. II, Fig. 5. et Amm. Parkinsoni planulatus; S. 143; Tab. 11, Fig. 2.

1856—58. Ammonites Parkinsoni. Oppel. Die Juraformation; S. 379.

1. Ammonites Parkinsoni depressus. Quenstedt. Der. Jura; S. 472; Taf. 63, Fig. 9.

2. Ammonites Parkinsoni. Quenstedt. Die Ammoniten des Schwäbischen Jura II; S. S. 600—605; Tab. 71, Fig. 22; Tab. 72, Fig. 4,6; et Ammonites Parkinsoni planulatus; S. S. 598—599; Tab. 71, Fig. 16, 19—21.

3. Parkinsonia Parkinsoni. Schlippe. Die Fauna des Bathonien im Oberrhein. Tieflande; S. 207; Taf. IV, Fig. 1, 3, 5.

4. Parkinsonia Parkinsoni. Neumayr u. Uhlig. Jurafossilien des Kauk.; S. 53.

5. Parkinsonia Parkinsoni. Papp. in M. O. Déchy’s “Kaukasus”; B. III; S. 144.

A fragment of this species was found by me in a marly concretion at the foot of Mount Guniob, and is an accidental and the only representative of the Middle Jurassic fauna in my material. In the Caucasus it is very widespread; in Dagestan it is cited (Neumayr, Renz, Papp) from the shale sequence, usually in concretions. In Europe it characterizes the upper zone of the Bajocian stage in Swabia, France, England, etc.

Dactyliotida,

Family Aspidoceratidae.

Genus Aspidoceras. Zittel. 1866.

13. Aspidoceras diversiforme Waag. 1875.

1. Aspidoceras diversiforme. Waagen. Cutchcephalopoden; p. 90; pl. XVII, fig. 1.
2. Aspidoceras diversiforme. Nikitin. Jura von Elatma; I Th.; S. 109; Taf. II, Fig. 9—11.
3. Aspidoceras diversiforme. Lagusen. Ryazan Jurassic; p. 71.
4. Aspidoceras diversiforme. Teisseyre. Rjäsan; S. 599.
5. Aspidoceras diversiforme. Nikitin. Jura von Elatma; II Th.; S. 47.

I refer to this species three fragments; two of them represent young whorls, and one fragment belongs to an individual that had more than 180 mm in diameter (consisting almost entirely of air chambers). The young whorls bear on the flanks strong straight ribs, dividing outward into 2–4 branches, interrupted on the siphonal side (on the cast) by a smooth band. On the adult whorls only the main ribs are preserved, and the siphonal side becomes smooth. The ribs on the adult whorls swell at the ends into sharply individualized tubercles, of which the umbilical one is more strongly developed. The suture line differs from that figured by Waagen by one additional auxiliary lobe and by broader saddles. In this respect it more closely approaches the figure of S. Nikitin. It is difficult to explain the significance of this difference, in view of the generally rather poor preservation of the suture lines on my Caucasian specimens.

Similarities and differences. This species occupies a rather isolated position. The suture line, judging from the drawings, differs sharply in the Russian and Indian specimens; Teisseyre, speaking of his Ryazan specimens, considers their suture line similar to Waagen’s figure, and not to Nikitin’s. The suture line of the Caucasian specimen occupies rather an intermediate position between the Russian and the Indian. It is possible that the Russian and Indian forms may be separated as different species; but, not having ma—

lost material for separating them, I must unite the Caucasian form with them and understand this species in a comparatively broad sense.

Occurrence. Tsudakhar; Middle Callovian marlstone-limestone (Bb). Distributed in the upper Callovian (Athleta-bed) of India and in the middle Callovian (horizon with Cad. Milaschevici—Tambov Gov.; horizon with Per. mutatus—Ryazan Gov.) of Russia.

Genus Peltoceras. Waagen. 1871.

14. Peltoceras athleta. Phil. sp. 1829.

1. Ammonites athleta. Phillips. Geology of Yorkshire; 2 ed.; p. 113; pl. 6, fig. 19.

2. Ammonites athleta. d’Orbigny. Terr. Jurass. I; p. 457; pl. 163—164.

3. Ammonites athleta. Quenstedt. Cephalopoden; S. 189; Tab. 16, Fig. 1—2.

4. Ammonites athleta. d’Orbigny. Prodrome I; p. 329.

1856.—58. Ammonites athleta. Oppel. Die Juraformation; S. 588.

1. Ammonites athleta. Quenstedt. Der Jura; S. 538; Tab. 71, Fig. 1—3.

2. Peltoceras athleta. Waagen. Cutchcephalopoden; p. 81; pl. XVII, fig. 2—3.

3. Peltoceras athleta. Lahusen. Ryazan Mountain; p. 69; pl. X, fig. 9.

4. Peltoceras athleta. Teisseyre. Rjäsan; S. 601.

5. Peltoceras athleta. Neumayr und Uhlig. Jura foss. des Kauk.; S. 66.

6. Peltoceras athleta. Papp in Déchy’s “Kaukasus”; B. III; S. 146.

7. Peltoceras athleta. Semenov. Mangyshlak; p. 108.

A fragment of a rather large specimen (height of the last whorl above the suture 25 mm, thickness—35 mm). The flat siphonal side, two rows of tubercles on each side, with the siphonal tubercles stronger than the umbilical ones, flat, divided by longitudinal furrows into two, the ribs of the siphonal side identical with those of Pelt. athleta. However, the Caucasian specimen has lower and thicker whorls than all the cited figures. Since the latter in this ...

also show so little similarity to one another, then until the species is separated I must describe the Caucasian form as Pelt. athleta.

Occurrence: Gunib; Kelloway greenish limestone (No. 1). Widely distributed in Europe, as a guiding form of the Upper Kelloway (England, France, Germany, etc.). In Ryazan Province it is known from the horizon with Card. Lamberti. In the Caucasus it is cited from the conglomerate-like tuff of Kabaktan and from the gray sandy calcareous marl at the foot of Mount Gunib. It is also known from the Upper Kelloway of India and the Transcaspian region.

15. Peltoceras Chauvinianum d’Orb. sp. 1846.

1. Ammonites Chauvinianus. d’Orbigny. Terr. Jurass.; p. 460; pl. 165.

2. Ammonites Chauvinianus. Leckenby. Qu. J. Geol. Soc. Vol. XV; p. 9.

3. Peltoceras Chauvinii. Siemiradsky. Z. d. D. G. G. Bd. XLIV; S. 419.

4. Ammonites Chauvinianus. Papp. Déchy’s “Kaukasus”; Bd. III; S. 146.

I refer to this species a fragment with a flatly rounded siphonal side and ribs forming tubercles only at the boundary of the siphonal side and there immediately bifurcating.

Similarities and differences. It is quite probable that Ammonites athleta unispinosus Quenst. also belongs, at least in part, to this same species (Ammon. Schwäb. Jur. II.; S. 794.; Taf. 89, Fig. 5, 11—15). However, none of his figures has complete similarity with d’Orbigny’s illustration and with my specimen, although the differences may not be so great as to warrant separating Quenstedt’s form from Pelt. Chauvinianum.

Occurrence: Tsudakhar; Middle Kelloway marly limestone (Bb). It is also known from the gray sandy calcareous marl at the foot of Mount Gunib and from the Kelloway deposits of Poland, France, England, and, apparently, from the Brauner Jura ζ of Swabia (d’Orbigny, Leckenby, Siemiradzki).

16. Peltoceras annulosum Qu. sp. 1887.

1886—87. Ammonites annulosus. Quenstedt. Die Ammon. des Schw. Jura II; S. 784; Tab. 88, Fig. 22.

A fragment which appears to be identical with Quenstedt’s figure. On the siphonal side (on the nucleus) a smooth band is visible. The branches of the ribs are somewhat bent backward, and the point of branching is situated very high.

Locality: Gunib; Callovian greenish limestone (No. 1). In addition, known from the Brauner Jura ζ of Swabia. (Quenstedt).

Family Perisphinctidae.

Genus Ataxioceras. Fontannes.

17. Ataxioceras Abichi Neum. sp. 1892.

1. Perisphinctes Abichi. Neumayr und Uhlig. Jurafoss. d. Kauk. S. 66; Taf. II, Fig. 1; Taf. III, Fig. 1.
2. Perisphinctes (Ataxioceras) Abichi. Siemiradski. Monographie d. Perisphinctes; S. 226.
3. Perisphinctes Abichi. Papp in Déchy’s “Kaukasus”. B. III; S. 146.

To this species I refer 2 fragments categorically and 3 provisionally, in view of the poor preservation of the latter. The ribs, swollen at the umbilical margin and branching bidichotomously, are its characteristic features, along with the characteristic constrictions.

Locality. Tsudakhar; Middle Callovian marly limestone (Bb). It is also cited from the limestone with ammonites and belemnites of Korodag and Gunib, and from the gray sandy calcareous marl at the foot of Mount Gunib. Uhlig regards it as a Kimmeridgian form; Papp assigns the rock in which it was found to the Callovian. I consider it a Callovian form.

Genus Perisphinctes. Waagen. 1860.

18. Perisphinctes? (Procerites?) sp. ind.

A large specimen about 150 mm in diameter, compressed and in general poorly preserved. The whorls increase slowly. The young whor—

the whorls bear rather thin bipartite ribs. At 40 mm in cross-section their ribbing closely resembles the young whorls of Asp. diversiforme Waag.; at larger sizes the ribs become thick and noticeably thicken outward. At a cross-section of about 90 mm the ribs still bifurcate, and the siphonal side is ribbed. At an even larger cross-section only the flanks of the shell are covered with rows of thick ribs, and the siphonal side is almost smooth.

The lobate line has been preserved only in a rough form. The external saddle is rather broad; the 1st lateral lobe is longer than all the others; the 2nd lateral lobe is twice as short and not oblique; the sutural lobe is weakly expressed, and only two small auxiliary lobes enter into its composition.

Similarities and differences. It somewhat resembles Amm. Bakeriae d’Orb. (Terr. Jurass.; pl. 149, fig. 2—non ceterae) and Per. cobra Waag. (Cutch; Cephalopoden; p. 114; pl. XLV, fig. 1), differing from both by the thicker and less frequent ribs on the adult whorls and by the thickening of the ribs outward on whorls of medium size. The weak development of the sutural lobe and the resemblance of the young whorls to the young whorls of Aspidoceras diversiforme make one doubt even the correctness of the generic determination of this form.

Locality: Tsudakhar; Middle Kelloway marl limestone (Bb).

19. Perisphinctes (Procerites) aberrans. Waag. 1875.

1. Perisphinctes aberrans. Waagen. Cutch; Cephalopoda; p. 175; pl. XLI, fig. 1—2 (erroneously called Per. spirorbis on the plate).

2. Perisphinctes (Procerites) aberrans. Siemiradsky. Monographie der Perisphinctes; S. 305.

A large evolute form with slowly growing whorls, represented in my collection by a single specimen; the cross-section of the whorls is oval, becoming almost round where the ribs pass. The young whorls bear rather numerous 2–3-partite ribs. With age, intercalated ribs begin to predominate. At a diameter of about 40 mm the ribs become thicker and rarer; then the main ribs swell, becoming very high, and, becoming blunt, cease to bifurcate. On the adult whorls (at a cross-section of about 150 mm) the siphonal side (on the internal mold) beco—

appears smooth, and the main ribs on the flanks resemble elongated tubercles with a cutting edge.

The lobate line has been preserved in a rather rough form. The siphonal lobe is somewhat asymmetrical; the 1st lateral is longer and narrower than the siphonal; the 2nd lateral is small, but not oblique; the sutural consists of 3 auxiliary lobes, of which the 2nd is the largest; the sutural lobe is well expressed and deeper than the 1st lateral. The saddles are rather broad.

Affinity and differences. Siemiradzki has already pointed out an error in the explanation to Waagen’s plate, where Per. aberrans is named as Per. spirorbis. However, Noetling (Jurass. fauna of Baluchistan; p. I; p. 21; pl. XII, fig. 5) again repeats Waagen’s oversight and describes Per. spirorbis Waag. under the name Per. aberrans. The Caucasian specimen possesses sculpture and a cross-section of the whorls identical with Waagen’s species, but its sutural line differs from that figured by Waagen in the greater breadth of the saddles.

Here the same relationship is repeated as exists between the Russian (in S. Nikitin) and Indian forms of Aspidoceras diversiforme. In uniting there the Caucasian form with the Indian, I prefer to do the same here as well, since under these conditions there will be greater consistency in the list.

Locality. Tsudakhar; Middle Callovian marly limestone (Bb). Distributed in India presumably in the Upper Callovian (Athleta bed) and in Poland in the Middle Callovian (Waagen, Siemiradzki).

20. Perisphinctes (Procerites) Indicus. Siem. 1899.

1. Perisphinctes spirorbis. Waagen. Cutch Cephalopoda; p. 154 pl. XLI, fig. 1—2 (on the plate erroneously named Per. aberrans).

1886—87. Ammonites cf. triplicatus. Quenstedt. Die Ammoniten des Schwäb. Jura; Tab. 80, Fig. 6.

1. Perisphinctes indicus. Siemiradzki. Monographie der Perisphinctes; S. 323; Taf. XXIII, Fig. 33.

2. Perisphinctes aberrans. Noetling. Jurassic Fauna of Baluchistan; p. I; p. 21; pl. XIII, fig. 5.

One somewhat compressed specimen with high whorls, somewhat narrowed toward the siphonal side, on the body chamber and

near it and with an almost elliptical cross-section of the younger whorls. The ribbing on the younger whorls is rather fine, and the ribs are bipartite; later the principal ribs swell, and intermediate ribs appear. The disappearance of ribbing is not yet observed on my specimen, which has a diameter of only about 85 mm.

The lobate line has the 1st lateral lobe longer than the siphonal one; the 2nd lateral lobe is small and, together with two auxiliary ones, forms part of a very deep sutural lobe.

Similarities and differences: From Per. Zurecznyi. Siem. (l. c. S. 325; Fig. in Text 82; Taf. XXII, Fig. 25—26; Taf. XXVI, Fig. 51), to which it is very similar, it differs in its less dense ribbing.

Locality: Found washed out in a ravine along the road from Khodjal—Makhi to Tsudakhar. Distributed in East India (presumably in the macrocephalus zone), in the Kelloway of Balochistan, in the Middle Kelloway of Poland, and in the Brauner Jura ε of Swabia (Waagen, Noetling, Siemiradzky, Quenstedt).

21. Perisphinctes calvus. Sow. sp.

1. Perisphinctes calvus. Waagen. Cutch-Cephalopoden; p. 116; pl. LVI, fig. 1.

2. Perisphinctes calvus. Siemiradzki. Monographie d. Perisphinctes; S. 292; Fig. in Text 66.

To this species I assign three fragments, very similar to the cited illustration in Waagen.

Locality: Tsudakhar; Middle Kelloway marl limestone (Bb). Known from the Middle Kelloway of India, Poland, Swabia, and possibly from Popilany (Siemiradzki).

22. Perisphinctes (Grossouvria) cf. poculum Leck. sp. 1859.

1. Ammonites poculum. Leckenby. Quart. Journ. Geol. Soc. Vol. XV; p. 9; pl. I, fig. 4.

2. Perisphinctes (Grossouvria poculum). Siemiradzki. Monographie d. Perisphinctes; S. 139; Fig. in Text 16.

A fragment of a compressed nucleus, similar in general appearance and in the character of the ribbing to Leckenby’s form.

Occurrence: Tsudakhar; Middle Callovian marly limestone (Bb). Known from the Callovian of Yorkshire and from the zone with Card. Lamberti in Swabia.

23. Perisphinctes (Grossouvria) Comptoni. Pratt sp. 1841.

1. Ammonites Comptoni. Oppel. Die Juraformation; S. 555.
2. Ammonites mutatus. Trautschold. Bul. de Mosc. 1862; II; p. 209—211; pl. VI, fig. 2.
3. Perisphinctes submutatus. Nikitin. Jura v. Elatma I Th.; S. 107; Taf. I, Fig. 4—5.
4. Perisphinctes submutatus. Lahusen. Ryazan Jura; p. 64; pl. IX, fig. 3.
5. Perisphinctes subaurigerus. Teisseyre. Rjäsan; S. 583; Taf. V, Fig. 39; Taf. VI, Fig. 36—38.
6. Perisphinctes submutatus. Nikitin. Jura v. Elatma II Th.; S. 46; Taf. VIII, Fig. 40.
7. Perisphinctes submutatus. Nikitin. Kostroma; p. 120.
   1886—87. Ammonites convolutus auritulus. Quenstedt. Die Ammon. d. Schwäb. Jura; S. S. 696—697; Taf. 81, Fig. 30—34.
8. Perisphinctes submutatus. Semenov. Mangyshlak; p. 78; pl. III, fig. 3.
9. Perisphinctes submutatus. Siemiradzki. Monographie d. Perisphinctes; S. 135; Fig. in Text 14.

Four specimens, of which 2 are fragmentary. In all respects they agree with this species, if it is understood in Siemiradzki’s sense, except only that the parabolic sculpture is rather well developed up to 40 mm in diameter.

Similarities and differences: Siemiradzki unites under the name Per. Comptoni four species of earlier investigators: Amm. Comptoni Pratt., Per. submutatus Nik., Per. subaurigerus Teiss., and Amm. convolutus auritulus Qu. In its sculpture the Caucasian form most closely resembles Per. subaurigerus Teiss., while in the suture line it is closest to the illustration in Siemiradzki.

Occurrence: Tsudakhar; Middle Callovian marly limestone (Bb). Gunib; greenish Callovian marl No. 1. Known from Middle Callovian deposits of Russia, Poland, Swabia, France, and England.

24. Perisphinctes (Grossouvria) cf. Balinensis. Neum. 1871.

1. Perisphinctes Balinensis. Waagen. Cutch-Cephalopoda; p. 163; pl. XLV, fig. 2.

1886–87. Ammonites convolutus. Quenstedt. Die. Ammon. d. Schwäb. Jura; Tab. 32, Fig. 66.

1. Perisphinctes Balinensis. Siemiradzki. Monographie d. Perisphinctes; S. 134.

A poorly preserved specimen, not permitting an exact determination. In external appearance it appears identical with the cited figure in Quenstedt.

Locality: Tsudakhar; Middle Kelloway marly limestone (Bb). Siemiradzki regards this species as a form of the macrocephalus zone and indicates its distribution in Poland, Swabia, and East India. However, the figure by Quenstedt cited by him also belongs to Ornatenthon, i.e. to the Middle Kelloway.

25. Perisphinctes (Grossouvria) cf. variabilis. Lah. 1883.

1. Perisphinctes variabilis. Lahusen. Ryazan mora; p. 68; pl. X, fig. 4.

2. Perisphinctes pseudomosquensis. Siemiradzki. Zeitsch. d. Deutsch. Geol. Ges. B. 46; S 511; Taf. XXXIX, Fig. 4.

3. Perisphinctes eversus. ibidem; S. 512; Taf. XXXVIII, Fig. 5.

4. Perisphinctes variabilis. Siemiradzki. Monographie d. Perisphinctes; S. 116; Fig. in Text 12.

A compressed, worn specimen, in external appearance seeming to me indistinguishable from Lahusen’s figure.

Locality: Tsudakhar; Middle Kelloway marly limestone (Bb). Limestone in the zone with Card. Lamberti in the Ryazan province and with Cosm. Jason in Poland.

26. Perisphinctes (Grossouvria) Rossicus. Siem. 1899.

1. Perisphinctes mosquensis. Lahusen. Ryazan mora; p. 65; pl. IX, figs. 4–6.

1. Perisphinctes mosquensis. Teisseyre. Rjäsan; S. 592; Taf. VII, Fig. 48, 50; Taf. VIII, Fig. 47.
2. Perisphinctes Rossicus. Siemiradzki. Monographie d. Perisphinctes; S. 106.

1 specimen and fragments of two others. The well-developed parabolic sculpture distinguishes it from similar young whorls of Per. Comptoni.

Locality: Tsudakhar; Middle Callovian marly limestone (Bb). Gunib; Callovian greenish marl (No. 1). Distributed in the Middle Callovian of the Ryazan Governorate, Swabia, and France (Siemiradzki).

27. Perisphinctes (Grossouvria) subtilis. Neum. 1871.

1. Ammonites convolutus ornati. Quenstedt. Der Jura; S. 541; Taf. 71, Fig. 9.
2. Perisphinctes subtilis. Lahusen. Ryazan Jurassic; p. 67; pl. IX, fig. 12.
   1886—87. Ammonites convolutus. Quenstedt. Die Ammoniten des Schwäb. Jura; Taf. 79, Fig. 16, 22.
3. Perisphinctes subtilis. Parona. Palaeontogr. Italica I; p. 22; tav. II, fig. 3.
4. Perisphinctes subtilis. Siemiradzki. Monographie d. Perisphinctes; S. 81.

A specimen 25 mm in diameter. Fine dichotomous ribbing, constrictions, the rounded form of the cross-section of the whorls, and a simple suture line with a narrow, almost unbranched first lateral lobe compel its assignment to this species.

Similarities and differences. The cited illustrations, taken together, represent a rather variable form. My specimen among them is relatively more finely ribbed, has a comparatively high cross-section of the whorls, and its whorls increase comparatively slowly.

Locality: Gunib; it was delivered by Prof. A. Shtukenberg and was completely cleaned of the rock, so that I can say nothing about its stratigraphic position. By the character of the co-

in preservation it resembles more the layer of Ac. Tsudakhar, and I think that below typical Middle Callovian will be found. Distributed in the Callovian deposits of the upper (Lahusen), middle, and lower (Quenstedt) of Russia, Poland, Swabia, France, and the Venetian Alps.

Fam. Stepheoceratidae.

Genus Erymnoceras. Hyatt.

