270 THE ZOOLOGIST. 
from the end of the snout to the stump-like tail, and 3 ft. 8 in. in 
girth, and weighed 98 pounds.* 
Two remarkable animals of the Beaver tribe, but considerably 
larger than those now existing, formerly inhabited Europe and 
North America respectively, T'rrogontherium and Castoroides. 
They are both now extinct, but seem to have been contemporary 
with our Beavers. Their remains have been discovered in peat- 
bogs and lacustrine deposits posterior to the drift. The American 
genus Castoroides was much the larger of the two. It was more 
than twice the size of our Beaver: the length of its skull, for 
instance, was nine inches instead of four, while the European 
Trogontherium was a fifth larger than our Beaver.t 
According to the zoological classification now adopted by 
naturalists, the Beaver is placed in the order Rodentia, sub- 
order Simplicidentata, and belongs to the Sciwromorphe or 
Squirrel section of that suborder, forming the family Castoride, 
genus Castor, of which two species are recognised: the Kuropean 
Beaver, Castor jiber, confined to the temperate regions of Europe 
and Asia from France to the River Amoor; and the American 
Beaver, Castor canadensis, ranging over the whole of North 
America from Labrador to North Mexico. 
Whether these two are really distinct species, or merely 
geographical races, is a question upon which opposite opinions 
have been expressed, Prof. Blasius,{ for example, and Prof. 
Brandt§ stating that they cannot with certainty be separated ; 
while Sir Richard Owen|| and Professor Newton] maintain a 
contrary view. Messrs. Coues and Allen treat them as well- 
marked subspecies.** 
* Darwin, ‘ Naturalist’s Voyage round the World,’ p. 49. 
+ “Extinct species of Castor range back from the Post-pliocene to the 
Upper Miocene in Europe, and to the Newer Pliocene in North America. 
Extinct genera in Europe are Trogonthertwm, Post-pliocene and Pliocene ; 
Chalicomys, Older Pliocene; and Steneofiber, Upper Miocene. In North 
America Castoroides is Post-pliocene, and Paleocastor Upper Miocene. 
The family thus first appears on the same geological horizon in both Europe 
and North America.’”’—Wallace, ‘ Geographical Distribution of Animals,’ 
vol. ii., p. 234. 
| © Siiugethiere Deutschlands,’ p. 407. § Mem. Acad. St. Petersb. vii. p. 43. 
|| ‘ British Fossil Mammals,’ p. 196. 
{1 ‘On the Zoology of Ancient Europe’ (1862), p. 25. 
“= € Monographs N. Amer. Rodentia.’ 4to, 1877, p. 433. 
