328 CALLORHINUS URSINUS NORTHERN FUR SEAL. 



The limbs are also relatively much larger than in the adult, as 

 mentioned by Quoy and Gaiinard in respect to the Arctocephalus 

 cinereus of Australia,* which enables them to move on land with 

 greater facility than the adult, as the above-mentioned authors 

 have stated to be the case in the Australian species. 



It is not true, however, that the young of C. ursinus are devoid 

 of under-fur, as some writers have affirmed.t 



INDIVIDUAL VARIATION. The two males were both not only 

 full-grown, but quite advanced in age, though in all probability 

 the crests of even the older skull (No. 2922) would have been still 

 further developed. The other male (No. 2923) was somewhat 

 younger, but already had the sagittal crest considerably pro- 

 duced; the teeth, however, were but moderately worn, the mid- 

 dle upper incisors still retaining the groove dividing the surface 

 of the crowns. In the younger male skull the posterior outline 

 of the palatines is but slightly concave, whereas in the other it 

 is deeply and abruptly emarginate in the middle, as deeply so 

 as in the young (one month old) skulls; showing that differ- 

 ences in this respect do not necessarily depend upon differences 

 in age. They also differ in the form of the postorbital pro- 

 cesses, in the younger they having nearly the same form as in 

 Eumetopias, whereas in the older nearly that seen in Zalophus. 

 The postorbital cylinder is also much shorter in the younger, 

 though these two skulls do not present nearly the great differ- 

 ence in this respect exhibited by two very old male skulls of 

 Zalophus already described. Another difference is seen in the 

 parieto-rnaxillary suture. In the younger specimen it is nearly 

 straight and directed forward, the nasals extending consider- 

 ably beyond it. In the other it curves at first moderately back- 

 ward, and then abruptly in the same direction; the rnaxillaries 

 extending in this case slightly beyond the nasals, instead of end- 

 ing considerably in front of the end of the latter. The nasals 



* Voyage de 1' Astrolabe, Zoologie, touie i, p. 89. 



.t It may be added that the young specimens above described had not 

 fully shed their milk teeth. The incisors appear to have been renewed, but 

 both the first and second sets of canines were still present (see Bull. Mus. 

 Comp. Zool., vol. ii, pi. iii, fig. 5), the permanent ones being in front of the 

 others. The three molars of the first set have been replaced by the perma- 

 nent ones, the first and second of which are already quite large. The hinder 

 molars are in one of the specimens but jiist in sight, and doubtless had not 

 cut through the gum. In the other they are a little more advanced. The 

 middle one is quite prominent ; the first is much smaller, while the last or 

 sixth molar is far less advanced than either of the others. 