23. Erymnoceras Renardi. Nik. sp. 1881.

1. Stephanoceras Renardi. Nikitin. Jura v. Elatma; S. 120; Taf. II, Fig. 24.

2. Stephanoceras Renardi. Lahusen. Ryazan Jurassic; p. 54; pl. VI, fig. 2 (under the name Steph. coronatum).

3. Stephanoceras Renardi. Nikitin. Jura v. Elatma II Th; S. 49.

1886–87. Ammonites coronoides. Quenstedt. Die Ammon. d. Schwäb. Jura. S. 777; Tab. 87, Fig. 34—37.

1. Stephanoceras coronoides. Neumayr u. Uhlig. Jurafossilien d. Kaukasus; S. 50.

2. Stephanoceras coronoides. Semenov. Mangyshlak; p. 91.

Dimensions:

Measurement	Value
Diameter	90 mm. = 1.00
Width of the umbilicus between the sutures	37 mm. = 0.41
Width of the umbilicus between the tubercles	52 mm. = 0.58
Height of the last whorl above the suture	34 mm. = 0.38
Height of the last whorl above the preceding one	25 mm. = 0.28
Thickness of the last whorl	45 mm. = 0.50

Inflated form with a deep funnel-shaped umbilicus. The ribs, weakly expressed on the umbilical surface, form tubercles on the margin of the last whorl; from each of the latter two ribs extend obliquely forward, and toward the end of the last whorl intermediate ribs also appear. On the siphonal side the ribs form an arcuate forward bend.

The lobate line, as in Erymn. coronatum Brug. sp.

Similarities and differences. Close to Erymn. coronatum Brug. sp., but differs from the latter in its higher whorls and

somewhat roof-like convex siphonal side. I do not consider it possible to distinguish Er. Renardi Nik. sp. and Er. coronoides Qu. sp., given the present state of study of these forms. It is possible that subsequently it will be possible to distinguish one species, with a more roof-like siphonal side, from another, with a more regularly rounded one; but both in Swabia and in Russia there is both the one and the other form. The name given by Nikitin has priority over the name given by Quenstedt.

Locality: The single specimen was found washed out in a ravine along the road from Khodzhal-Makhi to Tsudakhar together with Perisph. Indicus. Neumayr cites it from the pyritized marl of Gunib and from a similar rock of Korodag. It is distributed in the Middle Callovian of the Ryazan and Tambov provinces, Swabia, France, and the Transcaspian Region.

Genus Macrocephalites. Sutner.

29. Macrocephalites macrocephalus Schl. sp. 1820.

1. Ammonites macrocephalus. Schlotheim. Petrefactenkunde; S. 70.

2. Ammonites macrocephalus. d’Orbigny. Terrains Jurassiques I; p. 430 (non pl. 151?).

3. Ammonites macrocephalus compressus. Quenstedt. Cephalopoden; S. 184; Tab. 15, Fig. 1.

4. Ammonites macrocephalus. Oppel. Die Juraformation; S. 547.

5. Stephanoceras macrocephalum. Gemmellaro. Sopra alc. fauna etc.; p. 23; tav. IV, fig. 1.

6. Stephanoceras macrocephalum. Waagen. Cutch-Cephalopoda; p. 109; pl. XXV; XXVII, fig. 1; XXIII, fig. 5.

7. Stephanoceras macrocephalum. Nikitin. Kostroma; p. 115.

8. Macrocephalites macrocephalus. Neumayr u. Uhlig. Jurafossilien d. Kaukasus; S. 52.

9. Macrocephalites macrocephalus. Papp in Déchy’s “Kaukasus”; B. III; S. 145.

A small specimen (about 40 mm in diameter), consisting only of air chambers. Fragments of larger whorls show that already on the next whorl inward from the core the umbilical part became smooth. The suture line is complex, of the macrocephalite type.

Similarities and differences. Taking this understanding of the species, to which Waagen adheres, I reject the illustrations that seem to me too coarsely ribbed (d’Orbigny: l. c.; pl. 151. Nikitin: Jura v. Elatma I Th.; Taf. III, Fig. 15—17; II Th.; Taf X., Fig. 46).

Locality. Tsudakhar; Callovian limestone (Ac). A universally distributed guiding form of the Lower Callovian.

Arietida.

Fam. Oppelidae.

Genus Hecticoceras. Bonarelli. 1893.

30. Hecticoceras lunula. Zieth. sp. 1830.

1. Ammonites hecticus compressus. Quenstedt. Der Jura; S. 546; Tab. 72, Fig. 8.

2. Harpoceras lunula. Waagen. Cutch-Cephalopoda; p. 63; pl. XIV, fig. 1.

3. Harpoceras lunula. Lahusen. Ryazan Jurassic; p. 72; pl. XI, figs. 1—5.

4. Harpoceras lunula. Tesseyre. Rjäsan; S. 542; Taf. I, Fig. 2.

5. Harpoceras lunula. Nikitin. Jura, v. Elatma II Th; S. 49.

6. Harpoceras lunula. Neumayr u. Uhlig. Jurafossilien d. Kaukasus; S. 44.

Two fragments; one of a young whorl, the other of an adult one, by the comparatively fine ribbing at a young age and by the narrow umbilicus, must be assigned to this species.

Similarities and differences: I do not venture to include in the synonymy of this species either the citation from Renz (“Der Jura v. Daghestan”; S. 73), or that of K. Bogdanovich (Syst. Dibrar; p. 132); the authors give neither a figure nor a description, and moreover in their works this Callovian form appears in Renz together with Parkinsonia Parkinsoni, ferruginea etc., i.e. with Bathonian and Bajocian species, and in Bogdanovich with Lioceras concavum and belemnites of Bajocian age.

Locality: Tsudakhar; Middle Callovian marly limestone (Bb). It is cited by authors chiefly from the Callovian, espe—

commonly Middle Callovian deposits of the Caucasus, Russia, Swabia, France, India.

31. Hecticoceras pseudopunctatum. Lah. sp. 1883.

1. Ammonites Brightii. d’Orbigny. Paléont. de la Russie; p. 431; pl. XXXIII, fig. 9–13.
2. Ammonites lunula (pars). d’Orbigny. Terr. Jurass. I; p. 459; pl. 157, fig. 1–2.
3. Ammonites hecticus lunula. Quenstedt. Cephalopoden; S. 118; Tab. 8, Fig. 2.
4. Ammonites punctatus. Trautschold. Ergänz. z. Fauna d. Russ. Jura; S. 91; Taf. VII, Fig. 16.
5. Harpoceras pseudopunctatum. Lahusen. Ryazan Jurassic; p. 74; pl. XI, fig. 10–13.
6. Harpoceras pseudopunctatum. Semenov. Mangyshlak; p. 90.

Four specimens in fragments are, in all essential respects, similar to the figures of Lahusen.

Similarities and differences: From Harp. lunula they differ in the tubercles on the umbilical ends of the ribs, in the lower whorls, and in the broader umbilicus. From Harp. punctatum they differ in the higher whorls and the narrow umbilicus.

Locality. Tsudakhar; Middle Callovian marly limestone (Bb). Gunib; Callovian greenish marl (No. 1). Distributed in the Callovian, especially Middle Callovian, deposits of Ryazan Province, Swabia, France, and Mangyshlak.

Loco incerto.

32. Ammonites sp.

A small specimen in very poor preservation, with a moderately broad umbilicus and rather high whorls; traces of ribbing are visible only near the umbilicus, and even there very indistinctly, in the form of flatly rounded folds.

I could determine neither the genus nor the species of this ammonite, and mention it only because, perhaps, it alone could represent a hint of Mediterranean elements in the Jurassic ammonite fauna of Dagestan (possibly Haploceras).

Locality: Gunib; Callovian greenish marl (No. 1).

GASTROPODA.

Gastropoda are represented in my material only by a small number of poorly preserved casts, which do not at all permit exact determination. Therefore, with respect to this group, I confine myself only to certain comparisons, indicating rather the possible than the actual relationships of my Dagestan specimens with forms known in the literature.

Streptoneura.

Ctenobranchiata.

Platypoda.

Taenioglossa.

Fam. Naticidae.

Genus Natica. Adanson. 1757.

33. Natica cf. globosa. Morr. and Lyc. 1854.

1. Natica globosa. Morris and Lycett. Great Oolite Mollusca; p. I; p. 43; pl. VI, fig. 14.

3 casts, which I cannot distinguish from the cited illustration. The species Natica globosa belongs to Roemer; but the illustration of the German form available to me (Quenstedt. Gasteropoden. Tab. 195, fig. 1) already appears different: its whorl is lower. Therefore I consider it possible only to point to the identity of my casts with the illustration in Morris and Lycett.

Locality: Tsudakhar; Middle Callovian marly limestone (Bb). Natica globosa is cited both from the Bathonian and from the Kimmeridgian stages; consequently, it is also possible in the Callovian. One cast of very poor preservation was supplied by Prof. Stuckenberg from Gunib; in its rock it does not differ from the Tsudakhar ones.

34. Natica? sp.

A nucleus with preserved pieces of shell. In form it is very similar to Natica Calypso d’Orb. (Terr. Jurass. II; p. 202; pl. 292, fig. 9—10), but differs from the latter in the presence of very weak spiral sculpture in the form of low spiral riblets. I am not even certain of the correctness of the generic determination.

Locality: Tsudakhar; Callovian limestone (Ac).

Aspidobranchia.

Rhipidoglossa

Family Turbinidae.

Genus Turbo. Linnée 1758.

35. Turbo? sp.

A nucleus, apparently of smooth form. It may have belonged to a species resembling Turbo Erinus d’Orb. (Terr. Jurass. II; p. 362; pl. 336, fig. 12—14) from the Corallian of France.

Locality: Tsudakhar; Middle Callovian marly limestone (Bb).

Family Pleurotomariidae.

Genus Pleurotomaria. Defrance. 1821.

36. Pleurotomaria sp.

A nucleus of low conical form with slowly increasing, numerous whorls. Since it is deformed (somewhat compressed from top to bottom), I cannot compare it with any definite form. The same result upon compression could be given, for example, by the nucleus of the Kimmeridgian Pleurotomaria Philea d’Orb. (Terr. Jurass. II; p. 576; pl. 428, fig. 1—2).

Locality: Tsudakhar; Callovian limestone (Ac.)

PELECYPODA.

Teleodesmacea.

Teleodonta.

Veneracea.

Family Veneridae.

Genus Pronoëlla Fischer. 1887.

37. Pronoëlla Calloviensis n. sp. (Pl. I; figs. 5 a–b).

Dimensions:

Length	76.	72.	51.
Thickness	50.	48.	39.
Height	72.	70.	51.

Large, thick casts with projecting umbones, occupying an almost median position. The upper margin is concave—in front of the umbones, obliquely ascending—behind them. The anterior and lower margins are rather regularly rounded and pass one into the other without a sharp boundary. The posterior margin is somewhat truncated and rather distinctly delimited from the lower one. On the surface of the casts there are traces of a convexity extending to the posteroinferior angle and delimiting the posterior field; muscular impressions and a mantle line with a weak sinus are visible.

Similarities and differences. It resembles Venus grandis Münst. (Goldfuss. Petrefacta Germaniae II; p. 245; Pl. CL, Fig. 15), but in my species the posterior margin is more truncated, the umbones are more projecting, and the lunule is smaller; the posterior field is broader and, apparently, the umbones occupy a more median position; finally, my form is somewhat longer.

Locality: Tsudakhar; middle Callovian marly limestone (Bb); Gunib; Callovian greenish marl (No. 1). A rather common form: from Tsudakhar I have remains of 6 specimens of different ages; from Gunib—2 rather poor casts.

1. Pronoëlla cf. Loweana. Morr. et Lyc. sp. 1853.

2. Cyprina Loweana. Morris and Lycett. Great Oolite Mollusca;
   p. 88; pl. XIII, fig. 2.

3. Cyprina Loweana. Semenov. Mangyshlak; p. 54.

Five nuclei, which I cannot distinguish from this Bathonian form. They differ somewhat from one another: one, in the length of the posterior part and the sharp beak, resembles fig. 2e in Morris and Lycett; another is closer to fig. 2a (l. c.); one differs from all the illustrations of Cyprina Loweana by a somewhat shorter posterior side. Thus, apart, perhaps, from a somewhat lesser thickness, the Caucasian form, as far as I can judge, differs in no way from Cypr. Loweana; since, on the other hand, such comparisons, given insufficient material, have only very slight general significance, I designate this species as cf.

Locality. Tsudakhar; Middle Callovian limestone (Bb); Cyprina Loweana is recorded from the Great Oolite of England and from the Middle Callovian of Mangyshlak.

1. Pronoëlla cf. depressiuscula. Morr. et Lyc. sp. 1853.

2. Cyprina depressiuscula. Morris and Lycett. Great Oolite
   Mollusca; p. 90; pl. XIII, fig. 4.

Nine nuclei present no tangible differences from this species. In determining them as cf. I rely on the same considerations as those expressed regarding the preceding species.

Localities: Tsudakhar; Middle Callovian limestone (Bb) (3 nuclei); Gunib; Callovian greenish marl (No. 1) (6 nuclei).

Cyclodonta.

Isocardiacea.

Fam. Isocardiidae.

Genus Isocardia. Lamark. 1799.

1. Isocardia tenera. Sow. 1821.

2. Isocardia tenera. Sowerby. Miner. Conch.; III; p. 171; pl.
   295, fig. 2.

1. Ceromya tenera. Agassiz. Myes; p. 34; pl. 8e, fig. 1—1?.

2. Isocardia tenera. d’Orbigny. Prodrome I; p. 338.

3. Isocardia Campaniensis. D’Orbigny. Prodrome I; p. 338.

4. Isocardia tenera. Morris and Lycett. Great Oolite Mollusca; II; p. 68; pl. VIII, fig. 1.

1856—1858. Isocardia tenera. Oppel. Die Juraformation; S. 566.

1856—1858. Isocardia Campaniensis. Oppel. Die Juraformation; S. 566.

1. Isocardia tenera. Morris and Lycett. Great Oolite Mollusca; Supplement; p. 57; pl. XXXVIII, fig. 5.

2. Isocardia tenera. Semenov. Mangyshlak; pp. 56 and 86.

8 internal molds, possessing the characteristic feature of the species in the form of a cordate depressed field on the anterior side; the outline is generally triangular, but in details rather variable; I have both relatively long and low and very high specimens.

Similarities and differences. Under the present conditions I do not consider it convenient to divide this form into Isocardia tenera and Isocardia Campaniensis. I do not know of a single illustration of the latter species, and d’Orbigny’s brief diagnosis does not provide sufficient material for recognizing it. As distinguishing characters of Is. Campaniensis from Is. tenera, d’Orbigny indicates: greater thickness, more strongly incurved beaks, and a blunter posterior side.

My specimens are indeed somewhat thicker than those figured by Agassiz; moreover, the greater part of them are higher, and the anterior field in them is more sharply delimited and broader.

Stratigraphically, Is. Campaniensis also fits the Caucasian shells better than Is. tenera. But, not knowing a figure of Is. Campaniensis, I am not in a position to judge the degree of its identity with the Caucasian form. Therefore I consider it more cautious not to distinguish these two species, since, in accepting the Caucasian form as a new species, I could not say in what it differs from Is. Campaniensis, while by identifying it with Is. Campaniensis I would create an artificial argument in favor of recognizing the Middle Kellovian age of the fauna to which it belongs. Is. tenera in Goldfuss (Petrefacta Germaniae II; S. 208; Tab. CXL, Fig. 7) seems too long, and its anterior field appears insufficiently sharply delimited. I consider it not superfluous to note that the Caucasian specimens are in general larger than the cited figures and in this respect resemble the Neocomian Isoc. neocomiensis Ag. (Myes; p. 35; pl. 8, fig. 11—16), but in pe-

the median field in this latter is still narrower than in the cited figures of Is. tenera; the beaks are straight, and the anterior side appears less notched, if the shell is viewed from the side. Is. corculum Eichw. (Leth. Ross. II; p. 700; pl. XXVI, fig. 3) differs, in addition to its smaller size, also in the presence of radial sculpture.

Distribution: Tsudakhar; Middle Callovian marly limestone (Bb) (2 specimens). Gunib; Callovian greenish marl (No. 1) (6 specimens). Distributed in Europe from the Bathonian stage through the Callovian inclusive. Oppel considers Is. tenera characteristic of the lower, and Is. Campaniensis of the middle Callovian. In Mangyshlak it is indicated from the middle and upper Callovian.

41. Isocardia n. sp. ind.

An incomplete internal mold of the right valve, partly with remains of the shell. The general outline, insofar as it can be determined, the projecting thick incurved umbo, and the concave (when viewed from the side) anterior and rounded lower margin recall the preceding species, but the sharply delimited anterior concave field is absent in the form under consideration. The surface is covered only with growth marks.

Similarities and differences. Very similar to the preceding species, but distinguished by the absence of a distinctly bounded anterior field. From the Portlandian Ceromya inflata Ag. (Mues; p. 33; pl. 8e, fig. 13–21), which is similar in general appearance, the Caucasian form differs in its greater height and in the absence of such regular concentric striation as is figured by Agassiz.

Locality: Tsudakhar; Callovian limestone (Ac).

Diogenodonta.

Astartacea.

Fam. Astartidae.

Genus Astarte. Sowerby. 1816.

42. Astarte undata. Gldf. sp. 1834.

1. Venus undata. Goldfuss. Petrefacta Germaniae II; S. 243; Tab. CL, Fig. 8.

1. Astarte undata. d’Orbigny. Prodrome I; p. 364.
   1856—58. Astarte undata. Oppel. Die Juraformation; S. 565.
2. Astarte undata. Quenstedt. Der Jura; S. 553; Tab. 72, Fig. 26.

An incomplete right valve, distinctly showing the characteristic sculpture and groove. Indistinguishable from the cited illustration in Quenstedt.

Locality: Gunib; supplied by Prof. Stukenberg; the rock does not differ from the Middle Callovian marly limestone from Tsudakhar (Bb). Distributed in the Middle and Upper Callovian deposits of Swabia.

43. Astarte aff. rotunda. d’Orb. 1850.

1. Astarte orbicularis. Sowerby. Mineral Conchology VI; p. 35; pl. 520, fig. 2.
2. Astarte rotunda. d’Orbigny. Prodrome I; p. 307.
3. Astarte rotunda. Morris and Lycett. Great Oolite Mollusca II; p. 84; pl. IX, fig. 12.

An incomplete specimen of a right valve. In outline it is very similar to Astarte rotunda, but is somewhat thicker, the antero-dorsal margin is somewhat more concave, and the shell itself, insofar as can be judged from the fragment present, was somewhat higher. Moreover, their age is different: Ast. rotunda is a Bathonian form, whereas the form under consideration was found in a rock that I regard as Callovian.

Locality: Tsudakhar; Callovian limestone (Ac).

Anomalodesmacea.

Anatinacea.

Fam. Pholadomyacidae.

Genus Arcomya. Agassiz. 1842.

This genus was characterized by Agassiz chiefly only by those features that can be observed on the internal mold. Terquem, having studied the hinge of certain species, found that it is identical

with the replacement by Homomya Agassiz. As a result, in Zittel’s well-known textbook the genus Arcomya is absent and remains only as a synonym, partly of Homomya, partly of Quenstedtia Morris et Lycett. (Zittel; textbook of Palaeontology; p. 389. Handbuch der Palaeontologie; R. II; S. S. 116, 124). Fischer (Manuel de Conchyliologie; p. 1166) and, following him, Choffat (Faune Jurassique du Portugal; Lamellibranches; p. 34) retain this genus, and Fischer even makes it the type of a separate family. My Caucasian material consists of internal molds alone and therefore cannot serve for a critique of these disagreements. The internal molds of Arcomya, in any case, possess a characteristic and recognizable habitus and, if one regards, as Zittel does, the genus Homomya simply as smooth Pholadomya, then Arcomya will already differ sharply from it in external appearance. An elongate, relatively flat shell (in comparison with Pholadomya), a delimited posterior field (the cardinal field of Agassiz), and the presence of a shield field delimited by two folds almost parallel to the commissural margin, make this genus essentially distinct. The genus Quenstedtia in its general outline is more similar to Arcomya, but nevertheless, in the typical species Quenstedtia oblita, the characteristic features of Arcomya are absent, and its outline is also different. Therefore I consider it more reasonable to preserve the genus Arcomya in Agassiz’s sense (Myes; p. p. 165—166); otherwise, a whole series of species described from internal molds would have to enter, without any serious grounds, into the genera Homomya and Quenstedtia, the types of which differ sharply from them.

44. Arcomya Caucasica n. sp. (Plate II; fig. 6).

Dimensions:

Length	90 mm.
Height	38 mm.
Thickness	33 mm.

The internal mold is rather large, of a strongly elongated form, with beaks situated near the anterior quarter of the shell’s length. The anterior side is somewhat damaged, for which reason its outline is not clear. The upper margin behind the beaks at first runs straight, and then gradually bends and, by a rounded angle, passes into the rounded posterior margin; the lower margin is gently rounded. From the beaks to the posteroinferior angle of the shell runs a rounded keel, delimiting a broad concave posterior field. Two distinct folds run almost parallel

to the ligamentary margin, delimiting a rather narrow escutcheon; the curvature of these folds is very slight, and they reach the margin of the shell near the middle of the length of its posterodorsal margin. The gape of the valves is rather narrow, but long. On the surface only faint traces of growth marks are noticeable.

