78 THE VOYAGE OF H.M.S. CHALLENGER. 



This specimen is evidently an adult male. The suture between the premaxilla and 

 maxilla has disappeared, though there is an indication that the premaxilla had articulated 

 with about the anterior third of the outer border of the nasal. The basicranial synchon- 

 droses are obliterated. The muzzle is markedly more contracted than in Otaria jubata, 

 and the anterior nares are more oblique in direction than in Arctocephalus. In its 

 general form, however, the skull has many points of resemblance with Arctocephalus. 

 The mastoids are irregular and very prominent. The tympanic bulla is roughened and 

 a strong process projects vertically downwards from it, immediately external to the 

 carotid canal ; this canal opens into the anterior part of the foramen jugulare. 



Palate is neither elongated nor truncated as in Otaria, but slightly emarginate and 

 converging behind last molar ; its posterior border is well in front of the slender hamular 

 pterygoids, and about opposite the middle of the zygomatic arch ; borders of palate 

 scarcely elevated, so that its surface is almost flat, and its widest part is opposite the 

 last post-canine. Posterior border of vomer is concealed by palate, but its superior 

 or sphenoidal articulation is in part seen in the emarginate border of the palate ; 

 vomer not articulating with floor of nose until it reaches vomerine crest of maxilla. 

 Infraorbital foramen opens into floor of orbit distinctly in front of posterior border of 

 zygomatic root of maxilla. Postorbitals triangular, and recurved at the apex. Sagittal 

 crest in the male very high and thin, reaching forwards to the postorbital processes. 



The length-breadth index of this cranium, calculated on the interzygomatic width, is 



57'5, and on the width behind the external meatus is 51 "0. 



5 - 5 



Dentition — post-canines ., relatively large, closely approximated, the most 



o — o 



posterior being below the zygomatic root of the maxilla and in line with or a little 



in front of its posterior border. Mandible with a Quadrilateral subcondyloid process 



much longer than broad, and inflected inwards ; angle marked by a sbght tubercle ; 



lower border of body neither inverted nor everted. Muzzle narrow. The Phocarctos 



elongatus of Dr. Gray is probably this species. 



Eumetopias hookeri (Gray). The Auckland Island Hair-Seal. 



Arctocephalus Hookeri, Gray, Zool. Voy. "Erebus" and "Terror," p. 4, pis. xiv., xv., 1844. 

 Otaria Hookeri, Peters, Monatsber. d. k. preuss. Akad. d.Wiss. Berlin, May 17, 1866, p. 269, 1867. 



Mr. J. W. Clark has definitely established the presence of a large species of Eared 

 Hair-Seal on the Auckland Islands, 1 and an examination of the crania has satisfied him 

 that they correspond exactly with the skulls brought home by Sir J. C. Ross's Antarctic 

 expedition, which Dr. Gray named Arctocephalus hookeri. The skull of this Seal is 



1 Proc. Zool. Soc. Lond., November 18, 1873, with two characteristic figures of the skull, which is also figured in 

 Dr. Gray's Zoology of the Voyage of the " Erebus '' and " Terror," pi. xv. 



