198 
\ 
For the determination of the species I was in a position to 
consult the complete literature concerning this fauna (cited in foot- 
notes) and also allowed to use for comparison the specimens in 
rich collections of Englisch and foreign Eocene and Oligocene Mol- 
lusca. in the Sedwick Museum, Cambridge, and in the British Mu- 
seum, Natural History Departement. I must say here that a close 
comparison of the Aral Sea specimens with those of the Budzak, 
Kiev, and Harkov Series of South Russia would be most desirable, 
but I was not in a position to do this, since such collections, so 
far as I was able to trace, do not exist in England. 
že 
* ” 
The Lower Tertiary Mollusca from the N. and N. W. shore of 
the Aral Sea were first described by Abich.!) who regarded them 
as of the age of the Middle Eocene („Parisian“). About a year later 
Trautschold*) published the results of his study of another small 
collection of fossils, containing practically the same species as that 
examined by Abich, and he regarded them as being of the Middle 
and Upper Eocene Age. Von Koenen?) several years later, refer- 
ring to the works of Abich and Trautschold, expressed a doubt as 
to the Eocene age of the fossils. and sug ggested that they might be 
of the Lover Oligocene Age. Later on he had lent to him for revi- 
sion the fossils previously examined by Trautschold, and he found 
that he was right in his doubts and definiteky proposed the Lower 
Oligocene age for them.*) The fossils in this collection were obtained 
from two lithgically distinct horizons, viz. (1) sands and sandy clays 
and (2) gray limestone, but in V. Koenen’s opinion, so far as their 
age is concerned, they show no difference whateer. 
‘After this revision no palaeontological study of this fauna ap- 
peard till 1912, when a paper „On some new or uncommon shells 
from the Tertiary beds of the northern schore of the Aral Sea“, by 
P. Mihailovski*) was publisched*by somme friends of his, for he 
died before he was able to complete his work. This is only a short, 
preliminary study of the fossils collected at the Termenbes (a hill 
and a village between the Aral Sea an Lake Chalkar) and at Sak- 
saulska (a railway stktion not far from the Teemenbes). It contains 
some notes relating to the species described in the earlier works, 
with brief descriptions (often without figures) of some. additional 
species. He is of the opinion that the fauna is composed of botlı 
Eocene and L. Oligocene species, and that it is hardly possible to 
determine without a closer study of different layers whether we have 
') Abich: Beiträge zur Palaeontologie der Asiat. Russlands. Mem. Acad 
Sc. St. Peterspurg 6 ser. 7. 1858. 
') Trautschold: Über Petrefakten vom Aralsee. Bull. Soc. Imper. Natur. 
Moscow 1859. 
>) V. Koenen: Zeitschr. d. d. geol. Gesellsch. XVII. 1865. S. 447. 
') V. Koenen: Unter-Oligocine Tertiar Fauna von Aralsee. Bull. Soc 
Imper. Natur. de Moskow. 1868. S. 1 
5) Mihailovski: „O wbKOTOpbIXxB HOBLIX MAN PbAKURB PAKOBNRAXG MBB TPe- 
IINBIXB oraomeniir Chrepnoro moGepexmwa Apaaseraro Mopa*. Sitzungsb. d. Natur- 
forschergesellschaft bei d. Univ. Dorpat. Bd. XXI. Lif. 1—2. (1012) p. 120 (in 
Russian). 
