J 



218 ON THE BEAVERS OF SCOTLAND. 



bones are dyed of a brownish hue, but not nearly 

 so dark as those from Perthshire : the exterior ena- 

 mel above mentioned, which in recent specimens is 

 of a brownish-yellow or dull orange colour, has be* 

 come almost jet black. 



On comparing these fossil heads with recent ones 

 from Hudson's Bay and Canada, in the possession 

 of Professor Jameson and of Dr Barclay, it appears 

 that they all belong to the same species of Castor ; 

 but although there seem to be no sufficient specific 

 distinctions, it may be mentioned, that the two fos- 

 sil specimens have a greater resemblance to each 

 other in general shape and proportions, than to any 

 of four recent specimens with which they have been 

 compared. In the fossil specimens, in particular, 

 the nasal bones are proportionally larger than the 

 same parts in the recent specimens. 



Both the fossil heads appear to have belonged to 

 full grown animals. This opinion rests on two 

 grounds : 1. On a comparison, in regard to general 

 dimensions, with recent specimens from Hudson's 

 Bay, brought home by Mr Auld of Leith, and 

 known to have belonged to full grown beavers ; and* 

 % On the state of the sutures and ridges of the 

 cranium. In the Perthshire specimen, the squa- 

 mous sutures of the parietal bones are partly ob- 

 literated ; and in the Berwickshire specimen, al- 

 though these sutures are distinct, yet the crest or 

 ridge between the two temporal muscles, in the 

 course of the sagittal suture, is considerably raised ; 



