188 CASTORID %. 
details of the structure of the teeth in the upper jaw, 
which Cuvier has figured from the drawing transmitted to 
St. 
as 
him,* and since neither of these anatomists appear to 
have had the opportunity of observing the dental charac- 
ters of the lower jaw, in which they are probably best 
marked. 
Cuvier even affirms that ‘ the teeth, and all the forms of 
the head, bear the characters of a Beaver ;” and proceeds, in 
the first edition of the ‘‘ Ossemens Fossiles,” to say that ‘it 
could not be distinguished from the head of the adult Beaver 
of Canada, if the fossil were not one-fourth larger. How- 
ever, as it is not certain that we possess the skulls of those 
existing Beavers that attain the largest size ; and since the 
Beaver formerly inhabited, and still, perhaps, habits the 
shores of the Euxine ; since, also, nearly all the borders of 
the Sea of Azof are but vast alluvial formations,—I think 
one ought to know precisely the matrix of the skull in 
question before deciding whether it belonged to an extinct 
animal.”-- In the second edition of his great work, Cuvier 
modified his expressions, observing that in the drawing 
of the Siberian fossil the post-orbital process of the frontal 
bone has a somewhat different position from that of the 
Beaver, and that the temporal fossa seems scarcely to 
have exceeded the orbit in length; but he concludes, as in 
the first edition, by affirming that there can be no doubt 
respecting the genus of the animal, and that, until more 
certainty was acquired of its specific distinction, it might be 
provisionally named Castor Trogontherium.; 
The well-marked differences which the English fossils have 
demonstrated, not only in the proportions, but in the form 
* Ossemens Fossiles, 1623, tom. vy. pt. 1. pl. iii. fig. 1] and 12. 
+ Ossem. Fossiles, Ed. 1812, vol. iv. Rongeurs Fossiles, p. 4. 
t Ed. 1823, vol. v. pt. 1. p. 59. 
~ 