Similarities and differences. In the position of the umbones, in size, and in thickness it recalls the Bajocian Arc. Clapensis Terqu. et Jourd. (Moselle; p. 79; pl. VI, fig. 1—4), but the Caucasian form is longer, its posterior gape is narrower, the posterior margin more rounded, the escutcheon narrower, and the folds delimiting it straighter. In the form of the escutcheon and in the outline of the posterior margin the Caucasian form resembles the Bajocian Arc. spatulata Terqu. et Jourd. (l. c. p. 78; pl. VI, fig. 5—6), but Arc. Caucasica is much thicker, somewhat longer, and its posterior field is expressed much more distinctly, the gape is narrower, and the anterior side is shorter. The Oxfordian Arc. Castroi Choffat (Faune Jurassique du Portugal; p. 36; pl. I, fig. 4—5) also recalls the Caucasian form, but Arc. Caucasica does not have such an expanded posterior part, is not so compressed from the sides anteriorly, and has umbones situated farther forward than the Portuguese species. It may be that my form represents a Callovian mutation of Arcomya spatulata.

Occurrence. Tsudakhar; Middle Callovian marly limestone (Bb).

45. Arcomya inaequivalvis n. sp. (Plate II; fig. 7 a—b).

Dimensions:

Measurement	Value
Length	63 mm.
Height	32 mm.
Thickness	18 mm.

A rather flat, elongated form with umbones situated near the boundary of the anterior third of the shell length. The upper margin in front of the umbones is obliquely ascending; behind them it is weakly concave; the posterior margin is obliquely truncated; the lower margin is flatly rounded; the anterior margin is rounded. A weak, rounded ridge delimits a concave, narrow posterior field; the escutcheon is delimited by projecting folds, and on the right valve this field is considerably broader than on the left. On the surface of the internal mold only traces of growth marks are visible.

Similarities and differences. In outline it recalls Arc. cornuta Terqu. et Jourd. (Moselle; p. 78; pl. VII; fig. 1–3), but the Caucasian form is thicker and longer, and the posterior field, insofar as one may judge from the figure, is more distinct in it. The unequal-valved character, like that observed in my form, also exists in Arc. cornuta, and also, judging from the figure, in the Oxfordian Arc. Cortazari Choffat (l. c.; p. 37; pl. I, fig. 7). The latter, however, has a much broader posterior field. The form of this field is very characteristic in the Caucasian species and recalls what is observed in the genus Thracia.

Locality. Tsudakhar; Middle Callovian limestone (Bb).

46. Arcomya cf. inflata. Terqu. et Jourd. (Plate II; fig. 9).

1871—73. Arcomya inflata. Terquem et Jourdy Monographie de l’étage Bathonien de la Moselle; p. 79; pl. VI, fig. 7—8.

Two poorly preserved internal molds, in outline and thickness, correspond rather well to this species. They also have indistinctly delimited posterior and escutcheon fields. The gape in the Caucasian specimens is, apparently, broader, as far as can be judged from the character of the posterior margin of the single valve figured by Terquem et Jourdy. Taking into account the poor preservation of my internal molds and the small probability of identity between the Bajocian and Callovian forms, I do not venture to identify them categorically.

Locality. Tsudakhar; Middle Callovian marly limestone (Bb). Arc. inflata is described from the zone with Parkinsonia Parkinsoni of France.

47. Arcomya dubia n. sp. (Plate II; fig. 8).

Dimensions:

Measurement	Value
Length	59 mm.
Height	30 mm.
Thickness	17 mm.

The internal mold is of a flat, elongated form, with umbones situated somewhat behind the boundary of the anterior third of the shell. The anterior and pos—

the edge is fairly regularly rounded, the upper and lower almost parallel. The posterior part is somewhat expanded backward. The gape is narrow in the middle and behind. The posterior area is rather broad, but not sharply delimited. The escutcheon area is weakly expressed, and only in its very anterior part. On the surface of the internal mold there are indistinct traces of rather coarse concentric sculpture.

Similarities and differences. I assign this form to the genus Arcomya with great hesitation. It recalls rather closely Arc. aequalis Terqu. et Jourd., in which the generic characters are also very unclear. The broader anterior part and, resulting from this, the horizontal position of the anterior part of the upper margin constitute the only distinct difference. The illustration of Arc. aequalis also shows, apparently (Terqu. et Jourd. Moselle; p. 77; pl. VI, fig. 9—10), a depression near the middle of the lower margin. In my form there is only a barely perceptible indication of such a depression. Moreover, Arc. aequalis is a Bajocian form. If Agassiz’s classification could be firmly maintained, I would rather refer this species to Platymya.

Occurrence. Tsudakhar; Middle Jurassic limestones (Bb).

Genus Goniomya. Agassiz. 1841.

48. Goniomya sulcata. Ag. 1842.

1. Goniomya sulcata. Agassiz. Myes; p. 7; pl. 1, fig. 8—9; pl. I b, fig. 9—12; pl. I c, fig. 13—14.
2. Goniomya constricta (pars?) D’Orbigny. Prodrome I; p. 359.
3. Goniomya sulcata. Loriol. Mollusques et Brachiopodes de l’oxfordien du Jura Bernois; p. 74.

One internal mold of the left valve and a fragment of the posterior part of the internal mold of both valves. The cylindrical form, the depression running from the umbones to the lower margin, and the character of the ribbing do not differ in any way from Agassiz’s species. The posterior part in my specimens appears to be somewhat longer, but in view of the variability in this respect in Agassiz’s figures, I see no sufficient grounds for separating the Caucasian form as a distinct species. Near the beak, in my specimen, the usual connection in Goniomya of the posterior and anterior ribs by horizontal riblets is noticeable. Agassiz neither figures nor mentions this character in the text, but since the degree of its visibility is closely associated—

is connected with the conditions of preservation, this difference cannot serve as a basis for separation.

Locality. Tsudakhar; Middle Callovian marly limestone (Bb). Gon. sulcata is an Oxfordian species and is distributed in France and Switzerland.

49. Goniomya quinquescripta. Sow. sp. 1821.

1. Mya V—scripta. Sowerby. Miner. Conch. III; p. 46; pl. 224, fig. 3—5.
2. Goniomya V—scripta. Agassiz. Myes; p. 20; pl. I b, fig. 17—19.
3. Goniomya V—scripta. Lahusen. Ryazan Jurassic; p. 34; pl. II, p. 31.
4. Goniomya V—scripta. Semenov. Mangyshlak; p. 49.

A poorly preserved incomplete cast. In the oblique position of the lines connecting the angles between the anterior and posterior ribs, and in the character of the ribbing, it is indistinguishable from the figures of Sowerby and Agassiz.

Locality. Tsudakhar; Middle Callovian marly limestone (Bb). A species widely distributed in the Callovian deposits of Europe. Semenov also cites it from the Trans-Caspian region.

Genus Pholadomya. Sow.

50. Pholadomya exaltata Ag. 1842. (Pl. II; fig. 10).

1834—1840. Pholadomya Murchisoni (pars). Goldfuss. Petrefacta Germaniae II; S. 265, Tab. 155, Fig. 2 a—b.
1837. Pholadomya Murchisoni (pars). Pusch. Polens Palaeontologie; S. 84; Taf. VIII, Fig. 11 a—b.
1842. Pholadomya exaltata. Agassiz; Myes; p. 72; pl. 4, fig. 7—8; pl. 4a.
1874. Phaladomya exaltata. Moesch. Pholadomyen; S. 56; Tab. XXI, Fig. 8; Tab. XXII, Fig. 1—3.
1892. Pholadomya exaltata (pars). Neumayr und Uhlig. Jurafossilien d. Kaukasus; S. 17.
1896. Pholadomya exaltata. Loriol. Mollusques et Brachiopodes de l’oxfordien du Jura Bernois; p. 59.

2 nuclei; thick rounded radial folds cover a large part of the surface of the shell. Sharp growth marks, crossing these folds, divide them into tubercles having a quadrangular form and elongated parallel to the axis of the shell. The posterior part of the shell, devoid of ribs, is small.

Similarities and differences: From Ph. Murchisoni (Moesch. Pholadomyen; S. 44; Tab. XVII, Fig. 6—9; Tab. XVIII—XIX) it differs in its thicker ribs and their tuberculate character. From Ph. subexaltata n. s. (see below) it differs in thicker ribs and an elongated form of the tubercles, as well as in the smaller dimensions of the posterior, ribless area. I think that only part of Ph. exaltata Neum. (l. c.) belongs here. In my material this form is fairly rare, whereas Neumayr indicates it as very common; moreover, Neumayr mentions that his Ph. exaltata passes into Ph. Murchisoni. These data lead one to think that Ph. exaltata Neum. belongs, for the most part, to the following species, which occurs very frequently (in masses) and shows characters bringing it close to Ph. Murchisoni.

Locality: Tsudakhar; Middle Callovian marly limestone (Bb). Ph. exaltata, according to Moesch, appears in the Callovian and lives until the Kimmeridgian; it is distributed in Poland, Swabia, Alsace, Switzerland, France.

51. Pholadomya subexaltata n. sp. (Plate II; fig. 11 a—b).

1. Pholadomya exaltata (pars?). Neumayr und Uhlig; Jurafossilien des Kaukasus; S. 17.

Dimensions:

Length	53.	53.	53.	50.	48.	45.	45.	40.	40.
Height	48.	46.	46.	47.	49.	47.	43.	41.	36.
Thickness	41.	40.	32.	43.	39.	37.	36.	34.	29.

27 nuclei. The outline is rather variable; in general more or less three-sided. The anterior margin is bluntly rounded; the upper posterior to the umbo is almost straight; the posterior is slightly truncated; the lower is rounded; the umbones are prominent. As in many other Pholadomya, on the anterior side there is a convex heart-shaped area, sharply

bounded off from the lateral sides of the shell. The lateral sides slope backward somewhat wedge-like. The surface is covered with radial ribs and concentric furrows. The radial ribs on the anterior side are developed in the number of 1–2, sometimes very weak; 1 rib always lies on the boundary between the anterior and lateral sides; 5–7 lie on the lateral sides; the posterior of these lateral ribs are always indistinct; their number may be more than 7, but then the hindmost are expressed only as a hint. Rather coarse concentric furrows divide the ribs into tubercles and give them a bead-like character; the tubercles are for the most part nearly round or square, more rarely elongated from top to bottom, and only the lowermost sometimes assume a form elongated from back to front, as in Phol. exaltata. The posterior area, devoid of ribs, is fairly large, although sharply separated from the ribbed flanks of the shell, since it bears, especially in the upper part, traces of ribbing. The gape is fairly narrow and long.

Affinities and differences. From Ih. exaltata it differs by its thinner ribs and by the broader and clearer posterior area devoid of ribs. Owing to the greater thinness of the ribs, the tubercles on them assume, instead of a form elongated from front to back, an equilateral form. From Ph. Murchisoni it differs by its coarser and sharper concentric furrows and by the distinctly bead-like character of the ribs resulting from this. The Caucasian species shows a tendency to form transitions both in one direction and in the other. Specimens with somewhat thicker ribs already resemble Ph. exaltata; specimens with weaker concentric lines resemble Ph. Murchisoni. The main mass of the Caucasian specimens, however, differs quite distinctly from both the one and the other. On the other hand, such specimens of Ph. Murchisoni as the one figured by Moesch on pl. XVII, fig. 8 of his monograph, or Ph. exaltata, figured there on pl. XXII, fig. 2, deviate so much from their types that the first might be taken for Ph. exaltata, and the second for my new form or even for Ph. Murchisoni. Hence follows the absence of sharp boundaries between the three species that interest us. Taking into account the Middle Callovian age of my form, the Oxfordian age of Ph. exaltata, and the Middle Jurassic age of Ph. Murchisoni, I consider it possible, with great probability, to regard my form as a Callovian or Middle Callovian mutation of a series that began in the Lower Dogger with Ph. Murchisoni and ended in the Upper Jurassic with Ph. exaltata. To avoid a new specific name for my form

it would have been possible only to unite Ph. exaltata with Ph. Murchisoni, which would scarcely have been advisable.

Locality. Tsudakhar: Middle Callovian marly limestone (Bb). Cited by Neumayr from Gunib and Koroda. I think that many citations of Ph. Murchisoni from the Callovian could belong to my species.

52. Pholadomya Murchisoni. Sow.

1. Pholadomya Murchisoni. Moesch. Pholadomyen; S. 44; Tab. XVII, Fig. 6—9; Tab. XVIII—XIX.
2. Pholadomya Murchisoni. Choffat. Faune Jurassique du Portugal; Lamellibranches; p. 22; pl. VI, fig. 4—10.
3. Pholadomya Murchisoni. Semenov. Mangyshlak; pp. 48 and 83.

For the remaining synonymy see Moesch and Choffat; for the Russian literature, Semenov.

To this species I assign 8 internal molds. The differences from the preceding forms are reduced to: 1) thinner ribs; 2) thinner and more frequent concentric lines; 3) the less distinct and finer tuberculation of the ribs resulting from this; the posterior ribless area is similar in character to that of the preceding species.

Locality: Tsudakhar; Middle Callovian marly limestone (Bb). Distributed throughout all Europe from the Bajocian to the Callovian stage inclusive.

53. Pholadomya Escheri. Ag. 1842.

1. Pholadomya Escheri. Agassiz. Myes; p. 102; pl. 7 f, fig. 16.
2. Pholadomya acuta. Agassiz. Myes; p. 70; pl. 4, fig. 1—3.
3. Pholadomya Escheri. Moesch. Pholadomyen; S. 50; Tab. XX, Fig. 12; Tab. XXI, Fig. 1—7.
4. Pholadomya Escheri. Choffat. Faune Jurassique du Portugal; p. 14; pl. V, fig. 2—7.

To this species belong, in my material, two incomplete internal molds of small specimens; they are characterized by an elongated form drawn out posteriorly and by finely tuberculate, thin ribs.

Locality: Tsudakhar; Middle Callovian marly limestone (Bb). Distributed in the Callovian deposits of Switzerland, Germany, France, and Poland.

54. Pholodomya crassa Ag. 1842.

1834–1840. Pholadomya ambigua (pars). Goldfuss. Petrefacta Germaniae; Tb. CLVI; Fig. 1 c.

1. Pholadomya crassa. Agassiz. Myes; p. 81; pl. 6 d, fig. 1—3.

2. Pholadomya texta. Agassiz. Myes; p. 81; pl. 4 b, fig. 7—9.

3. Pholadomya decussata. Agassiz. Myes; p. 74; pl. 4, fig. 9—10; pl. 4’, fig. 7—9.

4. Pholadomya crassa. Moesch. Pholadomyen; S. 42; Tab. XIV, Fig. 3; Tab. XVI. Fig. 1—4; Tab. XVII, Fig. 1—5.

5. Pholadomya crassa. Choffat. Faune Jurassique de Portugal; p. 21; pl. VI, fig. 1—3.

The 3 internal molds differ from Ph. Murchisoni in that behind the main rib there is formed a broad and fairly deep depression, in that they have fewer ribs, and in that these ribs are partly weakened and bear almost no distinct tubercles. I assign them to Ph. crassa, although the main rib in them is also sharply distinguished by its size. Being far from the typical central forms of Ph. crassa, these internal molds appear to be its varieties, more closely approaching Ph. Murchisoni.

Locality: Tsudakhar; Middle Callovian marly limestone (Bb). Distributed in the upper Bathonian and Callovian deposits of Poland, Germany, Switzerland, France, Portugal.

55. Pholadomya subcanaliculata n. sp. (Plate II; fig. 12).

Dimensions:

Measurement	Value
Length	46 mm.
Height	31 mm.
Thickness	23 mm.

Three internal molds of elongated form, rounded, somewhat narrowed posteriorly in outline, with weakly protruding umbones. The surface is covered with 11—12 thin and sharp ribs; of the latter, the 2—3 anterior ones bend somewhat forward; the 3rd or 4th is vertical, while the remaining—

… diverge backward. The posterior ribs are weakened, but nevertheless the entire surface of the shell remains ribbed. The anterior cordate field is indistinctly expressed.

Similarities and differences. In the character of the ribbing it resembles the Upper Jurassic Pholadomya canaliculata Roem. (Moesch. Pholadomyen; p. 63; Pl. XXIV, Figs. 1–9), but differs from the latter in its lesser height and less protruding umbones. In outline it resembles Pholadomya ovulum Ag. (Moesch. l. c.; p. 48; Pl. XX, Figs. 1–11), but the ribbing in my form is more sharply expressed. It probably represents a Kelloway mutation of these two species.

Locality. Tsudakhar; Middle Kelloway marly limestone (Bb).

56. Pholadomya rugosa n. sp. (Pl. II, Fig. 13; Pl. III, Fig. 14).

Dimensions:

Length	49.	45.	37.
Height	40.	43.	34.
Thickness	33.	32.	24.

Five internal molds of a form of rather variable outline, as is already evident from the measurements given. From rather elongated shells, resembling the preceding species in outline, there is a transition to high ones with almost equal height and length and with protruding umbones. The surface is covered with coarse concentric furrows and with rather numerous (up to 10), but very weak, barely noticeable radial ribs; the principal rib, running along the boundary of the indistinctly expressed anterior field, is better visible owing to the bend of the shell surface at this place.

Similarities and differences. I hesitated for a long time before accepting this form as a new species. The more elongated and lower specimens are very similar to some already described weakly ribbed species and weakly ribbed varieties of ribbed species. One of my specimens is very similar to Goldfuss’s illustration (Petrefacta Germaniae; Pl. CLII, Fig. 9) of Pholadomya concentrica Roem. (under the name Latrulia rugosa); but in my form there is no rounded edge running from the umbo to the posterior angle and depicted…

shown in Goldfuss’s figure, and moreover the posterior end in my form is more narrowed. Further, the same specimen is scarcely distinguishable from one of the illustrations of Pholadomya hemicardia Roem. in Moesch (Pholadomyen; Tab. XXIII, Fig. 1); from this illustration my specimen differs only in the more oblique position of the umbones. But whereas Roemer’s species, in its typical forms, is distinctly ribbed, in my form the ribs are never distinct and are completely obscured by the coarse concentric furrowing. My small specimen recalls the illustration of the same Ph. hemicardia in Fig. 5 of the same plate of Moesch, but its ribbing is weaker, and it is somewhat more elongate. Further, the same elongate variety of my form recalls Ph. ovulum Ag. (Moesch. l. c.; S. 48; Tab. XX, Fig. 1—11), but the concentric furrows in my form are coarser, and the length is less. The taller variety, in the character of its ribbing, may be compared with Phol. lineata Gldf. (Moesch. l. c.; S. 60; Tab. XXIII, Fig. 7—10), but it differs from it quite clearly in its outline: namely, when viewed in profile it does not show such a concavity on the upper margin behind the umbones as is visible in all the illustrations of Goldfuss’s species. As a result, taken as a whole, my form has nothing in common with Ph. hemicardia, likewise taken as a whole, and differs from the latter by its weaker ribbing and by a different outline. From Ph. ovulum my form is always distinguished by its lesser length, and from Ph. lineata by its outline. It is more difficult to distinguish it from Ph. concentrica, but this latter, apparently, does not attain as great a height as the tall variety of my form. I therefore believe that my form should be accepted as a new species and represents, perhaps, a Callovian mutation of Pholadomya lineata Gldf. It is difficult to say in what relation to my form stands the Phol. hemicardia that is cited from Korodag by Neumayr and Uhlig (Jurafossilien d. Kaukasus; S. 18); neither a description nor a figure of it is given, and weak ribbing is mentioned only with respect to two specimens out of the four assigned here by Neumayr.

Locality: Tsudakhar; Middle Callovian marly limestone (Bb).

Fam. Pleuromyacidae.

Genus Ceromya. Agassiz. 1841.

57. Ceromya calloviensis n. sp. (Plate III; figs. 16—17).

1. Ceromya excentrica. Neumayr und Uhlig. Jurafossilien d. Kaukasus; S. 19.

1. Ceromya excentrica (pars?). Papp in Dechy’s “Kaukasus”; Vol. III; p. 157; Pl. IV, Fig. 1?

Dimensions.

Length	.	.	.	90	88	82	75	68	68	57
Height	.	.	.	66	68	53	63	55	62	51
Thickness	.	.	.	71	61	52	56	53	52	43

25 internal molds. The outline is elongated trapezoidal on average, but in general rather variable. The form is strongly inflated, with thick rounded umbones. The hinge margin is almost straight; the anterior and lower margins are rounded; the posterior is obliquely truncated. The postero-dorsal part is separated from the rest of the shell by a depression and presents a certain likeness to an ear; the anterior surface recalls in character the heart-shaped anterior field of Pholadomya, but is not bounded off from the lateral sides by a groove. The sculpture consists of eccentric folds. These folds begin in front near the beaks; on the anterior cordate surface they diverge partly obliquely upward, partly horizontally, partly obliquely downward; then, along a certain line which may be taken as the boundary of the anterior surface, although it lies still on this latter, these folds bend obliquely downward and become almost parallel. The lower of them end on the lower margin; the middle ones bend, coming somewhat closer to a position parallel to the margin of the shell; the upper ones retain their direction rather unchanged; the middle and upper folds end along a certain line running obliquely backward from the umbones and marking the beginning of that depression which defines the posterior ear-like part of the shell; from here much smaller folds appear, running almost vertically and even slightly inclined upward and forward at an acute angle to the eccentric folds of the sides of the shell. On very large molds, traces of weak radial ribs appear; on some molds, near the postero-inferior end, traces of concentric growth marks are noticeable; I cannot establish the dependence of their occurrence on the size of the molds; contrary to Agassiz’s data on Cer. excentrica, I saw them more often on small specimens.

