360 



The skulls which we have may be divided, according to the form 

 of the hinder edge of the palate, thus : — 



* The hinder edge of the palate, transversely truncated. 



\. Arctocephalus monteriensis, pi, 72. 



Skull broad. 



California. 



2. Arctocephalus hookeri. 

 Skull narrow, elongate. 

 Falkland Islands and Cape Horn. 



** The hinder edge of the palate slightly arched, hemisphericah 



3. Arctocephalus lobatus. 

 Skull broad. 



Australia (Port Essington). 



4. Arctocephalus nigrescens. 

 Skull broad. 



Falkland Islands ? 



### hinder edge of the palate contracted, ovate, 



5. Arctocephalus gillespii, antea p. 110, pi. 70. 

 The skull elongate, narrow. 



California. 



6. Arctocephalus delalandii, antea p. 107, pi. 69. 

 Skull short and broad. 



Cape of Good Hope. 



#### The palate very short, hind edge contracted, acute, angular, 



7. The young skull from California above noticed. 



The skull of A. hookeri, in the concavity and comparative greater 

 width of the palate behind, and in the form of the hinder palatine 

 opening, most resembles that of the genus Otaria ; but it is very 

 distinct from the skulls of that genus, which may be thus defined. 



III. Otaria. 



Face short, shelving ; the nose aperture large, oblong ; the fore- 

 head flat, shelving from the edge of the nose-bone to the middle of 

 the vertex ; the palate very concave, decurved deeper with age, 

 scarcely contracted behind ; car elongated, extending nearly to the 

 articulation of the lower jaw ; the lower jaw with a crest-like ridge 

 on the inner side of the hinder part, just in front of the condyle. 



There is doubtless a great difference in the development of the 

 skull in the male and female Seals, but unfortunately the sex of 

 the specimens from which the skulls have been derived is not marked. 

 In the only species where I have been able to observe this fact, 



