GENUS ZALOPHUS. 275 



GENUS ZALOPHUS, Gill 



Arctoceplialus (in part), GRAY, Cat. Seals and Whales, 1866, 55. 



Zalophus, GILL, Proc. Essex Institute, July, 1866, v, 7, 11. Type Otaria 



gillespil, McBain. 

 NeopJioca, GRAY, Ann. and Mag. Nat. Hist., 3d series, 1866, xviii, 231 



Type Arctocephalus lobatus, Gray. 



Molars -E| ? large, closely approximated, the last under the 

 hinder edge of the zygomatic process of the maxillary. Muz- 

 zle narrow. Superior profile, from the postorbital process ante- 

 riorly, gently declined. Bony palate moderately contracted 

 posteriorly, and but slightly depressed. Hinder edge of the 

 palatals deeply concave. Pterygoid hooks slender. Posterior 

 nares broader than high 5 anterior higher than broad. Post- 

 orbital cylinder narrow and elongate. The postorbital con- 

 striction of the skull is deep and abrupt, giving a quadrate or 

 subquadrate form to the brain-box, which varies to triangular 

 through the varying degree of prominence of its latero-anterior 

 angles. The postorbital processes are triangular, developed 

 latero-posteriorly into a rather slender point. The sagittal 

 crest, in very old males, forms a remarkably high, thin, bony 

 plate, unparalleled in its great development in any other genus 

 of the family. The general form of the skull is rather narrow, 

 much more so than in Eumetopias, and nearly as much so as in 

 Arctoceplialus, the breadth to length being as 60 to 100. 



Zalophus, so far as the skull is concerned, is the most distinct 

 generic form of the family, it being thoroughly unlike all the 

 others. In general form, as in size, it more nearly resembles 

 Arctoceplialus than any other genus, but differs from it in the 

 dental formula, as well as in its enormously produced crests. 

 It differs from Otaria in having one pair less of upper molars, 

 in the slight depression of the bony palate, the less extension 

 posteriorly of the palatines, the much narrower muzzle, the 

 much less abrupt declination of the facial profile, its much 

 higher sagittal and occipital crest, and in its narrower and 

 more elongated form. 



It differs from Eumetopias, as already pointed out, in having 

 all the upper molars closely approximated, in the greatly con- 

 cave outline of the posterior border of the palatines, and other- 

 wise much as it differs from Otaria. 



Zaloplms differs from Callorliinus in its smaller number of 

 upper molars, its high crests, narrower and more elongated 

 muzzle, and in the more declined profile of the face. In the 



