162 
stratigraphical division for the Russian Palaeocene beds, correspon- 
ding exactly to the division of these beds in Western Europe. But 
Arhangelski,') several years later, after a thorough revision of the 
earlier, and study of the new collections, finds it almost impossible, 
owing to the unusual mixture of the Montian and the Thanetian 
forms in the upper Sysran and Saratov Series. It is doubtiul, he 
says, whether Montian forms persisted there during the Thanetian, 
or whether some of the Thanetian had already appeared in the Mon- 
tian. He concludes that general conditions must have been different 
in the two regions. A still better example we find in the Middle 
and Upper Eocene Molluscan faunas, about which N. Sokolov*) 
says, „lt is not of small importance that the Oligocen 
forms appear, and it proves that certain species, which 
in Western Europe are considered as being of the Oli- 
gocene age, had existed during the Eocene in South 
Russia“. 
In the Aral Sea Tertiary fauna the following are the Eocene 
species, or more or less allied to them: 
\x*) Aspidopholas sp. aff. affinis Desh. 
x Panopea intermedia Sow. 
0*) Solen cf. vaginalis Desh. 
Corbula (Cuneocorbula) sp. aff. angulata Lam. 
Meretrix (Pitaria) sp. aff. sulcataria Desh. 
Meretrix (Pitaria) cf. transversa Sow. 
Meretrix (Pitaria) sp. aff. ambigua Desh. 
Meaetrix (Calpitaria) sp. aff. M. (Callista) proxima Desh. 
Ostrea plicata Sol. var. 
Ostrea pera Trauts. aff. O. cymbula Lam. 
Dentalium (Entaliopsis) cf. striatum Sow. 
Dentalium Trautscholdi v. Koenen aff. D. grande Desh. 
Dentalium (Fustiaria) cf. fisura Lam. 
Calytrea aperta Sol. 
Calypetra cf. obliqua Sow. 
Turritella sulcifera Desh. var. 
Turritella angulata Sow. 
Mesalia fasciata Lam. 
Mesalia Herberti Desh. 
Vermetus Bognoriensis Mantell. (? var.) 
Aporrhais Sowerbi Mantell. 
Rostellaria (Hippocrene) ampla Sol. (? var.) 
Cassidea ambigua Sol. var. 
Eutritonium (Sassia) expansum Sow. 
Tritonidea sp. aff. Morrisi Edw. 
Sycum bulbus Sol. 
Sycum pyrum Sol. 
Pi 
OOR KH MOXOOO RN XS OO O9 00 
< 
en 
O 
POPA ODO 
') Arhangelski: Le progrčs des etudes des depots palaeocenes en 
Russie a partir de 1905 jusqu’en 1911. Ann Geol. et Miner. de la Russie vol. XIV. | 
') N.Sokolov: Die untertertiaren Ablagerungen Südrusslands. Mem. Com 
Geol. IX, 2, (1893) p. 287 (German text). 
%) x indicates the presente of the species in the lower horizon. 
') o in the upper horizon. 
