50 SontJiern Cross. 



. Skulls. 



In the specimens brought home by the 'Southern Cross ' the numbers 

 are those used by Mr. Hanson. Of these four, one (No. 1) is the 

 smallest adult, another (No. 2) the largest known, the latter exceeding 

 slightly in size No. 897 of the ' Belgica ' collection, which considerably 

 exceeds the largest of Eoss's own specimens (No. 43, 11, 25, 4). 



DistinguisJiinr/ characteristics. — The skull of Ross's Seal cannot 

 possibly be confounded with that of any other living Pinniped. As 

 regards general appearance, its nearest resemblances lie with Cijsto- 

 Ijhorct cristata, Erxleben, of Arctic waters. In size it aljout equals 

 that of Leptonychotes, and is slightly smaller than that of Lobodon. 

 Here the resemblance ceases : the feeble dentition, broad inter- 

 zygomatic and short naso-palatal regions, together with the vertical 

 inclination of the nares, at once mark its distinctness. 



The cranial characters of Ommatophoca are exceedingly puzzling. 

 Were it not for the differences of dental formulae {Ommatophoca 

 possessing one more incisor on each side of the lower jaw than 

 Cystophora), we should have very strong grounds for including it in 

 the Cystophorinae. Indeed, its resemblances to Cystophora are very 

 remarkable. As pointed out by Sir W. Turner, the two skulls 

 approach each other in the vertical inclination of the anterior nares, 

 in theix relation to the infraorbital foramina, in the great width of 

 the orbits and interzygomatic regions, and in the length of the 

 ascending portions of the premaxillae. These are so short as to 

 leave a definite part of the anterior nares bounded by the superior 

 maxillae. He might have added the feebleness of the post-canine 

 dentition. They differ, however (besides the dental formula), in 

 the greater length of the nasals of Ommatophoca, in which also the 

 superior maxillae articulate with their outer border as far as the tip, 

 and do not leave the anterior part of their border free. Further, the 

 palate plates of the palatal bones are shorter in Ommatophoca — a 

 character evidently connected with the resonant vocal powers of the 

 animal — the upper incisors are immensely more feeble, and the shape 

 of the crowns of the cheek-teeth is quite distinct. 



Most of these characters are peculiar to Ommatophoca and are not 

 found in any other genus, but, in addition to its dental formula, 

 which allies it to the Stcnorhynchinae, it finds a connection with 

 that family through Lohodon, in which genus I find to a lesser degree 

 a similar conformation of the pre-maxillae. 



An account of the teeth will be given below. They do not help 



