20 Art. 8,— A. Kryshtof ovich : 



marine transgression, but at the same time elsewhere, and especial- 

 ly afterwards, sedimentation was going on steadily in continental 

 conditions. 



3. The Ainu an Flora. 



This flora, observed in Erikson's coal-mine on the river Polo- 

 vinka, dififers very much from the succeeding floras of the 

 Gyliakian and Orokkian, as shown in the following list of the 

 Ainuan plants : — 



Gleichenia rig Ida He., 



Gleichenia Zippei Coed a sp., 



Gleichenia sp., 



Asplenium Dicksonianum He., 



Populus cf. p)otomacensis Ward. 

 The characteristic aspect of this flora, quite strange to that of 

 all Gyliakian localities in the neighbourhood, the predominance of 

 ferns, the greater part of which still remains undetermined, and 

 the scarcity of Angiosperms, bring us to the conclusion that this 

 flora is the oldest among the Cretaceous horizons, notwithstanding 

 our incomplete knowledge of the stratigraphy of that part of 

 Russian Sakhalin. Populus shows an afiinity with a form in the 

 Potomac, while the general aspect of the whole flora is allied to 

 that of Kome of Greenland, which may correspond either to Albian 

 only or also to an older system. The contents and distribution of 

 the Ainuan flora will be a most interesting subject for future 

 studies. The following diagram shows the stratigraphie position of 

 our floras in comparison with contemporaneous floras of the 

 Northern Hemisphere. 



