Budzak Series. At any rate in the case of the Aral Sea Tertiary, 
there is another argument against the Lutetian age of the complex, 
ie. it lies in complete conformability over the Nummulitic limestone 
containing, according to Abich,') Nummulites irregularis, which 
is consideret as being one of the zone-fossils for the Middle and Upper 
Lutetian. The lowest limit therefore cannot in any case be placed 
here below the uppermost Lutetian. 
it is much more difficult to determine in a similar way the age 
of the uppermost limit of the complex. For this purpose some useful 
observations can be made in studying the character of the fauna of 
the Harkov Series in South Russia, and its relation to the fauna of 
the Kiev Series. The Harkov Series presents a gradual continuation 
of the Kiev Series in every respect.) The fauna of the Harkov Se- 
ries is generally regarded as being of the Lower Oligocene age.?) 
Although the bulk of the fauna bears the character of the Lower 
Oligocene, and though the resemblance of this fauna to that of the 
Lattorfian of North Germany is beyond question, it does not seem 
for the following reasons, unreasonable to assume that, at least par- 
tly, the Harkov Series may be of the Ludian age: a) The Molluscan 
fauna in South Russia and Western Asia began to assume the Oli- 
gocene character much earlier than in Western and South - Western 
Europe, and yet the fauna of the Harkov Series preserves the Eocene 
character considerably more than does the fauna of the Lattorfian of 
North Germany.*) b) A considerable number of species are not iden- 
tical but only closely allied with those from the Lattorfian. These 
variations, says N. Sokolov,’) are not of specifis value, and he attri- 
butes them to the facial differences and the great distance between 
the two provinces. 
But in certain instances they are considerable, and if they were 
not considered from the above point of view, the varieties could be 
made new species. Also a considerable number of new species are 
more closely allied to the Eocene than to the Lower Oligocene 
forms.) c) The same character can be observed not only in the 
faunas of Mandrikovka and Yekaterinoslav, but also in some other 
plases where the fauna of the Harkov Series is found.') d) A con- 
2) Aralsee I. c. 
2) See N. Sokolov: Die unter-oligocanen Ablagerungen Süd-Russlands I. c. 
3) N. Sokolov: Die unter-oligocene Fauna der Glaukonitsande bei der 
Eisenbahnbrücke von Jekaterinoslav. Mem. Comite Geol. St. Petersburg IX, 
3, 1894. 
+) Idem: Die Mollusken-Fauna von Mandrikovka |. c. 
°) See N. Sokolov: Die untertertiare Ablagerungen 1. c. p. 333. 
%) See the list of new species in N. Sokolov: Die untertertiare Ablage- 
rungen |. c. 
°) In the Neocomian clays of the district of Alatyr, A. P. Pavlov (On 
dikes of Oligocene sandstone in the Neocomian clays of te district of Alatyr, 
in Russia. Geol. ‚Mag. N. S., 4, III, (1896) p. 49) has discovered dykes of Oli- 
gocene sandstone containing the following fossils determined by v. Koenen: 
Voluta suturalis, Astarte aff. Bosqueti, Ostrea aff. flabellula, 
Otrea aff. Bosqueti, Nucula cf. Boweobanki, Natica cf. Hantoni- 
ensis and an Acirsa, „probably a new species allied to A. angusta v. 
Koenen“. 
The fauna from Burgas on the Black Sea coast in Bulgaria, is of the same 
character, Cosmann expressed the opinion that in general characters it re- 
