2 14 THE OX AND ITS KINDRED 
For many years after it became well known in 
England, the Caucasian bison, in spite of some slight 
differences in colouring, was regarded as inseparable 
from the Lithuanian animal. In 1906 it was, how- 
ever, raised by Mr. C. Greve ^ to the rank of a 
separate subspecies, under the name of Bison bonasus 
caucasiciis. Three years later Dr. Max Hilzheimer,^ 
who based his opinion on certain details in the 
structure of the skull which need not be discussed 
on the present occasion, went a step further than 
this, and came to the conclusion that the Caucasian 
bison, in place of being merely a local race of the 
Lithuanian species, represented a species by itself, 
whose affinities were nearer to the American than 
to the Lithuanian bison ; and he accordingly pro- 
posed that it should be henceforth known as Bison 
caucasicus. 
The American bison is, however, undoubtedly a 
derivative from the primitive bison of Europe, and 
it is therefore only reasonable to expect that as we 
proceed from west to east the European bison would 
approximate in some degree to the American. More- 
over, in the number of its ribs, as well as in its 
general form, appearance, and colour, the Caucasian 
bison is essentially similar to the Lithuanian and 
quite unlike the American species ; and there can 
accordingly be little hesitation in continuing to 
regard it as a local race of the former, which in 
certain skull-characters shows some approximation 
to the latter. On this view, if all the species of 
^ " Der Kaukasische Wisent," Zoologischer Beohachttingen, Frankfort- 
am-Maine, vol. xlvii. p. 269, 1906. 
2 "Wisent und Ur im K. Natuialienkabinett zu Stuttgart," lilitt. A'. 
Natiiralienkabinett zu Stuttgai't, 1909, p. 241. 