Similarities and differences: On the basis of the conditions of occurrence, I think that this is the very same form that was described by Neumayr and Uhlig as Ceromya excentrica. With insufficient preservation, to confuse it with

of this latter one very easily. In outline it differs from Cer. excentrica (Agassiz; Myes; pp. 28–32; pl. 8a, 8b et. 8c) only in the lesser length of the adult specimens, which, given the variability of the outline of Agassiz’s species, can scarcely be taken into account. The differences in sculpture are much more substantial. Agassiz’s species, with age, loses the eccentric sculpture on the casts, replacing it with a combination of concentric growth marks and weak radial sculpture. My species preserves the eccentric sculpture up to the greatest of the observed sizes, while radial or concentric sculpture is either absent or very indistinct. Further, both from the figures and from Agassiz’s description, the eccentric folds in his species terminate simply at the posterior and upper margins of the shell; in my species they do not reach this margin, but end abruptly along a certain inclined line, and on the posterior part of the shell they are replaced by another system of much finer folds, running toward them at an acute angle. I think that these data are sufficient to separate the Callovian form from the Kimmeridgian one. In sculpture my species is rather similar to Ceromya plicata Ag. (a Middle Jurassic species; Agassiz; Myes; p. 32; pl. 8 d. Morris and Lycett. Great Oolite Mollusca II; p. 107; pl. X, fig. 1–2). But the eccentric folds of my species do not show such bends on the sides of the shell as are depicted by Morris and Lycett; in my form these folds ascend more obliquely forward, and the outline is quite different: the beaks in my species project more, the lower margin is more convexly rounded, and the posterior margin is more obliquely truncated. Cer. excentrica in Papp’a (l. c.), judging from the figure, differs from my species in the wave-like bend of the folds on the sides and in the character of the ribbing behind the shell; but in the description its sculpture is compared with the illustration of Morris and Lycett, to which Papp’s figure is only slightly similar. Taking into account the very schematic character of Papp’s figure, I place his form, with a question mark, in the synonymy of mine. Probably my species represents the Callovian mutation of Phol. plicata and excentrica.

Locality. Tsudakhar; Middle Callovian marly limestone (Bb)—13 casts. Gunib; Callovian greenish marl (No. 1)—12 casts. It is cited in the literature from Korodag, Gunib, and, perhaps, from the Kuban region.

Genus Gresslya. Agassiz. 1842.

58. Gresslya trigonalis n. s. (Plate III; fig. 15).

Dimensions:

Length . . . . . . . . . . . . . . . 42.
Height . . . . . . . . . . . . . . . 30.
Thickness . . . . . . . . . . . . . . 25.

6 internal molds. A rather swollen, very inequilateral form of triangular outline; the umbones are situated far forward. The anterior and lower margins are rounded; the upper is slightly convex; the posterior passes into a sharp rounding connecting the upper margin with the lower. From the umbones to the posterior angle there extends a rounded edge, bounding, on the posterodorsal side, a convex area from the sides of the shell. The remains of the shell preserved on one of the internal molds show that the surface was covered with rather regular, fine and frequent concentric striae. On the right valve a groove characteristic of the genus is visible.

Similarities and differences. From all species of Gresslya known to me it differs very sharply in its triangular, strongly inequilateral form and in the strong development of the convex posterodorsal area. Gresslya rostrata Ag. (Myes; p. 211; pl. 12 b, fig. 7—9) has something in common with my form in the outline of the upper margin, but the anterior part in my form is still shorter, and the lower margin more convex.

Locality. Tsudakhar; Middle Callovian marly limestone (Bb).

59. Gresslya sp.

3 internal molds of a rounded, relatively short form with rather fine umbones. The groove on the right valve indicates their belonging to the genus Gresslya; determination of the species, however, proves impossible in view of the insufficiency of the material and the inadequate characterization of the species of Gresslya in the literature. Gresslya peregrina Phil. sp. (d’Orbigny. Prodrome I; p. 305 et 335) is, generally speaking, longer and more inequilateral. Shorter forms, such as Gresslya ventricosa Ag. (Myes; pl. 13, fig. 1—3), Gresslya cordiformis Ag.

(ibid. pl. 13a, fig. 5—7), Gresslya pinguis Ag. (ibid. pl. 13c, fig. 1—6), etc., differ in details of outline and are insufficiently characterized for it to be possible to see which of these details may be disregarded. Gresslya erucina Ag. (Myes; p. 217; pl. 13c., fig. 1—6) is very similar in outline to the Caucasian form, but is longer. If one follows Morris et Lycett (Great Oolite Mollusca. Supplement; p. 79) and unites together Gresslya erucina, peregrina, adducta, conformis, lunulata, latior, concentrica under the name Gresslya peregrina, then the Caucasian form could also enter into this collective type.

Locality. Tsudakhar; Middle Callovian marly limestone (Bb).

Genus Pleuromya. Agassiz. 1842.

60. Pleuromya Alduini. Gldf. sp.

1834—40. Lutraria Alduini. Goldfuss. Petrefacta Germaniae II; S. 255; Taf. CLII, Fig. 8.
1842. Pleuromya Alduini. Agassiz, Myes; p. 242; pl. 22, fig. 10—22.
1350. Panopaea Brongniartina. D’Orbigny. Prodrome I, p. 335.
1883. Pleuromya Brongniartina. Lahusen. Ryazanian Jura; p. 35.
1892. Pleuromya cf. Alduini. Neumayr u. Uhlig. Jurafossilien d. Kaukasus; S. 19.
1896. Pleuromya Alduini. Semenov. Mangyshlak; p. 50.

11 nuclei. I found no differences deserving attention from the figures of Goldfuss and Agassiz. This form should be subjected to critical revision in view of its extensive vertical distribution, but my material is insufficient for this purpose. Therefore, understanding it broadly, I refer the Caucasian specimens to it as well.

Locality. Tsudakhar; Middle Callovian marly limestone (Bb). Distribution very wide in the Dogger and Kelloway of all Europe, Russia, and the Transcaspian region.

61. Pleuromya varians. Ag. 1842.

1. Pleuromya varians, Agassiz; Myes; p. 247; pl. 25.
2. Pleuromya varians. Loriol. Mollusques et Brachiopodes de l’Oxfordien du Jura Bernois; p. 75; pl. XI, fig. 6.

1. Pleuromya varians. Papp in Déchy’s “Kaukasus” III; p. 158; pl. IV, fig. 3.

6 nuclei. A form very similar to the preceding one, but distinguished by a narrower and more pointed posterior end and by a very weak gape.

Locality: Gunib; Callovian greenish marl (No. 1). Distributed in the Oxfordian deposits of Switzerland.

Prionodesmacea.

Dysodonta.

Mytilacea.

Family Mytilidae.

Genus. Modiola. Lamark. 1801.

62. Modiola tulipaea. Lam.

1. Modiola tulipaea. Borissiak. Pelecypoda of the Russian Jurassic III; p. 2; pl. I, figs. 3—6.

For the synonymy see there; to it should be added:

1. Modiola Villersensis. Neumayr und Uhlig. Jurafossilien d. Kaukasus; p. 21.

2. Modiola tulipaea. Loriol. Mollusques et Brachiopodes du Jura Bernois; p. 118; pl. XV, figs. 1—2; synonymy there as well.

One fairly well-preserved specimen, in the sharp umbo, elongated form, and thickness, fully corresponds to this species as figured by Borissiak. Judging from the synonymy of Modiola Villersensis, the form cited under this name by Neumayr and Uhlig from Korodag must also belong here. The Caucasian specimen, in the development of the anterior auricle, approaches the Callovian variety of this form more closely than the Oxfordian one. It may be possible to separate them as distinct species, but, having only a single specimen, I consider it impossible to do so.

Locality. Tsudakhar; Middle Callovian marly limestone (Bb). Rather widely distributed in the Middle Jurassic, Callovian, and Oxfordian deposits.

63. Modiola plicata. Sow. 1821.

1. Modiola plicata. Sowerby. Mineral conchology III; p. 87; pl. 248, fig. 1.

1834—40. Mytilus plicatus. Goldfuss. Petrefacta Germaniae II; S. 175; Tab. CXXI, Fig. 12.

1. Mytilus Sowerbyanus. D’Orbigny. Prodrome I; p. 312.

2. Mytilus Sowerbyanus. Morris and Lycett. Great Oolite Mollusca II; p. 36; pl. IV, fig. 1.

1856—58. Mytilus Sowerbyanus. Oppel. Die Juraformation; S. 413

1. Modiola plicata. Quenstedt. Der Jura; S. 357; Tab. 49, Fig. 4.

2. Modiola Sowerbyana. Loriol et Schardt. Couches à Mytilus des Alpes Vaudoises; p. 63; pl. XI, fig. 9—12.

3. Modiola plicata. Benecke. Die Verstein. der Eisenerzformat. S. 168; Taf. IX, Fig. 6.

4. Modiola Sowerbyana. Borissjak. Pelecypoda of the Russian Jurassic III; p. 13.

9 specimens. One of them, with a length of 125 mm, has a width of only 28—30 mm and is somewhat curved. In general, however, considerable variability is observed in this respect. From Modiola perplicata Thurm. et Etall. (Borissjak; Pelecypoda of the Russian Jurassic III; p. 12; pl. II, fig. 6), this species is well distinguished by the thicker ribs on the dorsal part of the shell, which split into a larger number of fine branches. Better material may perhaps make it possible to distinguish the Callovian mutation as a separate species, but, given the considerable variability in my specimens, I am not in a position to fix definite distinguishing characters. Apparently, in general, the Caucasian form is longer than the other specimens figured in the literature, and the sculpture of its dorsal part is more sharply developed. Since the latter character depends strongly on the conditions of preservation, and the former is very variable (if one compares, for example, the figures of Goldfuss and Morris and Lycett), I do not venture to establish a new species on their basis.

Locality. Tsudakhar; Middle Callovian marly limestone (Bb). Rather widely distributed in the Middle Jurassic deposits of Europe.

Genus Lithophagus. Megerle. 1811.

64. Lithophagus? sp.

A poorly preserved internal mold of a very convex left valve with traces of the shell, bearing fine concentric grooves. Owing to its poor preservation I cannot compare it with any definite species. Even the generic determination, as based on the external form of the shell alone, appears doubtful.

Locality. Tsudakhar; Middle Callovian marly limestone Bb.

Genus Mytilus Linnée. 1758.

65. Mytilus sp.

A poorly preserved imprint of a small specimen, not permitting specific determination.

Locality. Tsudakhar; marly concretion from the Middle Jurassic clayey shale (Aa).

Pectinacea.

Fam. Limidae.

Genus Ctenostreon. Eichwald. 1867.

66. Ctenostreon pectiniforme. Schloth. sp. 1820.

1. Ostracites pectiniformis. Schlotheim. Petrefactenkunde; S. 231.
2. Lima proboscidea. Sowerby. Mineral conchology III; p. 115; pl. 264.
   1834—40. Lima proboscidea. Goldfuss. Petrefacta Germaniae II S. 88; Taf. CIII, Fig. 2.
3. Lima proboscidea. D’Orbigny. Prodrome I; p. p. 282, 312, 341.
4. Lima pectiniformis. Morris and Lycett. Great Oolite Mollusca II; p. 26; pl. VI, fig. 9.
   1856—58. Lima pectiniformis. Oppel; Die Juraformation; S. 414.
5. Ostrea pectiniformis. Quenstedt. Der Jura; S. 451; Tab. 59, Fig. 7.

1. Lima pectiniformis. Lucett. Great Oolite Mollusca; supplement; p. 39; pl. XXXIX, fig. 1.

2. Ctenostreon proboscideum. Eichwald. Lethaea Rossica II; p. 457.

1874—75. Lima proboscidea. Terr. Jurass. Sup. de Boulogne s. mer. II; p. 183.

1. Lima (Ctenostreon) pectiniformis. Neumayr u. Uhlig. Die Jurafossilien d. Kaukasus; S 27.

2. Ctenostreon pectiniforme. Semenov. Mangyshlak; p. 88.

3. Ctenostreon pectiniforme. Benecke. Eisenerzformation; S. 124; Taf I, Fig. 7.

4. Ctenostreon proboscideum. Loriol. Mollusques et Brachiopodes de l’Oxfordien du Jura Bernois; p. 125.

Fragments of 5 specimens. Neither in sculpture nor in form do they differ from Cten. pectiniforme, understood broadly; on the other hand, their mutual differences are no less than the small differences between the forms listed in my far from complete synonymy; a complete synonymy of this species could occupy pages.

To what extent it is possible to separate the Upper Jurassic and Middle Jurassic forms, I cannot judge. Loriol thinks that separation is impossible. Schlippe (Die Fauna des Bathonien im Oberrheinisch. Tieflande; S. 124) finds that this species lived up to the Oxfordian age, which presupposes the separation of the newer forms into a distinct species.

Occurrence. Tsudakhar; Kelloway limestone (Ac). Very widely distributed in the Middle and Upper Jurassic.

67. Ctenostreon sp.

A fragment of a thick valve, covered with round ribs. On the ribs the characteristic tubular appendages are well expressed. I consider the species indeterminate. The tubular appendages are better developed than on my specimens of Ctenostreon pectiniforme, and on the cited illustrations that follow, but nevertheless I do not consider its identification with that species entirely excluded.

Occurrence. Tsudakhar; Upper Jurassic limestone Db.

Genus Lima. Bruguière 1792.

68. Lima (Plagiostoma) duplicata. Sow. sp.; 1829.

1. Plagiostoma duplicatum. Sowerby. Mineral Conchology VI; p. 114; pl. 559, fig. 3.

1. Plagiostoma duplicatum. Phillips. Yorkshire; p. 112; pl. 6. fig. 2.

1834—1840. Lima duplicata. Goldfuss. Petrefacta Germaniae II; Tab. CII, Fig. 11.

1. Lima duplicata. d’Orbigny. Prodrome I; p. 341.

2. Lima duplicata. Morris and Lycett. Great Oolite Mollusca; p. 26; pl. III, fig. 6.

1856—58. Lima duplicata. Oppel. Die Juraformation; S. 414.

1. Plagiostoma duplicatum. Quenstedt. Der Jura; S. 435; Tab. 59, Fig. 15.

2. Lima Aalensis. Eichwald. Lethaea Rossica II; p. 469; pl. XX, fig. 14.

3. Lima duplicata Branco. Der untere Dogger v. Elsass—Lothringen; p. 112; Taf. VI, Fig. 5.

4. Lima duplicata. Lahusen. Ryazan Jurassic; p. 21; table I, fig. 13.

5. Lima (Radula) duplicata. Schlippe. Die Fauna d. Bathonien im Oberrhein. Tieflande; S. 119.

6. Lima (Mantellum) duplicata. Benecke; Die Eisenerzformation; S. 124; Taf. IV, Fig. 10.

One incomplete specimen. The roof-shaped ribs, the fine interstitial riblets in the furrows between the ribs, the fine signs of growth, and the threadlike riblets on the crests of the radial ribs fully correspond to what is observed in Lima duplicata. Minor differences may also be noted among the cited illustrations, but I am not able to fix any definite mutations.

Locality. Tsudakhar; Middle Callovian marly limestone (Bb). It is distributed rather widely in the Middle Jurassic, in the Callovian and, perhaps, Oxfordian stages.

69. Lima (Plagiostoma) cf. semicircularis. Gldf.

1834—40. Lima semicircularis. Goldfuss. Petrefacta Germaniae II; S. 83; Tab. CI, Fig. 6.

1. Lima semicircularis. D’Orbigny. Predrome I; p. 283.

2. Lima semicircularis. Morris and Lycett. Great Oolite Mollusca II; p. 29; pl. III, fig. 3.

1856—58. Lima semicircularis. Oppel. Die Juraformation; S. 415.

1. Lima cf. semicircularis. Loriol et Schardt. Couches à Mytilus des Alpes Vaudoises; p. 59; pl. X, fig. 1—4.

2. Plagiostoma semicirculare. Quenstedt. Der Jura; S. 415.

3. Lima semicircularis. Greppin. Fossiles de la Grande Oolite de Bâle; p. 125; pl. VI, fig. 12.

4. Lima (Radula) semicircularis. Schlippe. Die Fauna d. Bathonien im Oberrhein. Tieflande; S. 120.

5. Lima semicircularis. Neumayr und Uhlig. Die Jurafoss. d. Kaukasus; S. 29.

One specimen of a left valve. This species is very close to Lima Phillipsi d’Orb. (Pol. de la Russie; p. 478; pl. XLII, fig. 8). The latter, according to d’Orbigny, differs, however, from Goldfuss’s species by larger ribs, and my specimen in this respect is closer to Goldfuss’s species. D’Orbigny’s species, moreover, is somewhat longer than Goldfuss’s species. Schlippe indicates that the forms from the Cornbrash are longer than the forms from the Hauptoolith. With respect to length, as far as can be judged from my somewhat deformed specimen, the Caucasian form belongs rather to the long forms. I note, furthermore, that in the Caucasian specimen it is clearly visible how much the delicacy of the sculpture can be masked by conditions of preservation. Therefore I would be inclined to attach greater significance to the outline. As a result, I think that the Caucasian form represents a Callovian mutation of Lima semicircularis and most probably should constitute a separate species, but my material is insufficient for establishing it. It is possible that Lima Phillipsi in Lahusen (Ryaz. Jura; p. 22) is identical with the Caucasian form.

Locality. Tsudakhar; Middle Callovian marly limestone (Bb). Lima semicircularis is a widely distributed Middle Jurassic form; Lima Phillipsi is an Oxfordian form.

30. Lima (Limatula) subhelvetica n. sp. (Plate II; figs. 18—19).

Dimensions:

Length . . . . . . . . . . . . 35 mm.
Height . . . . . . . . . . . . 24 mm.

A swollen, only slightly oblique form with indistinctly delimited auricles. The middle of the valve is occupied by rather sharp radial riblets, about 12 in number; these ribs are thin and separated by wide

intervals; through the middle of these intervals pass thin riblets of the 2nd order; between these latter and the main ribs there are still thinner riblets of the 3rd order; these riblets of the 3rd order are somewhat irregular, are often not situated in the middle of the intervals, and in some intervals are entirely absent. Toward the anterior and posterior sides the main ribs become beveled, their outer side becomes broader than the inner; they are, as it were, pressed against the shell in front or behind toward the middle. Ribs of this character number about 4 on the posterior part of the shell, about 2 on the anterior part, and in the intervals between them there are only riblets of the 2nd order. Still closer to the anterior and posterior margin the normal ribbing is absent and is replaced by very fine folds, somewhat tile-like, overlapping one another in front and behind toward the middle of the shell. These folds are very numerous, but toward the margins of the shell they become indistinct.

Similarities and differences. This species recalls Lima helvetica Opp. (Die Juraformation; p. 489. Morris and Lycett; Great Oolite. Mollusca; supplement; p. 41; pl. XXXIII, fig. 8), from the Bathonian stage. The differences are reduced to the larger dimensions of my form, the greater number of intermediate riblets in it, the greater width of the intervals between the main ribs, and the greater height and thickness of the shell. Plagiostoma helveticum of Semenov (Mangyshlak; p. 66) might be identical with the Caucasian form. Lima subhelvetica probably represents a Kelloway mutation of Lima helvetica.

Locality. Tsudakhar; Middle Kelloway marly limestone (Bb).

Family Pectinidae.

Genus Hinnites. Defrance. 1821.

71. Hinnites cf. abjectus. Phill. sp.

1. Pecten abjectus. Phillips. Geology of Jorkshire; p. 162; pl. 9, fig. 37.

2. Hinnites velatus. Morris and Lycett. Great Oolite Mollusca; p. 14; pl. II, fig. 2.

3. Hinnites abjectus. Schlippe. Die Fauna d. Bathonien im Oberrhein. Tieflande; S. 135.

Fragments of 3 specimens. The sculpture consists of sharply rounded ribs, between which several weaker intermediate ribs appear. It shows great similarity to the cited illustration in Morris and Lycett, although the difference between the main and intermediate ribs is not so sharp.

I understand this species in the sense of Schlippe, thereby departing from Loriol’s point of view (Couches à Mytilus des Alpes Vaudoises; p. 72; pl. X, fig. 12–13).

Locality. Tsudakhar; Callovian limestone (Ac). Distributed in the Middle Jurassic of Europe.

Genus Pecten. Lamarck. 1799.

72. Pecten (Chlamys) fibrosus. Sowerby. 1818.

1. Pecten fibrosus. Sowerby. Mineral conchology. II; p. 84; pl. 136, fig. 2.

2. Pecten fibrosus. Phillips. Jorkshire II; p. 112; pl. 6, fig. 3.

1834—40. Pecten fibrosus. Goldfuss. Petrefacta Germaniae II; S. 46; Tab. XC, Fig. 6.

1. Pecten fibrosus. D’Orbigny. Palaeont. de la Russie, p. 476; pl. XLII, fig. 3—4.

2. Pecten fibrosus. D’Orbigny. Prodrome I; p. 341.

1856—58. Pecten fibrosus. Oppel. Die Juraformation; S. 568.

1. Pecten fibrosus. Lahusen. Ryazan Jurassic; p. 23; table II, fig. 3.

2. Pecten fibrosus. Neumayr u. Uhlig. Die Jurafossilien d. Kaukasus; S. 25.

16 specimens and fragments. They do not differ in any way from this well-known species. The number of ribs is about 10. Traces of concentric folds are often noticeable even on the internal molds. Pecten subfibrosus d’Orb. (Prodrome I; p. 373) seems to me to be based on excessively insignificant differences, and I think that this Oxfordian form should be united with Pecten fibrosus. The development of the concentric folds depends too much on the character of preservation, while the length in Pect. fibrosus is fairly variable.

Locality. Tsudakhar; Middle Callovian marly limestone (Bb). Gunib; Callovian greenish marl (No. 1).

Pudakhar; Callovian greenish marl (Ca). Distributed in the Callovian and Oxfordian deposits of Europe.

73. Pecten (Chlamys) subinaequicostatus n. sp.

(Table II; figs. 20–21).

1883, Pecten inaequicostatus. Lahusen. Ryazan Jurassic; p. 22; pl. I figs. 15–16.

Dimensions:

Height	40 mm.	30 mm.
Length	40 mm.	29 mm.

About 25 specimens. Outline almost circular. The right valve is convex, the left less convex, sometimes almost flat. The ears are almost equal; the posterior one rectangular, the anterior one with a notch for the byssus.

