Mammalia. 31 



claws, tlie liiud-ilippers may show some variation, as this species 

 is not, like Leptonychotcs and Oriiiiiatoplioca, one of those to which 

 attention has been directed as lacking hind claws on its hind- 

 flippers. 



As regards the sexes Mr. Bruce makes the interesting and 

 unexpected statement that " Dr. Donald also noted that the females 

 of the larger species were larger than the males " — a statement to 

 which I would draw the attention of future explorers as well worthy 

 of confirmation. 



Skull. 



The tabular record given below corresponds to that given in the 

 case of Leptoiiijchotcs. 



Distinguishing characteristics. — The skull of the Leopard-Seal 

 needs no description. It is well known, and lias been described by 

 Owen in the Catalogue of the Osteological Museum of the Eoyal 

 College of Surgeons of London (see Nos. 3938 to 3941). It is at 

 once distinguishable by two characters from the skull of any other 

 living Seal. These characters are — (1) the great length and size of 

 the skull, and (2) the powerful teeth which are recognisable at all 

 ages by their large proportions, and the peculiar arrangement of the 

 cusps. Of these there are three, placed one after the other in a line 

 running parallel to the long axis of the jaw. The apices of the 

 two smaller and outer cusps usually incline towards the larger 

 central cusp, which itself bears a recurved apex. In addition, it 

 should be noticed that in no Seal of the Antarctic are the 

 lambdoid and sagittal crests so prominently developed as in this 

 species. 



Sex. — The young male brought home by the Belgian Expedition 

 is the only one of which the sex has been definitely ascertained. 

 This is regrettable, since very considerable differences of size and 

 proportions occur amongst the skulls of this species. I had supposed 

 that these must represent sexual characters, and I further believed 

 that the larger specimens with stronger canines, enormous develop- 

 ment of the lambdoid, and, in some cases, of the sagittal crests, would 

 prove to be males. Quite upsetting this supposition is the observa- 

 tion of Dr. Donald, as reported by Mr. Bruce, that in this species the 

 females are larger than the males — a statement which, if not based 

 upon some error, is of considerable interest, since it is, so far as I 

 am aware, not applicable to any other species of the Pinni- 

 yedia. At all events, until the point be finally settled by further 



