188 CASTORID^E. 



details of the structure of the teeth in the upper jaw, 

 which Cuvier has figured from the drawing transmitted to 

 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, inhabits 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. 1 ' 1 -f- 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 TrogontJierium.\ 



The well-marked differences which the English fossils have 

 demonstrated, not only in the proportions, but in the form 



* Ossemens Fossiles, 1823, torn. v. pt. 1. pi. iii. fig. 11 and 12. 

 t Ossera. Fossiles, Ed. 1812, vol. iv. Rongeurs Fossiles, p. 4. 

 J Ed. 1823, vol. v. pt. 1. p. 59. 