The sculpture on the right valve consists of broad, rounded radial folds, about 10 in number; these folds are separated by narrower grooves, of which the middle one is somewhat wider than the others. Near the apex, on the folds and in the grooves separating them, extremely fine radial striae are also visible. Growth marks are very fine, somewhat irregular, and very frequent. On the ears the sculpture consists of very frequent and fine riblets, parallel to the anterior margin of the anterior ear and to the posterior margin of the posterior ear.

The sculpture of the left valve consists of similar folds, but these folds are crossed by fine, though sharp, concentric folds. The latter are arranged at some distance from one another; sometimes they pass continuously across the grooves separating the radial folds, while at other times they are interrupted on these grooves; and often the little folds of one radial rib lie opposite the intervals between the folds of another. The sculpture of the ears is as on the right valve, but the riblets are somewhat sharper and coarser.

Similarities and differences: Pecten inaequicostatus Phill., judging from the figure (Geol. of Yorkshire; pl. 4, fig. 10), has still thicker folds and is an Upper Jurassic form. Pecten inaequicostatus Lycett (Great Oolite Mollusca; supplement; p. 32; pl. XXXIII, fig. 1) has much less numerous folds. Of Pecten cf. inaequicostatus Neum. and Uhl. (Jurafossilien d. Kaukasus; S. 25), in the absence of a figure, I can say nothing definite; the feature emphasized by the authors

The small number of ribs speaks, however, rather against identifying it with my form. Pecten inaequicostatus in Lahusen seems to me (from the figure) identical with my species. Pecten inaequicostatus in Semenov (Mangyshlak; pp. 63, 87), by locality, might also belong to my species. From Pecten fibrosus (see above) my species differs in its more broadly rounded folds and the narrower intervals between them. The left valve of my species recalls Pecten vagans Sow. (Min. Conch. VI; p. 82; pl. 543), but the right is entirely different.

Locality. Tsudakhar; Middle Kelloway marly limestone (Bb). It is probably rather widely distributed in the Kelloway deposits, but is confused with Pecten fibrosus and inaequicostatus.

74. Pecten (Chlamys) fibrosodichotomus. n. sp.

(Tab. II; fig. 22).

Dimensions:

Height	40 mm.
Length	42 mm.

Three specimens of the right valve. Its outline is almost circular; it is rather strongly inflated and has large, nearly equal ears; the posterior of them is rectangular, the anterior with a notch for the byssus.

The sculpture consists of broad, flatly rounded folds, similar to the folds of Pecten inaequicostatus. The number of these folds near the beak is 4–6, but already over the course of the upper third of the height of the shell they dichotomize, and their number becomes 8–12. The furrows separating the folds are narrower than the latter, the furrows separating the folds of the first order being wider and deeper than the furrows separating the folds of the second order; the most strongly developed of all is the furrow running along the median line of the valve. Concentric, fine, regular, and frequent growth marks cover the surface of the shell.

The ears are covered with fine, numerous riblets, parallel to the anterior margin of the anterior ear and to the posterior margin of the posterior ear.

Similarities and differences. The species is close to Pecten inaequicostatus and subinaequicostatus, but differs in its dichotomous ribs and strong median furrow.

Locality. Tsudakhar; Middle Kelloway marly limestone (Bb)—2 specimens. Gunib; Kelloway greenish marl (No. 1)—1 specimen. A small specimen, probably belonging here as well, was delivered by Prof. Stuckenberg from Gunib; the rock is similar to the Tsudakhar marly limestone (Bb).

75. Pecten (Entolium) demissus. Bean.

1. Pecten demissus. Phillips. Geology of Jorkhire II; p. 112; pl. 6, fig. 5.
   1834—40. Pecten demissus. Goldfuss. Petrefacta Germaniae II; S. 74; Tab. XCIX. Fig. 2.
2. Pecten demissus. D’Orbigny. Prodrome I; p. 341.
3. Pecten demissus. Morris and Lycett. Great Oolite Mollusca II; p. 127; pl. XIV, fig. 7.
4. Pecten demissus. Quenstedt. Der Jura; S. S. 353, 553; Tab. 48, Fig. 6—7. Tab. 72, Fig. 27.
5. Pecten demissus. Eichwald. Lethaea Rossica II; p. 426.
6. Pecten demissus. Lahusen. Ryazan Jurassic; p. 24; pl. II; fig. 4.
7. Pecten demissus. Schlippe. Die Fauna des Bathonien im Oberrhein. Tieflande; S. 126.
8. Pecten demissus. Semenov. Mangyshlak; p. 63.
9. Pecten (Entolium) demissus. Benecke; Die Eisenerzformation; S. 97; Taf. III. Fig. 8.

Seven specimens and fragments. I decidedly cannot distinguish them from Pect. demissus. From the synonymy of this species, which is very extensive, I cite only a small part, sufficient to characterize its distribution. Part of the forms under the names Pecten spatulatus, disciformis likewise belong here, but separating them presents great difficulties and requires abundant material. The outline, the form of the auricles, and the character of the surface fully correspond to Bean’s species.

Locality. Tsudakhar; Middle Kelloway marly limestone (Bb). This species is known from the Middle Jurassic, the Kelloway stage, and has been cited several times also from the Upper Jurassic. Gunib; Kelloway greenish marl—one doubtful specimen.

76. Pecten sp.

A fragment of a flat shell. The surface is covered with indistinct and irregular radial striae and fine concentric lines. It resembles certain species from the Russian Upper Jurassic (Portlandian, Aquilonian stages), cited under various names, but still very little studied.

Locality. Tsudakhar; Middle Callovian marly limestone (Bb).

Schizodonta.

Trigoniacea

Fam. Trigoniidae.

Genus Trigonia. Bruguière. 1789.

77. Trigonia sp.

The core of a small, flat specimen with a narrow, long posterior area. I consider determination of the species, and even a sufficiently well-founded comparison with known species, impossible.

Locality. Gunib; Callovian greenish marl (No. 1).

Ostracea.

Fam. Ostreidae.

Genus Exogyra. Say 1819.

78. Exogyra sp. ind.

One right and one left valve. The form is rather flat, almost kidney-shaped in outline. The muscular impression is almost semicircular, subcentral. The larger valve is attached by the greater part of its surface. The free part of the latter forms a vertically ascending rim.

Similarities and differences. In form it resembles Exogyra reniformis Gldf. (Petrefacta Germaniae; p. 34; pl. LXXXVI, figs. 6–7), but is much larger. The insufficient preservation and the small number of specimens do not permit an exact comparison. In my opinion, the kidney-shaped outline of the Caucasian form might also be an individual character, and only more extensive material could prove its specific significance.

Locality. Gunib; Callovian greenish marl (No. 1).

Genus Gryphaea. Lamark. 1801.

79. Gryphaea sp.

A small specimen of a left valve, narrowed near the beak and strongly expanded at the periphery of the shell. On the beak there is a pit for attachment. It might represent a young specimen of Gryphaea dilatata Sow. (Mineral Conchology II; p. 113, pl. 149).

Locality. Tsudakhar; Middle Callovian marly limestone (Bb).

80. Gryphaea Zudacharica n. sp. (Pl. II; fig. 23).

Only the left valve is known, in 2 (3) specimens. The form is strongly inflated, almost hemispherical, with a wing-like outgrowth on the large specimen and an almost imperceptible umbo. The adult is apparently free; the smaller specimen bears, near the umbo, an oblong narrow depression for attachment. The surface is covered with irregular growth marks. The third young specimen, which I assign here with some doubt, has a better-expressed umbo and was attached by the beak, as are all young gryphaeas. It strongly recalls Ostrea calceola Zieth., in Benecke (Die Eisenerzformation; p. 156; pl. XII, figs. 3–10).

Similarities and differences. From Gryphaea dilatata Sow. (Mineral Conchology II; p. 203; pl. 149) it differs in the almost complete absence of a beak and in its hemispherical form, as well as in less sharply marked growth signs. My form is more similar to some specimens of the Cretaceous Gryphaea vesicularis Lam.

Locality. Tsudakhar; Middle Callovian marly limestone (Bb).

Genus Ostrea. Linné. 1758.

81. Ostrea sp.

Fragments of large thick valves, not more precisely determinable.

Locality. Tsudakhar; Callovian limestone (Ac).

82. Ostrea sp.

A nucleus, not more precisely determinable.

Locality. Tsudakhar; Upper Jurassic limestone (Db).

Pteriacea.

Fam. Pteriidae.

Genus Oxytoma. Meek. 1864.

83. Oxytoma inaequivalve: Sow. sp. 1821.

1. Avicula inaequivalvis. Sowerby. Mineral Conchology III; p. 78; pl. 244, fig. 2—3.

1834—40. Avicula inaequivalvis. Goldfuss. Petrefacta Germaniae II; S. 130; Tab. CXVIII, fig. 1.

1834—40. Avicula Münsteri. ibidem; S. 131; Tab. CXVIII, Fig. 2.

1. Avicula inaequivalvis. D’Orbigny. Prodrome I; p. 341.

2. Avicula Münsteri. Morris and Lycett. Great Oolite Mollusca II; p. 129; pl. GIV, fig. 6.

1856—58. Avicula inaequivalvis. Oppel. Die Juraformation; S. 567.

1856—58. Avicula Münsteri. ibidem; S. 416.

1. Monotis Münsteri. Quenstedt. Der Jura; S. 440; Tab. 60, Fig. 6—9.

2. Avicula inaequivalvis. Lagusen. Ryazan Jura; p. 24; pl. II, fig. 5.

3. Avicula Münsteri. Greppin, Fossiles de la Grande Oolite de Bâle; p. 122; pl. IX, fig. 4.

1888, Avicula (Oxytoma) Münsteri. Schlippe. Die Fauna d. Bathonien im Oberrheinisch. Tieflande; S. 136.

1. Avicula Münsteri. Neumayr und Uhlig. Die Jurafossilien d. Kaukasus. S. 24.

2. Oxytoma inaequivalve. Benecke. Die Eisenerzformation; S. 91; Tab. IV, Fig. 11.

One left and one right valve, agreeing very well with the illustrations of Sowerby and Benecke. With the present state of our knowledge, I see no possibility of distinguishing Avicula inaequivalvis and Münsteri. Stratigraphically this separation is not carried out: forms like Sowerby’s figure are cited both from the Bajocian and from the Callovian. Nor, apparently, is it possible to make the separation morphologically, since the distinctive characters in the cited figures are combined in different proportions. In my left valve, already rather far from the beaks, between some of the principal ribs there appears one intermediate rib, and in this respect it very closely resembles Benecke’s figure (l. c.). In view of this, I prefer for the present to understand this species broadly. To it, probably, under such an interpretation, should also be referred Avicula digitata. Desl. (d’Orbigny; Prodrome I; p. 283).

Locality. Tsudakhar; Middle Callovian marly limestone (Bb). Distribution very broad. Known throughout the whole Middle Jurassic, including the Callovian. Hardly distinguishable forms are cited from the Lias.

Fam. Pernidae.

Genus Inoceramus. Sowerby. 1819.

84. Inoceramus cf. cordati. Uhl. sp. 1881.

1. Perna cordati. Uhlig. Die Jurabildungen v. Brünn; S. 171; Tab. XVII (V). Fig. 1—2,

2. Inoceramus cordati. Neumayr und Uhlig. Die Jurafossilien d. Kaukasus; S. 22.

One specimen, showing a very close resemblance to this species. The concentric lamellae, however, are not as regular as represented by Uhlig; moreover, my specimen is smaller than both of those illustrated by him. The structure of the valve is prismatic, as in Inoceramus, for which reason, at least with respect to the Caucasian form, the generic determination Perna is not applicable.

Locality. Tsudakhar; Middle Callovian marly limestone (Bb). Also known from the Lower Oxfordian deposits of Moravia.

Genus Gervillia. Defrance. 1820.

85. Gervillia aviculoides. Sow. sp. 1812.

1. Perna aviculoides. Sowerby. Mineral Conchology I; p. 147, pl. 66.

2. Gervillia aviculoides. Sowerby. Mineral Conchology VI; p. 16; pl. 511.

1834—40. Gervillia aviculoides. Goldfuss. Petrefacta Germaniae II; S. 123; Tab. CXV, Fig. 8.

1. Gervillia aviculoides. D’Orbigny. Paléontologie de la Russie; p. 477; pl. XLI, fig. 14—15.

2. Gervillia aviculoides. D’Orbigny. Prodrome I; p. 341.

1856—58. Gervillia aviculoides. Oppel. Die Juraformation; S. 607.

1. Gervillia aviculoides. Neumayr und Uhlig. Die Jurafossilien d. Kaukasus; S. 23.

11 fragments. Some, by the narrowness of the posterior auricle, approach Gervillia acuta Sow. (Mineral Conchology VI; pl. 510, fig. 5), but in general they are closer to Gervillia aviculoides.

Locality. Tsudakhar; Middle Callovian marly limestone (Bb)—7 fragments. Gunib; Callovian greenish marl (No. 1)—2 fragments. Tsudakhar; Callovian greenish marl (Ca)—2 fragments.

Fam. Pinnidae.

Genus Pinna. Linnée. 1758.

86. Pinna sp.

A fragment of a cast, not more precisely determinable.

Locality. Tsudakhar; Middle Callovian marly limestone (Bb).

Taxodonta.

Arcacea.

Family Parallelodontidae.

Genus Cucullaea. Lamark. 1801.

87. Cucullaea cf. subcancellata. Bor. 1905.

1. Cucullaea subcancellata. Borisyak. Pelecypoda of the Russian Jurassic II; p. 25; pl. III, fig. 14.

2 poor nuclei, which may have belonged to this form.

Locality. Tsudakhar; Middle Callovian Mergelistyi limestone (Bh). Described from the Middle Callovian of Tambov Province.

Molluscoidea.

Brachiopoda.

Telotremata.

Terebratulacea.

Family Terebratellidae.

Genus Waldheimia. King. 1850.

88. Waldheimia umbonella. Lam. sp. 1801.

1. Waldheimia umbonella. Davidson. British fossil Brachiopoda IV; p. 169; pl. XXII, fig. 7—8.

There, too, see the synonymy, from which it is probably necessary to exclude in part Ter. Rogeriana d’Orb., since this latter represents an Upper Jurassic form.

1 small specimen, in all essential respects similar to this species.

Locality. Tsudakhar; Middle Callovian marly limestone (Bb). A rather well-known Callovian form.

Fam. Terebratulidae.

Genus Terebratula. Klein. 1753.

89. Terebratula sphaeroidalis. Dav. 1851. mut. Balinensis. Neum. 1892.

1. Terebratula sphaeroidalis mut. Balinensis. Neumayr und Uhlig. Jurafossilien d. Kaukasus; S. 12.

See the literature there.

1 specimen, possessing the characteristic features of this form.

Locality. Tsudakhar; Middle Callovian marly limestone (Bb). Described from the Balin Oolite (Bathonien and Callovien) of Poland.

90. Terebratula maxillata. Sow. 1825.

1. Terebratula maxillata. Sowerby. Mineral Conchology V; p. 56; pl. 436, fig. 4.

2. Terebratula maxillata. Davidson. British fossil Brachiopoda I; p. 50; pl. IX, fig. 1—9.

3. Terebratula maxillata. Deslongchamps. Paléontologie Française; terrains jurassiques VI; p. 344; pl. 102—106.

4. Terebratula maxillata. Davidson. British fossil Brachiopoda IV; p. 121.

5. Terebratula maxillata. Davidson. British fossil Brachiopoda V; p. 264; pl. XX, fig. 12.

6. Terebratula maxillata. Haas. und Petri. Brachiopoden v. Elsass-Lothringen; S. 256; Taf. IX, Fig. 20; Taf. XI, Fig. 3, 9, 10, 16, 19; Taf. XII, Fig. 9.

7. Terebratula maxillata. Greppin. Fossiles de la Grande Oolite de Bâle p. 131; pl. IX. fig. 19.

For the remaining literature and synonymy see the works cited.

1 specimen, similar to the specimen from Corlibrasch figured by Deslongchamps (l. c. pl. 106, fig. 1).

Locality. Tsudakhar; Middle Cretaceous marly limestone (Bb). Known chiefly from the Bathonian stage.

91. Terebratula bissufarcinata. Schl. sp. 1820.

1. Terebratula bissufarcinata Quenstedt. Brachiopoden. Tab. 49, Fig. 22—23.
2. Terebratula bissufarcinata. Davidson. British fossil Brachiopoda IV; p. 124; pl. XV, fig. 1—3.
3. Terebratula bissufarcinata. Noetling. Jura v. Hermon; S. 38; Taf. VI, Fig. 1—3.
4. Terebratula bissufarcinata. Neumayr und Uhlig. Jurafossilien d. Kaukasus; S. 12.
5. Terebratula bissufarcinata. Haas. Jurass. Brachiop. des Schweizer. Jura; S. 127; Taf. XVIII, Fig. 1—6;

For the remaining literature see the authors cited.

5 specimens and fragments. Preservation rather poor, but all correspond very closely to this species.

Locality. Tsudakhar; Upper Jurassic limestone (Cc). Distributed chiefly in the Oxfordian deposits, but known also higher. 2 doubtful fragments—Tsudakhar; Upper Jurassic limestone (Da).

92. Terebratula subsella. Leym. 1846.

1. Terebratula subsella. Neumayr und Uhlig. Jurafossilien d. Kaukasus. S. 13.
2. Terebratula subsella. Haas. Jurass. Brach. des Schweiz. Jura; S. 137; Taf. XXI, Fig. 1—17.
3. Terebratula subsella. Semenov. Mangyshlak; p. 45; pl. I, fig. 8—9.

See the literature there as well.

13 specimens, rather small and often compressed, but entirely identical with this species both in outline and in the development of the lateral folds.

Locality. Tsudakhar; Upper Jurassic limestone. (Da)—12 spec. Tsudakhar; Upper Jurassic limestone (Db)—1 spec. Distributed rather widely in the Kimmeridgian stage.

Rhynchonellacea.

Fam. Rhynchonellidae.

Genus Rhynchonella. Fischer. 1809.

93. Rhynchonella moravica. Uhl. 1881.

1. Rhynchonella moravica. Uhlig. Die Jurabildungen in der Umgebung v. Brünn; S. 175; Tab. XVII, Fig. 6, 11.
2. Rhynchonella moravica. Noetling. Der Jura v. Hermon; S. 43; Taf. VII, Fig. 1—3.
3. Rhynchonella moravica. Neumayr und Uhlig. Die Jurafossilien d. Kaukasus; S. 7.

4 specimens and fragments. All belong to comparatively young individuals, and therefore the determination presents some difficulties; confusion with Rh. pectunculoides. Etall. is especially easy (Loriol et Pellat. Monographie des étages supérieures jurassiques de Boulogne sur Mer; p. 419; pl. XXVI, fig. 1—3); however, at the same dimensions Rh. pectunculoides has a much less distinctly expressed sinus and sharper umbonal ribs. My specimens are closest to Noetling’s broader variety. The septum is exactly the same as in the Moravian specimens.

Locality. Tsudakhar; Upper Jurassic limestone (Cb). Distributed in the Oxfordian stage.

94. Rhynchonella cf. inconstans. Sow. sp. 1821.

1. Terebratula inconstans Sowerby. Mineral Conchology III; p. 137; pl. 277, fig. 3—4.
2. Rhynchonella inconstans. Davidson. British fossil Brachiopoda I; p. 87; pl. XVIII, fig. 1—4.

1. Terebratula inconstans. Quenstedt. Brachiopoden; S. 136; Tab. 40, fig. 45—59.

2. Rhynchonella inconstans. Davidson. British fossil Brachiopoda. IV; p. 191, pl. XXVI, fig. 1—6.

3. Rhynchonella inconstans. Haas. Brachiopodes des Alpes Vaudoises; p. 107; pl. IX, fig. 1—2, 4, 7.

4. Rhynchonella inconstans. Haas. Jurass. Brach. des Schweizerischen Jura I; S. 16.

1 small specimen with weakly expressed asymmetry. I cannot distinguish it from Rh. inconstans.

Locality. Gunib; Upper Jurassic limestone. Distributed in the Kimmeridgian deposits.

95. Rhynchonella varians. Schl. sp. 1820.

1. Terebratulites varians. Schlotheim. Petrefactenkunde; S. 267.

2. Terebratula socialis. Phillips. Geology of Jorkshire I; p. 112; pl. 6, fig. 8.

3. Terebratula varians. Pusch. Polens Palaeontologie; S. 12; Taf. III, Fig. 3.

4. Terebratula varians. D’Orbigny. Paléontologie de la Russie; p. 480; pl. XLII, fig. 14—17.

5. Rhynchonella varians. D’Orbigny. Prodrome I; p. 376. et Rhynchonella Ziethemi p. 315.

6. Rhynchonella varians. Davidson. British fossil Brachiopoda. I; p. 83; pl. XVII, fig. 15—16.

1856—58. Rhynchnella varians. Opell. Die Juraformation; S. 498.

1. Terebratula varians. Quenstedt. Der Jura; S. 495; Tab. 66, Fig. 25.

2. Rhynchonella varians. Hofmann. Jura of the Iletskaya Defense; p. 18.

Rhynchonella varians. Eichwald. Lethaea Rossica II; p. 346.

1. Terebratula varians. Quenstedt. Brachiopoden; S. 85; Tab. 38, Fig. 56—82.

2. Rhynchonella varians. Davidson. British fossil Brachiopoda IV; p. 212; pl. XXVII, fig. 1—16.

3. Rhynchonella varians. Haas et Petri. Die Brachiopoden der Juraform. v. Els.—Lothr.; S. 229; Taf. VI, fig. 12—15; Taf. VII, fig. 21—23.

