42 



ODOB^ENUS EOSMARUS ATLANTIC WALRUS. 



females.* They agree with the one already described as to 

 small size, the absence of well-developed crests and ridges for 

 muscular attachment, small, slender tusks, and general weak- 

 ness of structure, as compared with male skulls of correspond- 

 ing age.t The closed sutures show that they belonged to aged 

 individuals, but in other respects might be presumed to be skulls 

 of young animals, for which such skulls are doubtless usually 

 mistaken. 



FlG. 2. Odobcenus rosmarus, $ . 



From these data it seems fair to conclude that there are well- 

 marked sexual differences among Walruses, manifested espe- 

 cially in the inferiority of size of the female, in the comparatively 

 weak development of the bones of the skull, the smaller size of 

 the bones of the general skeleton, and in the size and form of 

 the tusks. These differences are, in short, just such as, from 

 analogy, one would naturally expect to exist, and confirm the 



* This I inferred from their small size and light structure, aud was pleased 

 to have my determination confirmed by so competent an authority as Dr. 

 Emil Bessels, who pronounced them to be unquestionably those of females. 

 Dr. Bessels's judgment, it is perhaps needless to say, is based on personal 

 experience while on the Polaris Expedition, during whi>'h he secured and 

 prepared numerous specimens of both sexes, which were lost with the ill-- 

 fated vessel. 



tin the National Museum there is also a female skull of the Pacific "Walrus 

 that presents corresponding differences as compared with male skulls of the 

 same species. 



