THE LEOPARD SEAL 



247 



Reports (1915), where the weights of two males are given — no. XLII, 305 cm., 606 lb. 

 and no. XLV, about 4 cm. longer, 630 lb. The ' Scotia' seals were apparently weighed 

 piecemeal, and for no. XLII only 3 lb. were allowed for loss of blood which seems very 

 little indeed : no details of weights are given with reference to no. XLV. 



DEVELOPMENTAL STAGES OF THE SKULL 



The skull of Hydriirga is remarkable for its length, that of the male being slightly 

 less attenuated than that of the female, though the latter has wider zygomatic arches. 



The female skull also attains to a greater size and more massive development than 

 the male, and in the majority of specimens distinctions are visible which, although 

 they may appear small when represented by measurements, nevertheless produce 

 substantially different forms. In order to facilitate a comparison of the differences 

 between the sexes two series were selected in which the condylo-basal lengths of one sex 

 were matched as closely as possible in the other. There are fifteen of each. 



Table III. Cotidylo-basal lengths of skulls 



In dorsal view the frontal bones are greatly compressed from the point at which they 

 leave the cranium to form the interorbital bar, but they expand once more to join the 

 maxillae; the transition from the cranial to the orbital part is gradual in the male but 

 rather abrupt in the female, and the bar itself is narrower in the latter. The maxillary 

 expansion is wider in the male, but the preorbital region of that sex tapers rather more 

 rapidly, so that the male has a more pointed snout than the female. In ventral aspect the 

 palate of the female is more rounded anteriorly and less wedge-shaped than that of the 

 male, and the walls of the nasopharynx are closer together. These walls are composed 

 of the vertical parts of the palatines and pterygoids, and in life support the soft palate 

 which in the female therefore is narrower than in the male. 