1. Rhynchonella varians. Lahusen. Ryazan Jurassic; p. 18; pl. I, fig. 4.

2. Rhynchonella varians et var. oolithica. Schlippe. Die Fauna des Bathonien im Oberrhein. Tiefl. S. 102.

3. Rhynchonella varians. Neumayr und Uhlig. Die Jurafossilien d. Kaukasus; S. 6.

4. Rhynchonella varians. Semenov. Mangyshlak; pp. 39 and 81, and Rh. cf. socialis p. 82.

59 specimens. It represents several varieties, closely connected with one another by transitions. In my material, var. socialis Phill. and var. spathica Davids. are rather typically represented. Some specimens approach Rh. spathica Lam. sp. (Neumayr und Uhlig, l. c.; S. 5; Taf. VI, Fig. 9—11), but are not, however, typical Rh. spathica. To distinguish Rh. socialis Phill. and Rh. varians Schl., as Semenov does, I see no possibility in my material: the outline of the frontal commissure and the strength of the ribbing vary so imperceptibly and gradually that, on the one hand, there are no two completely similar specimens, and on the other, any attempt at separation leads to more than half of the specimens remaining of uncertain affiliation. There are individual specimens that also recall the more ancient var. oolithica (Haas, l. c.; Schlippe l. c.).

Occurrence. Tsudakhar; Middle Callovian marly limestone (Bb)—55 specimens. Gunib; Callovian greenish marl (No. 1)—3 specimens. Tsudakhar; Callovian greenish marl (Ca)—1 specimen. This species is distributed from the Bathonian to the Oxfordian stage.

96. Rhynchonella concinna. Sow. sp. 1812.

1. Terebratula concinna. Sowerby. Mineral Conchology I, p. 192; pl. 83, fig. 6.

2. Terebratula flabellula et rostrata. Sowerby. Mineral Conchology VI; pp. 67, 71; pl. 535, fig. 1; pl. 537, fig. 1.

3. Rhynchonella concinna. Davidson. British fossil Brachiopoda, I; p. 88; pl. XVII, fig. 6—12.

1856—58. Rhynchonella concinna. Oppel. Die Juraformation; S. 499.

1. Rhynchonella concinna. Terquem et Jourdy. Moselle; p. 136.

2. Terebratula concinna. Quenstedt. Brachiopoden; S. 80, 92, 143; Tab. 38; Fig. 36; Tab. 40, Fig. 63—67.

1. Rhynchonella concinna. Davidson. British fossil Brachiopoda IV; p. 205; pl. XXVII, fig. 22–23.

2. Rhynchonella concinna. Haas und Petri. Die Brachiopoden der Juraform. v. Els.—Lothr. S. 218, Taf. VI, Fig. 3—4.

3. Rhynchonella concinna. Greppin. Fossiles de la Grande Oolite de Bâle; p. 131.

4. Rhynchonella concinna. Schlippe. Die Fauna d. Bathonien im Oberrh. Tieflande. S. 100.

5. Rhynchonella cf. concinna. Neumayr und Uhlig. Jurafossilien. d. Kaukasus; S. 6.

6. Rhynchonella concinna. Semenov. Mangyshlak; p. 40.

1 specimen. The sinus of the ventral valve is somewhat narrower than normal, and its development may be somewhat great for so small a specimen as mine (20 mm long). Both these differences pertain to so-called normal specimens of Rh. concinna, but unquestionably do not exceed the limits of variation of the species.

Locality. Tsudakhar; Callovian limestone (Ac). The species is chiefly Bathonian, partly Callovian.

Vermes.

Annelida.

Tubicola.

Genus Serpula. Linnée. 1758.

97. Serpula gordialis. Schl. sp. 1820.

1. Serpulites gordialis. Schlotheim. Petrefactenkunde; S. 96.

1826—33. Serpula gordialis et Serpula flaccida. Goldfuss. Petrefacta Germaniae I; S. 234; Tab. LXIX, Fig. 7—8.

1. Serpula gordialis et Serpula flaccida. Quenstedt. Der Jura; S. 393; Tab. 53; Fig. 16.

2. Serpula gordialis. Lahusen. Ryazan Jura; p. 18.

3. Serpula gordialis et flaccida. Semenov. Mangyshlak; pp. 36, 38.

Rather numerous tubes of various sizes on two fragments of oysters. Serp. gordialis and flaccida differ only in size. Among the Caucasian specimens there are tubes as small as Serp. gordialis, and as large as Serp. flaccida, and, moreover, tubes of intermediate size. Therefore I do not consider it possible to maintain these two forms as separate species.

Locality. Tsudakhar; Kelloway limestone (Ac); the geological distribution of this species is very wide, and its limits are very indefinite. It is cited from all stages of the Middle and Upper Jurassic.

Echinodermata.

Echinozoa.

Echinoidea.

Euechinoidea.

Spatangoida.

Cassidaloidea.

Fam. Collyritidae.

Genus Collyrites. Des Moulins. 1835.

98. Collyrites elliptica. Des Moulins. 1835.

1. Collyrites elliptica. Cotteau. Paléontologie Française; Terrains Jurassiques IX; p. 58; pl. X, XI, XII.

See the synonymy there as well.

1. Collyrites elliptica. Spendiaroff. Ueber einige Seeigel aus dem Jura d. Kaukasus; S. 203.

5 specimens, of which two are in fragments. They differ in no way from this well-known species.

Locality. Tsudakhar; Middle Callovian marly limestone (Bb). Distributed in Callovian and partly Bathonian deposits of France, Switzerland, and Southern Germany.

Cidaroida.

Fam. Cidaridae.

Genus Cidaris. Klein. 1734.

99. Cidaris sp.

A fragment of a spine, not more precisely determinable.

Locality. Tsudakhar; Upper Jurassic limestone (Db).

Pelmatozoa.

Crinoidea.

Articulata.

Fam. Eugeniacrinidae.

Genus Eugeniacrinus. Miller. 1821.

100. Eugeniacrinus sp.

Fragments of a stem; I consider the species indeterminable.

Locality. Tsudakhar; Callovian limestone (Ac)

Coelenterata.

Cnidaria.

Anthozoa.

Hexacoralla.

Aporosa.

Fam. Astraeidae.

Genus Cyathophora. Michelin. 1841.

101. Cyathophora Bourgueti. Defr. sp. 1821.

1. Cyathophora Bourgueti. Becker und Miloschewitch. Die Korallen der Nattheimer Schichten; S. 149; Taf. XXXVII, Flg. 5.

See the synonymy there.

1 specimen, not differing in any way from this species.

Locality. Gunib. Delivered by Prof. Stuckenberg. Probably comes from the Upper Jurassic limestone. Widespread in Upper Jurassic deposits. A form difficult to distinguish occurs also in the Middle Jurassic.

102. Cyathophora Stuckenbergii n. sp. (Pl. II; fig. 24).

Fragment of a compound polypidom of irregular shape. Diameter of the calyx about 2½ mm; distance between calyces about 1 mm. Three cycles of septa can be distinguished in 6 systems, gradually decreasing in size. Twenty-four rather thick ribs are located on the outer sides of the cells; the ribs of adjacent cells sometimes merge.

Similarities and differences. The smaller diameter of the cell distinguishes this species from Cyath. Bourgueti. From Cyath. magnistellata. Beck. (Die Korallen der Nattheimer Schichten; S. 150; Tab. XXXVII, Fig. 6) my form differs, besides the indicated character, also in its not quite equal calyces and in the smaller number of ribs.

Locality. Gunib; supplied by Pr. Stuckenberg and probably comes from Upper Jurassic limestone.

Spongiae.

Remains of sponges are not rare, chiefly in the Upper Jurassic limestones, but also occur in the Middle Jurassic. I have two rather indeterminate specimens: 1) from Tsudakhar; Upper Jurassic limestone (Db); 2) likewise from Tsudakhar; Callovian limestone Ac.

In one of the siliceous concretions from the Upper Jurassic (Cb) of Tsudakhar, under the microscope I saw indistinct remains resembling Radiolaria.

IV.

CONCLUSION.

For the precise determination of the age of the fauna described, the greatest significance is possessed by that part of it which was collected in the gray marly limestones of Tsudakhar—Vv., since this part is the most abundant. From there I have 66 forms, namely:

1. Belemnites cf. Calloviensis. Opp,
2. Belemnites sp.
3. Cosmoceras Pollux. Rein. sp.
4. Cosmoceras aculeatum. Eichw. sp.
5. Cosmoceras Zudacharicum n. sp.
6. Cosmoceras Daghestanicum n. sp.
7. Oecoptychius aff. refractus. Rein. sp.
8. Aspidoceras diversiforme, Waag.
9. Peltoceras chauvinianum d’Orb. sp.
10. Ataxioceras Abichi. Neum. sp.
11. Perisphinctes? (Procerites?) sp. ind.
12. Perisphinctes (Procerites) aberrans. Waag.
13. Perisphinctes calvus. Sow. sp.
14. Perisphinctes (Grossouvria) cf. poculum. Leck. sp.
15. Perisphinctes (Grossouvria) Comptoni. Pratt. sp.
16. Perisphinctes (Grossouvria) cf. Balinensis. Neum.
17. Perisphinctes (Grossouvria) cf. variabilis. Lah.
18. Perisphinctes (Grossouvria) Rossicus. Siem.
19. Hecticoceras lunula. Ziet. sp.
20. Hecticoceras pseudopunctatum. Lah.
21. Natica cf. globosa. Morr. et Lyc.
22. Turbo? sp.

1. Pronoëlla Calloviensis n. sp.
2. Pronoëlla cf. Loweana. Morr. et Lyc.
3. Pronoëlla cf. depressiuscula. Morr. et Lyc.
4. Isocardia tenera. Sow.
5. Arcomya Caucasica n. sp.
6. Arcomya inaequivalvis n. sp.
7. Arcomya cf. inflata. Terqu. et Jourd.
8. Arcomya dubia n. sp.
9. Goniomya sulcata. Ag.
10. Goniomya V—scripta. Sow. sp.
11. Pholadomya exaltata. Ag.
12. Pholadomya subexaltata n. sp.
13. Pholadomya Murchisoni. Sow.
14. Pholadomya Escheri. Ag.
15. Pholadomya crassa. Ag.
16. Pholadomya subcanaliculata n. sp.
17. Pholadomya rugosa n. sp.
18. Ceromya Calloviensis n. sp.
19. Gresslya trigonalis n. sp.
20. Gresslya sp.
21. Pleuromya Alduini. Gldf. sp.
22. Modiola tulipaea. Lam.
23. Modiola plicata. Sow.
24. Lithophagus? sp.
25. Lima (Plagiostoma) duplicata. Sow. sp.
26. Lima (Plagiostoma) aff. semicircularis. Gldf.
27. Lima (Limatula) subhelvetica n. sp.
28. Pecten (Chlamys) fibrosus. Sow.
29. Pecten (Chlamys) subinaequicostatus n. sp.
30. Pecten (Entolium) demissus. Bean.
31. Pecten (Chlamys) fibrosodichotomus n. sp.
32. Pecten sp.
33. Gryphaea sp.
34. Gryphaea Zudacharica n. sp.
35. Oxytoma inaequivalve. Sow. sp.
36. Inoceramus cf. cordati. Uhl. sp.
37. Gervillia aviculoides. Sow. sp.
38. Pinna sp.
39. Cucullaea cf. subcancellata. Bor.
40. Waldheimia umbonella. Lam. sp.
41. Terebratula sphaeroidalis. Dav. mut. Balinensis Neum.

1. Terebratula maxillata. Sow.
2. Rhynchonella varians. Schl. sp.
3. Collyrites elliptica. Desm.

The 24 forms determined as sp., or as new species, or finally known only from Dagestan (Ataxioceras Abichi), have no significance for determining the age. Of the remainder, 42–33 are Callovian. The remaining 9 forms are in part species from the Dogger: Pronoëlla cf. depressiuscula, Arcomya cf. inflata, Modiola plicata, Lima aff. semicircularis, Terebratula maxillata; in part Upper Jurassic: Inoceramus cf. cordati, Goniomya sulcata; while for the remaining two the stratigraphic position is insufficiently known (Natica cf. globosa, Terebratula sphaeroidalis mut. Balinensis). If it is noted that the Upper Jurassic forms are in part (Inoc. cf. cordati) determined only as cf., and in part (Gon. sulcata) are species with little-studied vertical distribution; that the Bathonian forms are in part determined as cf. and aff. (Pronoëlla cf. depressiuscula, Arcomya cf. inflata, Lima aff. semicircularis) and in part (Modiola plicata, Terebratula maxillata) are species with a rather indefinite vertical distribution; then it will be clear that the Upper Jurassic and Middle Jurassic elements have only negligible significance in the fauna under consideration, and the entire assemblage of the fauna of limestone B in Tsudakhar must be regarded as Callovian. Of the Callovian ammonites of this fauna (14 in all), 13 are known from the Middle Callovian, and only one (Perisphinctes cf. poculum) is an Upper Callovian form—and even that is determined only as cf. Hence, it seems to me, one may without forcing matters conclude that the layer under consideration has a Middle Callovian age. The same age, judging by the rock, is possessed by Astarte undata. Gldf. sp., supplied from Gunib by Mr. Stukenberg, as well as by two ammonites found washed out along the road from Khodzhal-Makhi to Tsudakhar.

1. Erymnoceras Renardi. Nik. sp.
2. Perisphinctes (Procerites) Indicus. Siem.

Upon limestone B in Tsudakhar lies a greenish limestone Ca with

1. Pecten (Chlamys) fibrosus. Sow.
2. Gervillia aviculoides. Sow. sp.
3. Rhynchonella varians. Schl. sp.

a fauna which, in general, also indicates the Callovian age of this rock. I was unable to collect more fossils from it owing to

owing to the inconvenient character of the exposure and the lack of means at my disposal at the time of visiting it. But an entirely similar rock was encountered by me under more favorable conditions at Gunib (in the foothills), and in it I succeeded in collecting the following 19 forms:

1. Cosmoceras Gulielmi. Nik. (non Sow.).
2. Cosmoceras subornatum n. sp.
3. Peltoceras athleta. Phill. sp.
4. Peltoceras annulosum. Qu. sp.
5. Perisphinctes (Grossouvria) Comptoni. Pratt. sp.
6. Perisphinctes (Grossouvria) Rossicus. Siem.
7. Hecticoceras pseudopunctatum. Lah. sp.
8. Ammonites sp.
9. Pronoëlla Calloviensis n. sp.
10. Pronoëlla cf. depressiuscula. Morr. et Lyc. sp.
11. Isocardia tenera Sow.
12. Ceromya Calloviensis n. sp.
13. Pleuromya varians. Ag.
14. Pecten (Chlamys) fibrosus. Sow.
15. Pecten (Chlamys) fibrosodichotomus n. sp.
16. Trigonia sp.
17. Exogyra sp.
18. Gervillia aviculoides. Sow. sp.
19. Rhynchonella varians. Schl. sp.

This fauna is very close to the fauna of Bb at Tsudakhar and contains 11 species in common with it. However, this fauna already contains such a characteristic Upper Callovian form as Peltoceras athleta and the Oxfordian (already less important) Pleuromya varians. The remaining species have either a Callovian character in general (the greater part) or a Middle Callovian character (Cosmoceras Gulielmi. Nik. (non Sow.). Therefore I suppose that this greenish limestone is in any case not younger than the base of the Upper Callovian, and since it overlies the limestone Bb at Tsudakhar, this latter also, stratigraphically, cannot be younger than the Middle Callovian.

Beneath the limestone Bb at Tsudakhar there lies directly a yellowish marl Ac with

1. Cosmoceras macrocephali n. sp.
2. Macrocephalites macrocephalus. Schl. sp.

1. Natica? sp.
2. Pleurotomaria sp.
3. Isocardia n. sp. ind.
4. Astarte aff. rotunda d’Orb.
5. Ctenostreon pectiniforme. Schl. sp.
6. Hinnites abjectus. Phill. sp.
7. Ostrea sp.
8. Rhynchonella concinna, Sow. sp.
9. Serpula gordialis. Schl. sp.
10. Eugeniacrinus sp.

For determining the age, both ammonites are important here. Cosm. macrocephali is a new species, if Cosm. Jason Rein. is understood in Teisseyre’s narrow sense, and should be referred to Cosm. Jason if this latter species is understood in the broad sense of Nikitin, who united with it Cosm. subnodatum Teiss. Consequently this form indicates the middle Callovian. But Macroc. macrocephalus is a guiding lower-Callovian form. Consequently the marl Ac of Tsudakhar cannot be older than the upper beds of the lower Callovian, which likewise definitely indicates a middle-Callovian age for the limestone Bb of Tsudakhar.

The beds lying below the Callovian marl Ac are represented in my material by only an insignificant number of forms. From the “geoden-terrain” of Gunib I have only

Parkinsonia Parkinsoni. Sow. sp.

From a concretion in the clayey shale Aa of Tsudakhar:

Mytilus sp.

Taken together with the stratigraphic data, all this indicates a Middle Jurassic age in the broad sense and, in any case, not younger than lower Callovian for these beds.

The limestones lying above the greenish limestone Ca of Tsudakhar likewise provide only little data for determining their age. The limestone Cb with

Belemnites sp.

could be Callovian or Oxfordian.
The limestone Cc with

Terbratula bissufarcinata. Schl. sp.
Rhynchonella moravica. Uhl.

may be Oxfordian.

Limestone Da with

Terbratula subsella. Leym.

is quite probably Kimmeridgian.

Limestone Db with

Ctenostreon sp.
Ostrea sp.
Terbratula subsella. Leym.
Cidaris sp.

could be Kimmeridgian or Tithonian. To all these determinations of age, based on such forms as Brachiopoda, I do not, however, attach great significance. The geological distribution of Jurassic Brachiopoda has not been very well studied; their species often pass through several stages, and their determination is rather difficult and almost always leaves room for some doubt. In my opinion, it can be said with certainty only that the limestones occurring above Ca of Tsudakhar represent the upper series, beginning with the Oxfordian stage and perhaps including part of the Upper Callovian as well. From the Gunib Upper Jurassic limestones I have only

Rhynchonella cf. inconstans. Sow. sp.

And to these same limestones could also belong the two corals supplied by Prof. Stuckenberg,

Cyathophora Bourgueti. Defr. sp.
Cyathophora Stuckenbergі n. sp.

Comparing these results with the data of the older authors, we see that

1) the limestones Cb, Cc, Pa, and Pb of Tsudakhar correspond to the limestones of Abich’s upper stage, all the more so since they also contain siliceous concretions and gypsum, as Abich also indicates.

2) The same limestones correspond to Kimmeridgien, Corallien, and Oxfordien in Sjögren. His Oxfordien is characterized by segregations of flint and chalcedony, which also appear in the limestone Cb of Tsudakhar.

3) The gray marly limestones of Ca and Bb of Tsudakhar, No. 1 of Gunib and Ac of Tsudakhar correspond to Sjögren’s Kellovian and to those impure limestones of Abikh which lie at the base of his upper stage of the Dagestan Jurassic. Consequently, the age of this horizon of Abikh is purely Kellovian.

4) Reuz’s section is not applicable to the part of Dagestan that I visited, since in it the “geodenterrain,” which in Reuz embraces the Middle Kellovian, is more ancient and in any case not newer than the lower part of the Lower Kellovian.

5) Uhlig’s results are inaccurate in that he sees in Abikh’s impure limestones the Kellovian, Oxfordian, and Kimmeridgian, whereas these limestones are entirely Kellovian, as Sjögren had already quite correctly concluded earlier.

Reuz’s results are based mainly on the study of the more southerly parts of Dagestan. The Kellovian species he cites from the “geodenterrain,” Stephanoceras coronatum, Hecticoceras lunula, and Hecticoceras hecticum, are not separated by him stratigraphically from Bathonian and even Bajocian forms. If one notes that in K. Bogdanovich the Kellovian Hecticoceras lunula and punctatum are cited together with the Bajocian Lioceras concavum and even below the latter, it becomes clear that some confusion exists here. Either some Kellovian forms occur in Dagestan in lower horizons than is usually thought; or, in the identifications, some closely related species were confused. If one notes that Stephanoceras coronatum, in the sense of its stratigraphic significance, is also not a very reliable form, then with regard to southern Dagestan one must admit that the Kellovian there still has to be found and distinguished stratigraphically. For the part of Dagestan in which I was, this part of Reuz’s section is completely inapplicable.

The divergence of my results from Uhlig’s results I ascribe to the fact that Uhlig was not himself on the spot and attached exaggerated significance to some individual species with insufficiently studied distributions. The equivalence of my Kellovian and, perhaps even more precisely, of the Middle Kellovian of the lower part of Abikh’s upper stage in Uhlig is proved not only by the numerous species in common, but also by their relation in terms of the abundance of specimens. The Oxfordian stage is proved by Uhlig here on the basis of 4 forms, of which two are new, one is known also in the Kellovian, and only one is purely Oxfordian (Inoceramus cordati). This last ...

the form has hitherto been known from only a very limited number of localities, and its geological distribution can hardly be considered precisely fixed.

The evidence for the Kimmeridgian stage is based on three species. Of these, Ceromya excentrica has apparently been identified inaccurately, on the basis of insufficiently preserved specimens. Ataxioceras Abichi is an exclusively Dagestanian species and cannot serve for determining the age. Ferisphinctes polyplocus aud. is a form so difficult to determine, and of such uncertain significance, that I likewise do not consider it possible to base anything upon it.

There remains also the Oxfordian–Kimmeridgian Pholadomya hemicardia. It is absent from my material, although there is a specimen of my new species Ph. rugosa, almost indistinguishable from certain varieties of Ph. hemicardia. I also do not consider this form a sufficient argument for determining the age. Further, Uhlig emphasizes the complete identity of the rock in which the shells of the horizon that interests us were preserved. Since, in the character of its fauna, this horizon corresponds to my Middle Callovian, while my Upper and Lower Callovian differ distinctly petrographically, then, unless one admits the possibility of mixtures in Uhlig, his fauna also cannot stratigraphically contain elements of the Oxfordian or Kimmeridgian stages.

