88 THE VOYAGE OF H.M.S. CHALLENGER. 



both in this and in other genera. Only five upper post-canines are figured by Peters in 

 his specimen of Arctocephalus philippii, the 5th being in line with the posterior border 

 of the maxillary root of the zygoma ; iu Arctocephalus argentatus, however, six upper 

 post-canines are represented ; possibly the absence of a sixth upper post-canine in Peters' 

 specimen of Arctocephalus philippii may be an individual peculiarity. In the British 

 Museum is a skull marked Arctocephalus nigrescens from Juan Fernandez, and presented 

 by the Government of Chili, which in its general appearance resembles my specimens of 

 Arctocephalus australis, and it also has six upper post-canines. The under surface 

 of the tympanic is however smoother, and the lower border of the mandible runs almost 

 straight from symphysis to subcondyloid process. The young Fur-Seal described on 

 p. 52 of this Eeport was the pup of the Fur-Seal of Juan Fernandez, but its immature 

 condition prevents me from saying definitely whether it was Arctocephalus australis 

 or another species. 



