348 THE ZOOLOGIST. 



I have given the descriptions of the two species alternately, 

 so that the various plumages may be more readily compared. 



Any ornithologist looking at the series of A. gambeli when 

 they are placed side by side in a row, with their breasts all 

 forward, could never doubt that they all belonged to one and the 

 same species, judging by plumage alone. Upon scrutinising the 

 series of A. albifrons under similar conditions, it is also equally 

 clear that they belong to one and the same species, and that 

 those species are distinct and easily separable. Turn all the 

 birds round and examine the outlines of the bills, and the 

 difference will be seen to be very striking. When one's eyes 

 become thoroughly accustomed to these outlines, it is perfectly 

 easy to separate the species by bills alone. 



I now come to a very important point. I have said that I 

 have discovered a further valuable osteological distinction : it is 

 that the neck in A. gambeli is about lj in. longer than in 

 A. albifrons. 



Up to January last I had secured all my specimens singly, 

 and had not noticed the difference in the length of neck ; but in 

 that month I was fortunate enough to get two specimens at one 

 time — an immature gambeli and adult albifrons, and when the 

 two birds were lying before me I was instantly struck by the 

 extraordinary difference in the lengths of their necks. After 

 skinning the birds and dislocating the necks at the base of the 

 skull, the measurements were : — Adult albifrons 7j in., and 

 immature gainbeli 9 in. I should not have attached too much 

 importance to this single instance, but I was enabled during 

 February to abundantly corroborate this evidence by getting two 

 adult gambeli which gave me necks of 8| in.* and 9 in. ; also 

 another adult albifrons with a neck 1\ in. 



I think, in the foregoing remarks, I have given abundance of 

 proof in differences of plumage and osteological characters already 

 well known to fully establish the distinctions between the two 

 birds ; but the final discovery ought surely to be all that is 

 required to prove the specific validity of Anser gambeli. 



It will perhaps be useful to give here, in tabular form for 

 easy comparison, the measurements and weights of the various 

 specimens : — 



::: Injured by shot. 



