86 THE VOYAGE OF H.M.S. CHALLENGEK. 



Arctocephalus pusillus, and if my specimen is to be referred to that species it is probably 

 to be regarded as that of a female, for we now know much more definitely than we 

 did a few years ago that the females of the Eared Seals are very much smaller than 

 the males. 



Arctocephalus ursinus (Linnaeus). Fur-Seal of North Pacific. 



Ursus marinus, Steller, Nov. coniru. Acad. Petropol., vol. ii. p. 331, pi. xv., 1751. 



Phoea ursina, Linn., Syst. Nat., ed. x. p. 37, 1758. 



Callorhinus ursinus, Gray, Proc. Zool. Soc. Lond., 1859, p. 359. 



Otaria ursina, Peters, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, May 17, 1866, p. 273, 1867. 



Facial part of skull in front of antorbital process short, relatively broad, and with the 

 nasal bones sloping downwards so as to give an aquiline character to the profile view 

 of the face. Anterior nares almost terminal and nearly vertical. This appearance is so 

 characteristic and peculiar as to have induced Dr. Gray to give it generic value, and to 

 form for this species the genus Callorhinus, with which arrangement Mr. Allen coincides. 

 Tympanic distinctly ridged, one ridge running antero-posteriorly ; mastoid massive. 

 Premaxilla articulating with about one-half of outer border of nasal. Hard palate some- 

 what emarginate, its posterior border well in front of hamular pterygoids, which are 

 distinct and curved outwards. Extreme condylo-premaxillary length of an adult male 

 242 mm., interzygomatic width 141 mm. ; width behind external meatus 129 mm. 

 From front of cranial box to posterior border of base of postorbital process 51 mm. ; 

 from same border to premaxillary tubercle 118 mm. The length-breadth index calculated 

 on the interzygomatic width is 58, and on the width behind the meatus 53. The 6th 

 post-canine is not much smaller than the others, with one large cusp and no secondary 

 cusps, usually single-fanged, and well behind the maxillary root of the zygoma. The 

 mandible has no definite angle, and the subcondyloid process is massive and strongly 

 inflected. 



I may refer to Mr. Elliott's work on Alaska for the most complete account of the 

 appearance and habits of this Seal which has yet been published. Mr. Allen has stated 

 that in the character of the pelage this Seal differs in no marked way from the Fur-Seal of 

 the South Pacific, Arctocephalus australis, though the latter is much greyer than the 

 former ; but in Arctocephalus ursinus the toe-flaps of the pes are greatly developed, 

 their extension beyond the digits being nearly equal to the length of the rest of the foot, 

 140 mm., whilst, as I have stated, in Arctocephalus australis (p. 40) they did not pass 

 more than 110 mm. beyond the toes. Though the males of the two species are almost 

 equal in size the female of Arctocephalus australis is very much larger than that of 

 Arctocephalus ursinus. 



