COMPARISON WITH ALLIED SPECIES. 329 



themselves are raucli narrower in the younger specimen , espe- 

 cially anteriorly, and hence have a very different form in the two 

 examples. 



In respect to the teeth, it may be added that the older skull 

 has seven upper molars on one side and six on the other, the 

 normal number being six on each side. I have before me two 

 other skulls in which the molars are -J f, and two others in 

 which they are f f ! The form of the molar teeth, especially 

 of the fangs, differs markedly in the two skulls ; those of the 

 younger having the longitudinal grooves of the fangs of nearly 

 all the teeth almost wholly obsolete, while in the other speci- 

 men the roots of nearly all the molars are more or less strongly 

 .grooved. 



Of the two female skulls one is very aged,* as shown by the 

 closed sutures and the greatly worn and defective teeth. The 

 younger, however, is also quite advanced in years. Differences 

 of a similar character to those seen in the males also occur 

 between these, but they are less marked. 



There are also considerable variations in color. Not only 

 is one of the young females much darker below and about the 

 face than the other, but similar variations are seen in the old 

 females and in the males. , 



COMPARISON WITH ALLIED SPECIES. In cranial characters 

 Callorhinus ursinus, as already noticed, is widely different from 

 any of the species of Arctoceplialus, to which, however, it is 

 most closely allied. While in the latter the facial portion of the 

 skull is narrow and depressed, in C. ursinus it is broad, high, 

 and short. The ascending portion of the intermaxillse is also 

 much broader and shorter, and the whole dental armature 

 is much weaker. In the character of the pelage the Northern 

 and Southern Fur Seals present no marked differences, but in 

 respect to color the latter are much grayer than the former. 

 Another obvious difference consists in the great elongation of 



* Respecting the age of these specimens of Fur Seals, Captain Bryant has 

 responded to my inquiries as follows: "The grown females (the mothers of 

 the pups) were average specimens. The only means I had of determining 

 their age was by the evidences afforded by dissection. These were that 

 the older female had given birth to seven young and the other five, which 

 would make their ages respectively ten and eight years. The two grown 

 males were also selected as average specimens in size and color. Judging 

 from their general appearance and color, I estimated them to be ten years 

 old. The two pups were thirty-five days old, and in that time had doubled 

 their size from birth. They were both females." 



