167 
siderable number of the southern (Priabonian) species in the fauna, 
of the Harkov Series, some of wich do not occur in the Kiev Se- 
ries (Ostrea Martinsi, O. flabellulaeformis, Pecten Biaritzensis, Lima 
Trabayensis, Limopsis striata, Spondylus radula, Cardita Boriss- 
jaki etc.). Also the occurence in the Priabonian of some Lower Oli- 
gocene forms the origin of wich cannot be explained. This makes 
it probable that at least for some time the Harkov Sea. was in di- 
rect communication with the Priabonian Sea.') Many facts make it 
probable that the sea invaded N. Germany by the beginning of the 
Oligocene from the South-East rather than from the North,?) and 
considering the character of the fauna of the Harkov series, and 
comparing it with that of the Lattorfian of N. Germany, we can say 
with Boussak and Haug?) that „the stratigraphical continuity is not 
alwais a proof of synchronism, because the same conditions of sedi- 
mentation may be displaced from one point to anothor of the geo- 
synclinal“. Now if the Harkov Series is of the Ludian age, the Kiev 
Series is of the Bartonian age and so the upper horizon of Aral 
Sea Tertiary. After this necessary diversion, we may conclude that 
theLower Tertiary beds between the Aral Sea andLake 
Chalkar have been deposited with no interruption in 
sedimentation, most probably during the Auversian 
and Bartonian. 
One thing which does not concern us directly but which may 
be a useful argument for the above age of the beds is the follo- 
wing. Haug?) reffering to the origin of the Eocene vertebrate faunas, 
says: a) that Artiodactyls which so suddenly appeared in Europe 
by te beginning of the Lutetian and Ludian, are not of American 
origin, and cites Stehlin*) who believes - that they must be of 
Asiatic origin (Sino-Siberian continent); b) that the immigration was 
interrupted yust between these two periods. Stehlin explains this 
by. a possible interruption of communication during this time. To 
realise the value of this as an argument, let us mention that the 
most recent investigations of the Russian geologists“)-shaw that the 
large Lower Eocene Sea in South Russia had by the end of the 
Eonummulitic almost entirely disappeared, or at least was reduced 
to a very small area, ie., exactly at the time when Artiodactyls in- 
vaded Europe. Then this immigration was interrupted exactly at the 
time ween we assume that the Aral Sea beds were deposited. 
minded him of the Bartonian. F. Toula is doubtful about the Mollusca and 
says that only the Nummulite would make one feel certain about its Eocene 
age. Von Koenen (Über die von F. Toula entdeckte unter-oligocane Fauna 
der Mergel von Burgas. Sitzungsb. d. k. Akad. d. Wiss. in Wien Cl. CII (1893) 
p. 181) however finds that the Mollusca are of the Lower Oligocene age and 
resembles very closely those of Yekaterinoslav. 
1) Cf. Oppenheim: Neue Beiträge zur Geologie und Palaeontologie der 
nel Balkanhalbinsel. Zeitsch. d. D. Geol. Gesell: LVXII (1906) p. 260— 
161: etc. 
2) Cf. Haug: Traite p. 1560. 
>) Traite p. 1471. 
*) Haug: Traite p. 1553. 
5) Die Saugethiere des Schweizerischen Eocens, Abhand. schweiz. paleont. 
Gesell. XXX—XXXVI (1903--1910). 
6) See: Arhangelski: Les progres des etudes etc. I. c. 