Thus the stratigraphic result of my present article amounts to this: for the middle and upper Jurassic, the age of its separate parts in the Gunib and Dargin districts of Dagestan was correctly determined by Sjögren, and subsequent investigations have shown his results to be fairly accurate. In addition, in my article there is determined, as it seems to me, the relationship of the three principal Callovian zones for the part of Dagestan studied by me.

The Callovian fauna of the locality studied gives further occasion for rather interesting general historico-geological considerations. Unfortunately, “circumstances beyond my control” compel me to finish this work sooner than I should have wished. Therefore, leaving to geologists who find themselves in happier circumstances the strict conduct of argumentation for or against, I confine myself only to the almost dogmatic expression of that conviction to which I came while studying my material, the literature, and those collections which I had occasion to examine for comparison.

The Callovian fauna presented must be considered from two points of view: provincial and facial. By the provincial character of the fauna I mean only those of its features which dis—

are caused by the partitioning of marine basins, I believe that, in order to establish provincial differences, faunas of the same facies character must be compared. The provincial character of the Callovian fauna of Dagestan is then defined as distinctly Central European, or, still more closely, Central Russian. The admixture of Indian elements (Perisphinctes aberrans, Aspidoceras diversiforme, and a few others) is very small and, given the present state of our knowledge, can hardly be assessed from the standpoint of its significance. The complete absence of characteristic Mediterranean elements is a rather puzzling fact if one compares the fauna described with the fauna of other parts of the Caucasus and of the immediately older Jurassic deposits of Dagestan. In the Callovian of the central Caucasus, and in the Bathonian and Bajocian stages of Dagestan, Mediterranean elements play a far more prominent role. It seems to me that the explanation of this circumstance should be sought in the insufficient validity of Neumayr’s division of the European Jurassic into provinces. This division is now already in need of revision and, as was indicated in part earlier by some geologists (Kilian for the Lower Cretaceous), contains within itself a confusion of provincial features with facies ones. A detailed substantiation of this conviction of mine is at present impossible for me.

As regards the facies character of the Callovian fauna under consideration, I must first of all note that, for determining this character, the most essential thing is the comparison of the abundance of individuals of the various forms. From this standpoint, the middle Callovian is characterized by an abundance of forms and by the small number of specimens of each ammonite form.

Almost all their species have been found in only a single specimen, but the number of species reaches 18—a rather large figure in comparison with the total number of 66 forms. It is also worth noting the paucity of belemnites. The group that stands out by its abundance in the fauna under consideration is the so-called Mya-like forms, i.e. the genera Pholadomya, Arcomya, Ceromya, Gresslya, Pleuromya. The abundance of this group (16 species and about 90 individuals) gives the fauna a very distinctive character; especially striking in this respect is the abundance of Pholadomya. Also characteristic is the abundance of one species of Pecten and of Rhynchonella varians. Since I had almost no time to extract the shells on the spot and collected the rock chiefly in pieces, these ratios are fairly close to the actual ratios in nature. Grouping the species now according to the number of individuals, we obtain:

1. More than 20 individuals yielded

2. Rhynchonella varians. Schl. sp. 55 specimens.

3. Pecten subinaequicostatus n. sp. 25 specimens.

4. Pholadomya subexaltata n. sp. 25 specimens.

5. More than 10 individuals, but fewer than 20.

6. Pecten fibrosus, Sow.

7. Pleuromya Alduini. Gldf. sp. 11.

8. Ceromya Calloviensis n. sp. 13.

9. More than 5 individuals, but fewer than 10.

10. Gervillia aviculoides. Sow. sp. 7.

11. Pecten demissus. Bean 7.
12. Modiola plicata. Sow. 9.
13. Gresslya trigonalis n. sp. 6.
14. Pholadomya Murchisoni. Sow. 8.

15. Pronoëlla Calloviensis n. sp. 6.

16. 5 individuals

17. Collyrites elliptica. Desm.

18. Pholadomya rugosa n. sp.
19. Pronoëlla cf. Loweana. Morr. et Lyc. sp.
20. Ataxioceras Abichi Neum. sp.

The remaining species were found by me in fewer than 5 specimens.

Such a character of this fauna, in complete harmony with the character of the rock, which contains a rather large amount of sand as an admixture, indicates that the fauna under consideration is, in any case, not a fauna of the open sea and, in facies terms, resembles many Jurassic faunas known especially from Switzerland, but also extending northward, as, for example, in England and Northern Germany (the abundance of Pholadomya, Ceromya, Pecten of the fibrosus group). However, this facies proper in the Callovian rocks has been studied very little, although many occurrences of it are known from the Bathonian, Oxfordian, and even Kimmeridgian ages. Hence arises the external similarity with some Upper Jurassic faunas, which led, for example, Uhlig to suppose an Upper Jurassic age for part of this fauna. A detailed study of the distribution of this facies, which might provide points of support for determining its physico-geographical significance, is impossible for me under the present circumstances.

The Upper Callovian fauna of the part of Dagestan under consideration bears an already somewhat different facies character. Pholadomya here almost disappears, and among the bivalves only Ce

...romya and Pleuromya. Also fairly frequent are Isocardia tenera and one species of Pronöella.

The rock, together with this, becomes somewhat less clayey. Still higher up there already appear fairly frequent limestones with siliceous concretions and rare fossils. Still higher, gypsum appears in the limestones. It is difficult to assess the significance of this change, owing to my lack of faunistic data.

The beds older than the middle Kellaways have a more sandy character, and in places even contain pebbles. Their fauna does not contain myacites, but Ctenostreon and Hinnites are rather numerous in it. All this gives these beds the features of a littoral formation.

Thus, in the studied part of the Dagestan Jurassic we have a transition from a sandy calcareous littoral formation, through a myacite marl-limestone facies, to fairly pure, poorly bedded limestones with siliceous concretions, and then with gypsum.

Compelled to interrupt my work, I confine myself to what has been said above. In essence, it represents only the posing of certain questions and an indication of the direction in which, as it seems to me, the answers to them should be sought. Leaving the investigation of these answers to persons placed in more favorable conditions, I merely draw attention to the enormous importance, for the knowledge of the history of the earth, of studying individual geological formations from the faunistic point of view, if, in studying the fauna, one takes into account not only the so-called index forms, but its entire assemblage.

Only by studying the whole assemblage of forms of a given locality that are capable of being preserved in the fossil state can we reconstruct the general picture of their relationships and thus find a point of support for judging the conditions under which the given rock arose.

It seems to me that, by the examples of Uhlig and Reuz, I have shown how easily one may err even in determining the age, if one relies upon a small number of forms compared with similar forms from distant localities, and not upon the whole assemblage of the fauna.

Résumé

In this work I describe the fossils that I collected in 1903 in the Jurassic of Daghestan, and set forth the stratigraphic and geological conclusions resulting from my study of these fossils.

The Jurassic of Daghestan had been studied by several geologists, but their results are rather contradictory; it seems to me that my study removes one of these contradictions.

In 1862 Abich¹) had divided the Jurassic of Daghestan into three stages. His upper stage was composed of limestones and dolomites, underlain by impure limestones with numerous fossils (Ammonites coronatus, canaliculatus, Ceromya excentrica etc.). His middle stage contained the “geodenterrain,” that is to say, shales and sandstones “with argillaceous-siliceous spheroids sometimes containing fine ammonites and other fossils.” This stage was assigned by Abich to the Brown Jurassic.

In 1889 Sjögren²) published a more detailed division. In the limestones and dolomites of Abich’s upper stage he distinguished the Kimmeridgian, the Corallian, and the Oxfordian. The impure limestones at the base of this stage he assigned to the Callovian. The “geodenterrain” of the middle stage is assigned to the Bathonian and Bajocian.

In 1892 Uhlig³) found in Sjögren’s impure Callovian limestones elements of the Callovian, the Oxfordian, and the Kimmeridgian. The “geodenterrain” still remains for him the Bathonian and the Bajocian.

¹) “Sur la structure et géologie du Daghestan.” Mémoires de l’Académie des sciences de Saint Pétersbourg. VII série, t. IV, No. 10.

²) “Uebersicht der Geologie Daghestans und Terek-Gebietes.” Jahrbuch der K. K. Geologischen Reichsanstalt. B. XXXIX; S. S. 418—438.

³) Neumayr und Uhlig. “Ueber die von H. Abich im Kaukasus gesammelten Jurafossilien.” Denkschrifte der Wiener Akademie B. LIX; S. S. 1—122.

In 1904 Reuz¹ found in this “geodenterrain” the Bajocian, the Bathonian, and the lower and middle Callovian; Abich’s “impure limestones” are not recognizable in his divisions.

But Abich says of these impure limestones that they “make it possible to establish a very precise geognostic horizon across Daghestan.” We have seen that this very precise geognostic horizon is treated now as the Callovian (Sjögren), now as a complex of the Callovian, Oxfordian, and Kimmeridgian (Uhlig), and now is not recognized (Reuz).

It seems to me that I can establish the stratigraphic position of this horizon.

On the localities of the fossils described.

The fossils described in this work were collected:

1. Near Zoudakar (Dargo district), almost 1 kilometer south of the village. There I observed the following section.

Beneath the limestones and sandstones of the Lower Cretaceous one sees there:

Db. A whitish limestone with Ctenostreon sp., Ostrea sp., Terebratula subsella Leym., Cidaris sp. (Kimmeridgian or Tithonian).

Da. A gray limestone with Terebratula subsella Leym. (Kimmeridgian?)

Cc. A gray crystalline limestone with gypsum, Terebratula bissufarcinata Schl. sp. and Rhynchonella moravica Uhl.

Cb. A gray limestone with siliceous concretions; remains of sponges (Oxfordian?)

Ca. A greenish limestone with Pecten fibrosus Sow.; Gervillia aviculoides Sow. sp., Rhynchonella varians Schl. sp. (Upper Callovian).

Bb. A gray marly limestone with subordinate beds of a gray clay. This limestone contains numerous fossils of the Middle Callovian.

Ba. Talus.

Ac. A marly and sandy limestone with a few pebbles and Macrocephalites macrocephalus Schl. sp., Cosmoceras macrocephali n. sp., etc. (An upper bed of the Lower Callovian).

Ab. Clays and clayey shales with a rather thick bed of compact marl.

Aa—A clayey shale with very rare fossils (Mytilus sp.).

1. Near Gunib (No. 1), in a greenish limestone resembling the Ca limestone of Zoudakar, I collected fossils of the upper and middle Callovian: Peltoceras athleta Phill. sp., Cosmoceras aculeatum Eichw. sp., etc.

2. Near Gunib, at a lower level, I found a fragment of a marly concretion with Parkinsonia Parkinsoni Sow. sp.

3. At Gunib, Prof. Stuckenberg collected several Jurassic fossils whose occurrence was not indicated more precisely. The mode of preservation of an Astarte undata resembles the Ab limestone of Zoudakar; that of a Perisphinctes subtilis Neum. the Ac limestone of Zoudakar; and that of a Cyathophora Bourgueti Defr. and a Cyathophora Stuckenbergï n. sp. the limestones of the Upper Jurassic.

4. On the road from Kadjal Maka to Zoudakar I found two Callovian ammonites: Erymnoceras Renardi Nik. and Perisphinctes indicus Siem. The mode of preservation resembles the Bb limestone of Zoudakar.

List of fossils with descriptions of the new species.

1. Belemnites cf. calloviensis Opp. Zoudakar Bb—1 ex.

2. Belemnites sp. Zoudakar Bb—1 ex.

A fairly large phragmocone at an angle of 35°.

1. Belemnites sp. Zoudakar Cb—1 ex.

A poorly preserved fragment of a conical rostrum; it somewhat resembles Bel. quinquesulcatus Blainv. (Mémoire sur les bélemnites; p. 83; pl. 2, fig. 8); but the occurrence excludes this species.

1. Cosmoceras Pollux Rein. sp. Zoudakar Bb—1 ex.

2. Cosmoceras aculeatum Eichw. sp. Zoudakar Bb—1 ex.

3. Cosmoceras Gulielmi Nik. (non Sow.). Gunib No. 1—1 ex.

It is distinguished from Cosm. Gulielmi Sow. sp. by the coarser ribs (see Miner. Conchol. IV; p. 5; pl. 311), but it is identical with that described as Cosm. Gulielmi by S. Nikitin (Die Jura-Ablagerungen zw. Rybinsk etc.; p. 94; pl. IV, fig. 31—in Russian) and as Cosm. Iason by I. Lahusen (Rjäsan; p. 576; pl. IV, fig. 29).

1. Cosmoceras subornatum n. sp. Gunib No. 1—1 ex. (pl. I, fig. 1 a—b).

I have only a fragment. The discoidal shell; its diameter was about 80 mm; height of the last whorl above the suture—34 mm, above the preceding whorl—25 mm; thickness of the last whorl—27 mm; the adult whorls high; the back scarcely rounded, bounded by two rounded edges; the umbilical edge is poorly defined; the ribs are numerous, divided into 2–3; at the boundary of the lower third of the height of the whorl they form, as it were, elongated lateral tubercles; then they weaken before their division; the ribs cross the back without interruption or weakening, or without forming perceptible marginal tubercles.

The young whorls resemble those of Cosm. ornatum. The septa are poorly preserved and have nothing particular about them.

Close to Cosm. ornatum Schl. sp. (O. S. Nikitin; Die Jura-Ablagerungen. zw. Rybinsk. etc.; pl. VII, fig. 34—in Russian), it differs from it by its higher whorls in adults, by a smaller umbilicus, finer ribs, a broader, scarcely rounded back, and by its being ornamented with ribs that are not interrupted or weakened. Cosm. enodatum Lah. (non Nik.) loses its tubercles and its dorsal furrow at a much younger age than my species.—The figures of Ammonites ornatus in Quenstedt (Die Ammoniten des Schwäbischen Jura; Tab. 83, Fig. 25; Fab. 84, Tig. 13) in part resemble my species, but show much more distinct marginal tubercles.

1. Cosmoceras Zudacharicum n. sp. Zoudakar Bb—1 ex. (pl. I, fig. 2a–b).

A fragment; the shell discoidal; the whorls high, the back almost flat; the lateral ribs slightly convex; the umbilical edge rounded; the ribs, coarser than those of the preceding species, divide into 3 branches; these branches usually unite in threes at the marginal tubercles; the umbilical and lateral tubercles are elongated, but distinct; from each marginal tubercle there starts a rib, which crosses the back without interruption or weakening and joins the tubercle of the opposite side. The septa are not characteristic.

The union of the ribs at the marginal tubercles occurs in Cosm. Duncani Sow. sp. (Mineral Conchology II; p. 129; pl. 157) and sporadically in Cosm. Proniae Teiss. (Rjäsan; p. 557; pl. III, fig. 15–18); but my species is distinguished from both by its broad back, ornamented with ribs passing without interruption or weakening, and by the union of the ribs at the marginal tubercles in threes.

1. Cosmoceras Daghestanicum n. sp. Zoudakar Bb—1 ex. (pl. I, fig. 3a—b.).

A fragment; the shell discoidal; the diameter of the shell was 70—80 mm; height of the last whorl above the suture—30 mm; thickness of the last whorl—17 mm; the back flat; the lateral sides slightly convex; the numerous ribs divide into 3—4 branches; the umbilical tubercles elongated; the lateral tubercles round and distinct; there are intercalated ribs; outwardly the ribs thicken somewhat; sometimes they unite in twos at the marginal edge; the marginal tubercles not perceptible; the septa are not preserved.

This species is close to Cosm. subnodatum Teiss. (Rjäsan; p. 549; Taf. II, fig. 9—11), to Cosm. Jason Rein. sp. (=Cosm. Gulielmi Lahusen; “Rjäsan”; pl. VIII, fig. 7—in Russian), to Cosm. Proniae Teiss. l. c.; p. 557; Taf. III, Fig. 15—18), but is distinguished from all by its broad back, ornamented with continuous and not weakened ribs.

1. Cosmoceras macrocephali n. sp. Zoudakar Ac—1 ex. (pl. I, fig. 4 a—b).

Dimensions: diameter of the shell—27 mm = 1.00; of the umbilicus—11 mm = 0.41; height of the last whorl above the suture—11 mm = 0.41; above the preceding whorl—9 mm = 0.33; thickness of the last whorl—7 mm = 0.26. The shell discoidal, compressed; the back bears a smooth groove; the ribs divide into 2—3 branches; there are intercalated ribs; the umbilical and lateral tubercles almost imperceptible; the marginal tubercles small but distinct. The septa are of the type of Cosm. Jason.

Close to Cosm. enodatum Lah. (Rjäsan; p. 55; pl. VI, fig. 9—in Russian; the true Cosm. enodatum Nik. has infinitely finer ribs), it differs from this species by its higher whorls and its compressed back.

From Cosm. Jason Rein. sp. (Lahusen; Rjäsan; p. 57; pl. VII, fig. 7 named Cosm. Gulielmi) and Cosm. subnodatum Teiss. (Rjäsan; p. 549; pl. II, fig. 9—11) it differs by the almost complete absence of lateral and umbilical tubercles.

1. Oecoptychius aff. refractus Rein. sp. Zoudakar Bb—1 ex. A fragment. From Oecoptychius refractus Rein. sp. and Oecoptychius refractus macrocephali Quenst. sp. (Die Ammoniten des Schwäbischen Jura; p. 766; Tab. 81, Fig. 51—52) it is distinguished by a much more open angle of its last chamber with the rest of the shell.

2. Parkinsonia Parkinsoni Sow. sp. Gounib; “Géodenterrain”;—1 ex.

3. Aspidoceras diversiforme Waag. Zoudakar Bb—3 ex.

4. Peltoceras athleta Phill. sp. Gounib No. 1—1 ex.

1. Peltoceras chauvinianum d’Orb. sp. Zoudakar Bb—1 ex.

2. Peltoceras annulosum Quenst. sp. Gounib No. 1—1 ex.
   (V. Quenstedt; Die Ammoniten des Schwäbischen Jura II; p. 784; Pl. 88, Fig. 22).

3. Ataxioceras Abichi Neum. sp. Zoudakar Bb—5 ex.

4. Perisphinctes? (Procerites?) sp. ind Zoudakar Bb—1 ex.

A specimen with a diameter of 150 mm. The young whorls resemble those of Aspidoceras diversiforme. The adults are adorned with simple and coarse ribs on the lateral sides; their dorsum is almost smooth. It may also be a Peltoceras or Aspidoceras.

1. Perisphinctes (Procerites) aberrans Waag. Zoudakar Bb—1 ex.

Waagen’s figure (Cutch—Cephalopoda; pl. XLI, fig. 1—2) is erroneously named Per. spirorbis, but the description (ibid. p. 175) is correctly entitled; this error is corrected by M. Siemiradzki (Monographie d. Perisphinctes; p. 305), but M. Noetling (Jurassic Fauna of Baluchistan I; p. 21; pl. XIII, fig. 1) repeats it.

1. Perisphinctes (Procerites) Indicus Siem. The Kadjal–Maka–Zoudakar road—1 ex.

2. Perisphinctes calvus Sow. sp. Zoudakar Bb—3 ex.

3. Perisphinctes (Grossouvria) cf. poculum Leck. sp. Zoudakar Bb—1 ex.

4. Perisphinctes (Grossouvria) Comptoni Pratt. sp. Zoudakar Bb—3 ex. Gounib No. 1—1 ex.

5. Perisphinctes (Grossouvria) cf. Balinensis Neum. Zoudakar Bb—1 ex.

6. Perisphinctes (Grossouvria) cf. variabilis Lah. Zoudakar Bb—1 ex.

7. Perisphinctes (Grossouvria) Rossicus Siem. Zoudakar Bb—2 ex. Gounib No. 1—1 ex.

8. Perisphinctes (Grossouvria) subtilis Neum. Gounib (deposit unknown)—1 ex.

9. Erymnoceras Renardi Nik. sp. The Kadjal–Maka–Zoudakar road—1 ex.

I unite Stephanoceras Renardi Nik. (Jura v. Elatma; p. 120; Pl. II, Fig. 24) and Ammonites coronoides Quenst. (Die Ammoniten des Schwäbischen Jura II; p. 777; Pl. 87, Fig. 34—37). I believe that their temporary union is compelled by our insufficient knowledge of these species.

1. Macrocephalites macrocephalus Schl. sp. Zoudakar Ac—1 ex.

2. Hecticoceras lunula Zieth. sp. Zoudakar Bb—2 ex.

1. Hecticoceras pseudopunctatum Lah. sp. Zoudakar Bb—3 ex.; Gounib No. 1—1 ex.

2. Ammonites (Haploceras?) sp. Gounib No. 1—1 ex.

3. Natica cf. globosa Morr. et Lyc.? (non Boem?) Zoudakar Bb—1 ex.

4. Natica? sp. Zoudakar Ac—1 ex.

The general form resembles that of Natica Calypso d’Orb. (Terrains jurassiques II; p. 202; pl. 292, fig. 9—10), but is distinguished by the presence of very faint spiral sculpture.

1. Turbo? sp., Zoudakar Bb—1 ex.

Resembles Turbo Erinus d’Orb. (Terrains jurassiques II; p. 362, pl. 336, fig. 12—14), but the latter is from the Corallian.

1. Pleurotomaria sp. Zoudakar Ac—1 ex.

2. Pronoëlla Calloviensis n. sp. Zoudakar Bb—6 ex; Gounib No. 1—2 ex. (pl. I, fig. 5 a—b).

The molds are large and thick; the beaks almost in the middle; the upper margin concave in front, rising obliquely backward; the anterior and lower margins rounded; the posterior margin somewhat truncated; from the beak to the postero-inferior angle runs a convexity; pallial line with a small sinus.

