REPORT ON THE SEALS. 00 



Macrorhinus leoninus (Linnaeus). Elephant Seal. Southern and Antarctic Oceans. 



Phoca leonina, Linn., Syst. Nat., ed. x. p. 37, 1758. 



Phoca elephqntina, Molina, Saggio sul Stor. Nat. del Chili, p. 280, 1782. 



Morunga elepltantina, Gray, Zool. Voy. "Erebus" and "Terror," p. 8, pis. ix., x., 1844. 



Macrorhinus anguirostris, Gill, Proc. Essex Inst., vol. v. p. 13, 1866. 



This animal has been described in so much detail in Part I of this Report that it is 

 not necessary for me to repeat its characters here. 



Dr. Gill, Mr. Allen, and other American zoologists have regarded the Californian 

 Sea Elephant as distinct from the southern species, and have named it Macrorhinus 

 anguirostris. Dr. Gill's description 1 was based on the examination of the skull of a female 

 from Lower California, and the name Macrorhinus anguirostris was conferred owing to 

 its narrowed and produced snout, as compared with that of a skull from the South Seas, 

 figured by Dr. Gray in the Zoology of the "Erebus" and "Terror," which was at one time 

 regarded as an adult female, but which is now known to be a male not full grown. If 

 this character of the snout be the only difference between them, and Mr. Allen has stated 

 that the Northern and Southern Sea Elephants differ very little in size, colour, and other 

 external features, it cannot have much if any value as a mark of specific difference, for 

 from my comparison of the male and female crania of the Southern Elephant Seal 

 (Part I.) it will be seen that the male is much broader than the female in the prenasal 

 region, owing to the greater size of the incisor and canine teeth. 



The differences between the skulls of Cystophora cristata and Macrorhinus leoninus 

 are seen to most advantage in the region of the premaxillary bones and anterior nares, 

 in the shape of the tympanic bulla and the relative length of the external auditory 

 meatus, in the position of the orbital orifice of the infraorbital canal, the relative size 

 of the mastoid temporal, the place of articulation of the vomer with the palate bone, and 

 the configuration of the lower jaw. When taken collectively these differences are, I 

 think, sufficient to justify the separation of the genus Macrorhinus from Cystophora. 



Trichechida 



The family Trichechida? contains only a single genus amongst existing mammals, 

 although two fossil genera have been described, Alacthcrium and Trichechoclon. The 

 existing genus is usually called Trichechus, but the old Linnsean term Odobainus has 

 recently been revived for it by some zoologists, and Allen has consequently named the 

 family Odobsenidse. 2 



1 Proc. Essex Inst., vol. v. p. 13, 1866 ; and Proc. Cliieago Acad. Sci., vol. i. p. 33, 1866. 



- I may refer to Mr. Allen's valuable History of the North American Pinnipeds for a full discussion of the question 

 of the generic term which should be given to the Walrus. 



