CHAPTER V 
THE BEAVER AS A SPECIES 
Castor canadensis and Castor fiber. 
Or the order rodentia the beaver is the second in 
point of size, the only species exceeding it being 
the Capibara (Hydrochoerus capivars) of South 
America. The American and European beaver 
constitute the only living representatives of the 
genus castor, and the difference between the two 
is so very slight as to be scarcely noticeable to any- 
one but a scientist. Externally, except in point of 
size, the two species are practically identical, the 
American being slightly larger, but an examination 
of the skulls shows certain minor differences, chief 
of which is the slightly greater proportional length 
of the nasal bones and narrower skull of the 
European species (Castor fiber). Another less 
noticeable mark of distinction is that the castoreum 
obtained from the European species, especially 
those from Russia, is more valuable and contains a 
greater proportion of castorin resin and albumen. 
In point of age the beaver is evidently an animal of 
great antiquity, not only in its present form but 
the larger and extinct Trogontherium (of Europe) 
and the Castoroides (of America), neither of which. 