Resembles Venus grandis Münst. (Goldfuss; Petrefacta Germaniae II; S. 245; Tab. CL. Fig 15), but is longer and has the anal side more obtuse and the lunule smaller.

1. Pronoëlla cf. Loweana Morr. et Lyc. sp. Zoudakar Bb.—5 ex.

2. Pronoëlla cf. depressiuscula Morr. et Lyc. sp. Zoudakar Bb—3 ex; Gounib No. 1—6 ex.

3. Isocardia tenera Sow. Zoudakar Bb—2 ex; Gounib No. 1—6 ex.

4. Isocardia n. sp. ind. Zoudakar Ac.—1 ex.

Resembles in its general form Isocardia tenera, but the concave anterior side is not delimited by a distinct ridge.

1. Astarte undata Gldf. sp. Gounib (locality unknown)—1 ex.

2. Astarte aff. rotunda Morr. et Lyc. sp. Zoudakar Ac.—1 ex.

3. Arcomya Caucasica n. sp. Zoudakar Bb—1 ex. (pl. I, fig. 6).

Form rather large and elongate; the beaks anterior; a rounded convexity running from the beak to the postero-inferior angle bounds a concave postero-superior area; two almost straight ridges bound a corselet characteristic of the genus; hiatus rather small; the surface of the mold shows only traces of growth marks.

Resembles Arcomya Clapensis Terqu. et Jourd. (Moselle; p. 79 pl. VI, fig. 1—4), but is more elongate, and the corselet narrower, the

the ridges bounding the corselet straighter, the postero-superior area more distinct. Arcomya Castroi Choff. (Faune Jurassique du Portugal; p. 36; pl. I, fig. 4–5) has the anal part more expanded, is more compressed anteriorly, and has the hooks situated more anteriorly.

1. Arcomya inaequivalvis n. sp. Zoudakar Bb—1 ex. (pl. I, fig. 7 a—b).

Elongate and compressed form; the postero-superior area is narrow; the corselet of the right valve is broader than that of the left valve; the surface of the cast shows only traces of growth marks.

It resembles Arcomya cornuta Terqu. et Jourd. (Moselle; p. 78; pl. VII, fig. 1—3), but is distinguished by its more compressed and elongate form. Arcomya Cortazari Choff. (Faune Jurassique du Portugal; p. 37; pl. I, fig. 7) has a broader postero-superior area.

1. Arcomya cf. inflata Terqu. et Jourd. Zoudakar Bb—2 ex. (pl. II, fig. 9).

2. Arcomya dubia n. sp. Zoudakar Bb—1 ex. (pl. I, fig. 8).

Elongate and compressed form; the posterior part somewhat expanded; the corselet is only indistinctly bounded; the surface of the cast shows traces of rather coarse concentric sculpture.

It closely resembles Arcomya aequalis Terqu. et Jourd. (Moselle; p. 77; pl. VI, fig. 9—10), but the anterior part of my species is more expanded and there is no concavity in the middle of the lateral side, as figured by Terquem and Jourdy.

1. Goniomya sulcata Ag. Zoudakar Bb—2 ex.

2. Goniomya quinquescripta Sow. sp. Zoudakar Bb—1 ex.

3. Pholadomya exaltata Ag. Zoudakar Bb—2 ex. (pl. II, fig. 10).

4. Pholadomya subexaltata n. sp. Zoudakar Bb—27 ex. (pl. II, fig. 11 a—b).

Related to Pholad. exaltata Ag. and Pholad. Murchisoni Sow.; from Pholad. exaltata my species is distinguished by its narrower ribs and their round or vertically elongated tubercles; from Pholad. Murchisoni my species is distinguished by thicker ribs and their more distinct tubercles. This is Pholad. exaltata Neum. et Uhl. (Jurafossilien d. Kaukasus; S. 17), but it resembles Pholad. Murchisoni no less than Pholad. exaltata, and, taking these two species into account, the Caucasian form must be regarded as a distinct species.

1. Pholadomya Murchisoni Sow. Zoudakar Bb—8 ex.

1. Pholadomya Escheri Ag. Zoudakar Bb—2 ex.

2. Pholadomya crassa Ag. Zoudakar Bb—3 ex.

3. Pholadomya subcanaliculata n. sp. Zoudakar Bb—3 ex. (pl. II, fig. 12).

Rounded form, somewhat narrowed posteriorly; the beaks not very elevated; the surface adorned with 11–12 fine and sharp ribs; the posterior ribs weakened.

Close to Pholad. canaliculata Boem. (Moesch; Pholadomyen; p. 63; XXIV; fig. 1—9), it is distinguished from it by its less elevated beaks. Pholad. ovulum Ag. (Moesch; l. c., p. 48; pl. XX, fig. 1—11) has the ribs less distinct.

1. Pholadomya rugosa n. sp. Zoudakar Bb—5 ex. (pl. II; fig. 13—14).

Variable form, the surface adorned with rather coarse concentric furrows and nearly 10 very weak radial ribs. Close to Pholad. lineata Gldf. (Moesch; Pholadomyen; p. 60; pl. XXIII, fig. 7—10), it is not so high and has the posterior part of the upper margin not so concave.

1. Ceromya Calloviensis n. sp. Zoudakar Bb—13 ex.; Gounib No. 1—12 ex. (pl. II, fig. 16—17).

General form variable and resembles Cer. excentrica Ag. (Myes p. 28; pl. 8a, 8b, 8c); but the eccentric ribs of my species are predominant in shells 90 mm long; the concentric and radial ornamentations are almost invisible; the eccentric ribs end at a line running from the beak obliquely backward and downward; after this line one sees the other, finer ribs directed obliquely upward and backward at an acute angle to the eccentric ribs; this sculpture resembles Cer. plicata Ag. in Morris and Lycett (Great Oolite Mollusca II; p. 107; pl. X, fig. 1—2); but the beaks of my species are more elevated, the general form is entirely different, and the eccentric ribs are not so curved toward the lateral ribs.

1. Gresslya trigonalis n. sp. Zoudakar Bb—6 ex. (pl. II, fig. 15).

A swollen species, very inequilateral and subtrigonal; the remains of the shell show a very fine concentric sculpture; a rounded convexity determines a convex postero-superior area and

disposed entirely on the upper side of the shell. This form is distinguished from all known species by its subtrigonal form and by its very short anterior side.

1. Gresslya sp. Zoudakar Bb—3 ex.

A species resembling Gressl. erycina Ag. (Myes; p. 217; pl. 13, fig. 1—6), but shorter. It also resembles Gr. ventricosa Ag. (ibid.; pl. 13, fig. 1—3),—Gr. cordiformis Ag. (ibid.; pl. 13a, fig. 5—7), Gr. pinguis Ag. (ibid.; pl. 13c, fig. 1—6), while always differing in details of form; without a revision of all these rather poorly known species it is impossible to decide whether this form is a new species or should be united with one of the species named.

1. Pleuromya Alduini Gldf. sp. Zoudakar Bb.—11 ex.
2. Pleuromya varians Ag. Gounib No. 1—6 ex.
3. Modiola tulipaea Lam. Zoudakar Bb—1 ex.
4. Modiola plicata Sow. Zoudakar Bb—9 ex.
5. Lithophagus? Sp. Zoudakar Bb.—1 ex.
6. Mytilus sp. Zoudakar Aa—1 ex.
7. Ctenostreon pectiniforme Schloth. sp. Zoudakar Ac—5 ex.
8. Ctenostreon sp. Zoudakar Db—1 ex.

The tubular prolongations of the ribs are more distinct than those of Ct. pectiniforme.

1. Lima (Plagiostoma) duplicata Sow. sp. Zoudakar Bb—1 ex.
2. Lima (Plagiostoma) aff. semicircularis Gldf. Zoudakar Bb—1 ex.

Resembles Lima Phillipsi d’Orb. in its general form and the species of Goldfuss in the ribs, which are not so fine as those of Lima Phillipsi.

1. Lima (Limatula) subhelvetica n. sp. Zoudakar Bb—3 ex. (pl. II, fig. 18—19).

Form somewhat oblique, rather broad and swollen; the middle of the valve is ornamented with rather fine ribs, divided by broader intervals; in these intervals one sees ribs of the second order and ribs of the third order, always finer; the anterior and upper part of the valve is ornamented with very fine and finally indistinct ribs; these ribs are as if compressed by a force directed toward the middle of the valve.

This species resembles Lima helvetica Opp. (see Morris and Lycett; Great Oolite Mollusca; supplement; p. 41; pl. XXXIII, fig. 8), but

it is distinguished from it by its larger dimensions, by its more numerous intermediate ribs, and by its rarer principal ribs.

1. Hinnites cf. abjectus Phill. sp. Zoudakar Ac—1 ex.

2. Pecten (Chlamys) fibrosus Sow. Zoudakar Bb—13 ex.; Gunib No. 1—2 ex.; Zoudakar Ca—1 ex.

3. Pecten (Chlamys) subinaequicostatus n. sp. Zoudakar Bb—25 ex. pl. II, fig. 20—21).

Almost round in form; the left valve is not as convex as the right valve; the auricles are almost equal; the sculpture of the right valve is composed of nearly 10 broad, rounded radial ribs with narrower intervals; very fine and close growth lines cross both the ribs and their intervals; on the auricles the ribs are very fine and vertical; the left valve is ornamented by ribs of the same kind, but these ribs and their intervals bear sharp concentric folds; sometimes the folds of neighboring ribs do not correspond; the ribs on the auricles are coarser than those of the right valve.

Pecten inaequicostatus Phill. (Geology of Yorkshire; 2 ed; pl. 4, fig. 11) has thicker and less numerous radial ribs. Pecten inaequicostatus Lahusen (Rjazan; p. 32; pl. XXXIII, fig. 1) is, apparently, identical with my species. Pecten fibrosus Sow. has finer ribs and wider intervals between them. Pecten vagans Sow. (Mineral Conchology VI; p. 82; pl. 543) resembles the left valve of my species, but the right valves are, it appears, very different.

1. Pecten (Chlamys) fibrosodichotomus n. sp. Zoudakar Bb—2 ex.; Gunib No. 1—1 ex. (pl. II, fig. 22).

Very close to the preceding species; I know only the right valve; the ribs, similar to those of the preceding species in their form, are grouped in twos and unite in twos near the beak; the median interval is deeper and broader than the others; this species is a little more convex than the preceding one.

1. Pecten (Entolium) demissus Bean. Zoudakar Bb—6 ex.; Gunib No. 1—1 ex.

2. Pecten sp. Zoudakar Bb—1 ex.

A fragment of a flat shell, the surface of which is ornamented by indistinct radial sculpture; it recalls some poorly known species of Pecten from the Russian Upper Jurassic.

1. Trigonia sp. Gunib No. 1—1 ex.

An indeterminable mold.

1. Exogyra sp. ind.—Gounib. No. 1—2 ex.

In its general form it recalls Exog. reniformis Gldf. (Petrefacta Germaniae II; p. 34; pl. LXXXVI, fig. 6—7) but is larger.

1. Gryphaea sp. Zoudakar Bb—1 ex.

May be a small specimen of Gr. dilatata Sow. (Mineral Conchology II; p. 113; pl. 149).

1. Gryphaea Zudacharica n. sp. Zoudakar Bb,—2 (3) ex. (pl. II fig. 23).

I know only the left valve; it is free in the adult and attached by a small pit in the young; its form is almost hemispherical; the surface shows only irregular growth marks; one (third) small specimen, which I refer here with some hesitation, resembles Ostrea calceola Zieth. (see Benecke: Die Eisenerzformation von Elsass-Lothringen; p. 156; pl. XII, fig. 3—10).

This species recalls the more inflated varieties of Gryphaea dilatata Sow.; but the indistinct beak distinguishes my form from Sowerby’s species.

1. Ostrea sp. Zoudakar Ac.—2 ex.

Fragments of large indeterminable oysters.

1. Ostrea sp. Zoudakar Bb—1 ex.

An indeterminable mold.

1. Oxytoma inaequivalve Sow. sp. Zoudakar Bb—2 ex.

I include with it Oxytoma Münsteri Gldf. sp.

1. Inoceramus cf. cordati Uhl. sp. Zoudakar Bb—1 ex.

2. Gervillia aviculoides Sow. sp. Zoudakar Bb—7 ex.; Gounib No. 1—2 ex.; Zoudakar Ca—1 ex.

3. Pinna sp. Zoudakar Bb—1 ex.

4. Cucullaea cf. subcancellata Borissiak. Zoudakar Ab—1 ex.

5. Waldheimia umbonella Lam. sp. Zoudakar Bb—1 ex.

6. Terebratula sphaeroidalis Dav. mut. Balinensis Neum. Zoudakar. Bb—1 ex.

7. Terebratula maxillata Sow. Zoudakar Bb—1 ex.

8. Terebratula bissufarcinata Schl. sp. Zoudakar Cc—5 ex.; Zoudakar Da—2 ex.

9. Terebratula subsella Leym. Zoudakar Da—12 ex.; Zoudakar Db—1 ex.

10. Rhynchonella moravica Uhl. Zoudakar Cc—4 ex.

11. Rhynchonella cf. inconstans Sow. sp. Gounib, Upper Jurassic—1 ex.

1. Rhynchonella varians Schl. sp. Zoudakar Bb—55 specimens; Gounib Nos. 1–3 specimens; Zoudakar Ca—1 specimen.

2. Rhynchonella concinna Sow. sp. Zoudakar Ac—1 specimen.

3. Serpula gordialis Schl. sp. Zoudakar Ac—about 10 specimens.

4. Collyrites elliptica Desm. Zoudakar Bb. 5 specimens.

5. Cidaris sp. Zoudakar Db—1 specimen.
   A fragment of a spine.

6. Eugeniacrinus sp. Zoudakar Ac.
   Several fragments of stems.

7. Cyathophora Bourgueti Defr. sp. Gounib; probably Upper Jurassic.

8. Cyathophora Stuckembergi n. sp. Gounib; probably Upper Jurassic (pl. II, fig. 24).

The diameter of the calyx—2.5 mm; the distance between calyces—1 mm; 3 cycles of septa; 24 ribs on the outer surface of a calyx; the ribs of neighboring calyces are sometimes confluent.

It is distinguished from the preceding species by its smaller calyces.

Conclusion.

Of the 102 species described and named in this article, 66 were collected in the Bb limestone of Zoudakar; it is the fauna of this limestone that must serve as a basis for determining the age. Of the 66 species of this limestone, 24 are new or indeterminate species; of the remaining 42 species, 33 are Callovian species. Nine species are Oxfordian, or Bathonian or Bajocian; of these 9 species, 5 can be determined only as aff. or cf.; the 4 are of little characteristic value from the stratigraphic point of view (Modiola plicata Sow., Terebratula maxillata Sow., Goniomya sulcata Ag., Terebratula sphaeroidalis Dav. mut. Balinensis). Consequently, the Bb limestone must be assigned to the Callovian. Eighteen ammonites of this limestone are either from the Middle Callovian or do not prevent assigning this age to the Bb limestone.

Consequently, the Middle Callovian is a probable age for the Bb limestone. This probability is changed into certainty by the stratigraphic data. The Bb limestone at Zoudakar supports the greenish limestone Ca; at Gounib, in this limestone, I collected 19 species; of these species Peltoceras athleta is a form characteristic of the Upper Callovian; Cosmoceras Gulielmi, Perisphinctes Comptoni and Rossicus were found in the Middle Callovian; consequently the Ca limestone can be only the base of the Upper Callovian: the Bb limestone is suppor-

... by the yellowish marly and sandy limestone Ac with 13 species; of these species Macrocephalites macrocephalus is characteristic of the Lower Callovian, and Cosm. macrocephali is a new species very close to Cosm. Jason; one should unite Cosm. macrocephali and Jason if one wished to understand Cosm. Jason as vaguely as Mr. Nikitin does (he unites Cosm. Jason and Cosm. subnodatum Teiss); consequently Cosm. macrocephali is a type indicating rather the Middle Callovian, and the limestone Ac must be assigned to the upper part of the Lower Callovian. Consequently the stratigraphic position of the limestone Bb is that of the Middle Callovian. Of the same age are probably Astarte undata Gldf. sp. from an unknown locality near Gunib, Erymnoceras Renardi Nik. sp. and Perisphinctes indicus Siem. from the Kadjal-Maka—Zoudakar road. Perisphinctes subtilis Neum. from an unknown locality near Gunib is probably from the Lower Callovian. For determining the precise age of the lower beds of Zoudakar (Aa and Ab), I do not have sufficient faunal data. The age of the upper limestones, such as bed Ca of Zoudakar, is Upper Jurassic, but the faunal data are insufficient, and I can only indicate conjecturally the age of the separate beds. The limestones Cb and Cc are probably Oxfordian; the limestone Da—Kimmeridgian, the limestone Db—Kimmeridgian or Tithonian. I do not attach much importance to these determinations, based on insufficient faunal data.

The Callovian limestones Ac, Bb, and Ca, in their petrographic characters (impure marly limestones; in part sandy), in their stratigraphic position (at the base of the Upper Jurassic limestones), and in their fauna, are identical with the impure limestones at the base of the “upper stage” of Abich and Uhlig. Of the 27 species assigned to this level by Uhlig, only 7 species are absent from my material, and the most frequent species are identical. Consequently the impure limestones of Abich and my Callovian limestones are one and the same, and the “level extending across Daghestan” of Abich is the Callovian. The age of this level was determined correctly by Sjögren, but this determination was neglected by more recent investigators.

The section of Reuz is not applicable to the part of Daghestan visited by me; the determinations of this geologist contain a few questionable points; cited as Callovian species, Stephanoceras coronatum, Hecticoceras lunula and hecticum are not fixed stratigraphically and are found with Bajocian and Bathonian forms. Bog-

danowitsch¹ cites Hecticoceras lunula and punctatum with Lioceras concavum—a Bajocian species—and found this latter species in a higher bed.

Compelled to finish my work more quickly than I would wish, I set out only very briefly a few general conclusions at which I have arrived.

The Callovian fauna of the part of Daghestan visited by me is that of middle Europe and central Russia. Mediterranean elements are almost absent. This result is in contradiction with the Mediterranean character of the Callovian fauna of the Central Caucasus. It seems to me that this contradiction is only apparent. The characterization of the Jurassic provinces given by Neumayr is in need of revision and contains provincial and facies characters that have not been properly distinguished.

The facies of the Callovian fauna described is quite characteristic. The abundance of the so-called “myacites” (Pholadomya, Ceromya, Gresslya, etc.), of Pecten of the fibrosus group, and Rhynchonella varians are the characteristic features. The ammonite species are rather numerous, but almost every species is represented by only a single specimen. Belemnites are rare. A similar facies is little known in the Callovian but very widespread in lower and higher horizons. This gives part of the fauna described an illusory appearance of the Upper or Middle Jurassic. It is for this reason that I explain Uhlig’s inaccurate determination of the age of this fauna.

The finds of Upper Jurassic ammonites in Daghestan (Perisphinctes plicatilis by Uhlig, Virgatites dorsoplanus by Reuz) have not been fixed stratigraphically, and their significance is not yet clear. All this is a matter for future investigations.

Plate I.

1a 2b 2a

1b 3a 3b

4b 4a

5a 5b

Phot. P. Pavlova

Explanation of the Plates.

Plate I.

Fig. 1. a—b. Cosmoceras subornatum n. sp. Gounib No. 1.

Fig. 2. a—b. Cosmoceras Zoudakharicum n. sp. Zoudakar Bb.

Fig. 3. a—b. Cosmoceras Daghestanicum n. sp. Zoudakar Bb.

Fig. 4. a—b. Cosmoceras macrocephali n. sp. Zoudakar Ac.

Fig. 5. a—b. Pronoëlla Calloviensis n. sp. Zoudakar Bb.

Plate II.

Phot. P. Pavlov.

Plate II.

Fig. 6. Arcomya Caucasica n. sp. Zoudakar Bb.

Fig. 7. a—b. Arcomya inaequivalvis n. sp. Zoudakar Bb.

Fig. 8. Arcomya dubia n. sp. Zoudakar Bb.

Fig. 9. Arcomya cf. inflata Terqu. et Jourd. Zoudakar Bb.

Fig. 10. Pholadomya exaltata Ag. Zoudakar Bb.

Fig. 11. a—b. Pholadomya subexaltata n. sp. Zoudakar Bb.

Fig. 12. Pholadomya subcanaliculata n. sp. Zoudakar Bb.

Fig. 13. Pholadomya rugosa n. sp. Zoudakar Bb.

Plate III.

16

17

14

19

15

20

21

18

24

22

23

Phot. P. Pavlov.

Plate III.

Fig. 14. Pholadomya rugosa n. sp. Tsudakhar Bb.

Fig. 15. Gresslya trigonalis n. sp. Tsudakhar Bb.

Fig. 16. Ceromya Calloviensis n. sp. Tsudakhar Bb.

Fig. 17. Ceromya Calloviensis n. sp. Tsudakhar Bb.

Fig. 18. Lima (Limatula) subhelvetica n. sp. Tsudakhar Bb.

Fig. 19. Lima (Limatula) subhelvetica n. sp. Tsudakhar Bb.

Fig. 20. Pecten (Chlamys) subinaequicostatus n. sp. Right valve. Tsudakhar Bb.

Fig. 21. Pecten (Chlamys) subinaequicostatus n. sp. Left valve. Tsudakhar Bb.

Fig. 22. Pecten (Chlamys) fibrosodichotomus n. sp. Right valve. Tsudakhar Bb.

Fig. 23. Gryphaea Zudacharica n. sp. Left valve. Tsudakhar Bb.

Fig. 24. Cyathophora Stuckenbergі n. sp. Gunib. Collection of Prof. Stuckenberg.

1. “Das Dibrar System im südöstlichen Kaukasus,” Mémoires du Comité Géologique, nouvelle série, livr. 26, pp. 132–133. ↩↩