359 



differs from the adult one in the form of the hinder opening of the 

 palate, which is very large and gradually contracted to an angle 

 in front of the mouth. I am not aware that the form of this 

 part is changed by the age of the specimen. It may be the case in 

 this species, but it is not so in the only species with which I have 

 the opportunity of comparing it, that is to say, in a series of skulls of 

 diiferent ages from the young to the adult, of a Seal of the allied genus 

 Otaria (O. leonina). 



The Monterey Seal may be the " Lion Marin de la Californie " of 

 Choris, ' Voy. Pittoresque,' t. 11, from which Phoca californiana of 

 Fischer's ' Synopsis Mammalium,' p. 231, the Otaria californiana of 

 Lesson, have been derived ; but the accovmts of the species are so very 

 slight, that there is nothing but the habitat and the name to lead 

 one ; and we already have two very distinct species of Sea Lions — 

 Arctocephaliis monteriensis and A. (/illesjni — from California. 



The skull of the Behring Straits Sea-Bear is so distinct from that 

 of the other species, that I am induced to suggest that it should be 

 regarded as a distinct genus from the Arctocephali of F. Cuvier. 

 The three genera may be thus defined. 



I. Callorhinus. 



The face short, forehead convex, regularly rounded from the end 

 of the nasal bone to the middle of the vertex ; the nasal opening is 

 small ; the palate rather concave, contracted behind, short, nearly 

 reaching the middle of the zygomatic arch. Lower jaw short, thick, 

 flattened, expanded beneath just in front of the condyle. 



1. Callorhinus ursinus. 



Arctocephaliis ursinus, Gray, Proc. Zool. Soc. 1859, pi. 68. p. 108. 



II. Arctocephalus. 



The face rather elongate ; the forehead flattened and nearly 

 horizontal from the nasal bone to the vertex ; the palate rather con- 

 cave, contracted behind, short, not reaching beyond the middle of 

 the zygomatic arch ; the nose aperture large, high ; the lower jaws 

 moderate, with a crest-like ridge behind beneath just in front of the 

 condyle. 



The crest-like process on the hinder part of the under edge of the 

 large jaw differs rather in shape and development in the different spe- 

 cies ; but it nowhere resembles the flat expanded disk found in a 

 similar situation in the lower jaw of the preceding genus. 



In my former paper I divided this subgenus into two sections, 

 separating A. hookeri from the other species ; but I had only young 

 or half-grown specimens of the skulls of this species ; and, since I 

 have obtained the young skull from California, I am induced to be- 

 lieve the slight convexity of the forehead and the slenderness of the 

 lower jaw to be dependent on the age of the specimen, and that most 

 probably the forehead of the adult animal becomes flatter, and the 

 lower jaw stronger, as the animal increases in age. 



