658 DR. J. E. GRAY ON SEA-BEARS. [May 2 1 , 



Hah. Port Western, N. H. (Quoy) ; Dusky Bay, New Zealand 

 {For st er). 



The skull which Dr. Hector sent from New Zealand is a true Arc- 

 tocephalus, belonging to the section Euotaria of my Supplement to 

 the Catalogue of Seals, and is quite distinct from the specimens of 

 the skulls which the Museum received from Mr. John Macgillivray as 

 coming from North Australia, which form my subgenus Gypsophoca — 

 indeed, so distinct, that I must consider Gypsophoca a distinct genus, 

 more allied to Phocarctos than to Ar otocephalus. 



The study of the skull would reduce the tribe Arctocephalina, as 

 characterized in the ' Supplement to the Catalogue of Seals and 

 Whales' (1871, p. 11), into two divisions, thus: — 



* Grinders, two {fifth and sixth) hinder upper quite behind the 

 hinder edge of the zygomatic arch. 



1. Phocarctos. Skull elongate, front part much longer than 



twice the length of the hinder part of the skull to the con- 

 dyle. Palate very deep, much wider in the middle. Under-fur 

 sparse. 



2. Gypsophoca. Skull broad behind, tapering in front ; the front 



part one third longer from the condyle than from the condyle 

 to the occiput. Palate narrow. Under-fur abundant. 



** Grinders, the hinder one {or sixth) quite behind the hinder edge 

 of the zygomatic arch. 



3. Arctocephalus. Under-fur abundant. 



The first, second, third, and fourth upper grinders have an un- 

 divided root, whereas the fifth in the upper jaw has the root more 

 or less divided, which in the fifth and sixth is well divided ; 

 but the distinctness of the division of the roots of the grinders 

 appears to depend on the growth of the animal. The position 

 of the grinders in the small skulls may be observed before the 

 bones are united together at the sutures. The milk-teeth of 

 the Seals and the Sea-bears are changed very soon after birth, 

 and these animals have a complete series of the permanent teeth 

 when only a few weeks old. The teeth become larger as the jaw 

 grows in size, but they retain their original position with regard to 

 the parts of the bones of the face and the zygomatic arch. 



Their position affords an excellent character for the distinction of 

 the species and division of them into groups. Allen, in his plates of 

 the northern Sea-bear {Callorhinus ursinus), figures the skull and 

 teeth of two adult animals and the skull of one only thirty-five days 

 old — the latter showing the teeth exactly placed as in the figures 

 of the two adult specimens. These skulls also exhibit the varieties 

 that exist in the form of the hinder opening to the nostrils of the 

 same species, the chief difference arising in the more or less imper- 

 fect manner in which the hinder margin of the palate is developed. 



1. The Sea-lions {Otaria) have the palate produced to a line even 



