186 Mr Neill on the Beavers of Scotland. 
same parts in the recent specimens. The difference, however, 
as far as can be ascertained from a comparison of the bones of the 
head, cannot be considered as more than sufficient to constitute a 
variety; not being more important than what occurs in varieties in 
the vegetable kingdom, in which, when the same species of plant 
happens to be a native of both hemispheres, the eye can at once 
discern a difference of habit, although often so slightly charac- 
terised as to render it difficult to express it in words. 
Both the fossil heads appear to have belonged to full grown 
animals. This opinion rests on two grounds : 1. On a compari- 
son, 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, 2. On the 
state of the sutures and ridges of the cranium. In the Perth- 
shire specimen, the squamous sutures of the parietal bones 
are partly obliterated ; and in the Berwickshire specimen, al- 
though these sutures are distinct, yet the crest or ridge between 
the tvio temporal muscles, in the course of the sagittal suture, is 
considerably raised ; and in the Hudson’s Bay skulls, both these 
characters are known equally to indicate the adult or perfect state. 
Neither of the fossil skulls, however, had belonged to old ani- 
mals ; for, in a Canadian specimen in Hr Barclay’s collection, not 
only are several of the sutures nearly obliterated, but the com- 
ponent pieces of the cuneiform bone, and the cuneiform process 
of the occipital bone, are united ; while in both the fossil spe- 
cimens, these divisions remain evident ; circumstances which sa- 
tisfactorily show that this Canadian specimen had been older than 
any of the others, although it is certainly not of larger dimensions. 
The Scottish specimens, it may be- remarked, seem very 
much to agree with a fossil beaver’s head described and figured 
by M. Cuvier, in his eiabor.ate Recherches sur les Ossemens 
fossiles de Quadruples,” voL iv. sect. Be rongeurs fossiles. 
This specimen was found by M. Traulle, in the course of dig- 
ging a peat-moss in the Valley of the Somme in Picardy ; and 
the same peat-moss afforded, as with us, large horns of deer. 
M. Cuvier mentions, that he possesses skulls of the adult 
Canadian beaver, but that he has not been able to procure the 
skull of the adult European beaver, to compare with them. It 
may be remarked, that this writer must, by the term adultef 
