On the Cretaceoiis Flora of Kussmn Sakhalin. 17 



arctica are Upper Cretaceous, at least a part of them must be of 

 this age. We must here keep in mind, moreover, that several 

 collectors took specimens from pebbles together with those from 

 exposures, and generally they were not careful enough in disting- 

 uishing tliem, thus introducing strange elements into some floras, 

 as was noticed by Nathokst,^^ who remarked also that the Tertiary 

 flora of Greenland, with P. arctica, is by no means homogeneous, 

 and must be divided into 1) prebasaltic flora with MacClintocUa 

 and some other ancient forms and 2) basaltic without them. The 

 prebasaltic flora is also to be divided into two horizons. The 

 knowledge of the flora contemporaneous with the Inoceramus horizon, 

 which is typically Senonian, gives stronger gi'ound for a critical 

 study of the age of some " Tertiary " floras of Siberia. For 

 instance, the flora, found on the Bureya, a tributary of the Amur 

 river, with Populus arctica abundant, which is Miocene according to 

 Heer,'^ was recently revised by Konstantow^^ and determined as 

 Paloogenc. This author, however, speaks about some horizons of 

 diflerent ages in the observed exposure, without arranging diflerent 

 species according to horizons, in his description of the fossils. 



I have remarked that the flora of Mount Boguchan on 

 the Amur river, with Platanus Eeeri, must be Upper Cretaceous, 

 and probably has connection with the Dinosauria Bed on the 

 opposite side of the river. After studying the contents of the 

 Senonian flora in the Far East, I am now able to confirm my 

 former opinion on account of similarity of the floras of Boguchan 

 and do la Jonquière. May not the floras of Zagayan on the Bureya 

 and of other places on the Amur be much younger than this, that 

 is, probably equivalent to Laramie? I regard the Anadyr flora, 

 collected by Mining Engineer Polevoi'^ as either of the same age 



1) Nathort (1888), p. 52. 2) Heee (1878 b). 3) Konstaxtow (1914). 4) Polevoi 

 (1915). 



