OSTEOLOGY OF ANTARCTIC SEALS. 



191 



backwards and three-cusped, the central one being longest. In all but the first the 

 post-canines were double-rooted. 



In No. 43 the teeth are not so well developed, and in the upper jaw the left outer 

 incisor and canine are broken. The dentition is not quite easily made out. There is 

 no fifth post-canine, but small sockets are to be observed ; hence we may presume that 

 they were present, having been partly fixed in the natural state by the fleshy gum, a 

 condition pointed out by Weber, Bennet, and Wilson {National Antarctic Expedition : 

 Natural History, vol. ii. p. 46). 



Again, in the lower jaw no central incisor is present, but the two halves of the jaw 

 have been disarticulated. On placing the two halves together, it would seem that no 

 room at all is left for central incisors. A comparison of the measurements of the two 

 lower and upper jaws between outer side of canines shows : — 



No. 2. Upper diameter, 44 mm. 



Lower ,, 30 ,, 

 No. 43. Upper diameter, 48 ,, 



Lower ,, 26 ,, 



In No. 2, which has not been disarticulated, there is a fair amount of fibrous tissue, 

 so it is possible to explain the difference in diameters by the absence of this. Hence, 

 with the fibrous tissue in place in No. 43, room would be made for central incisors. 



Against this may be stated the fact that the upper central incisors are very feeble, 

 and, as the whole of the upper teeth are stronger than the lower, it is possible that the 

 lower central incisors may not have developed. 



Measurements of Skulls. 





Eoss Seal, 



Ross Seal, 



Weddell 



Leopard 





No. 43. 



No. 2. 



Seal. 



Seal. 





mm. 



mm. 



mm. 



mm. 



Extreme eondylo-premaxillary length . 



250 





272 



394 



,, inter-zygomatic width .... 



181 





169 



217 



,, width behind external meatus 



167 





177 



198 



Greatest width of palate ..... 



76 



71 



58 



90 



Width between outer side of base of upper canines 



48 



44 



52 



75 



,, ,, ,, lower canines 



26 



30 



30 



50 



Length of palate in line of suture to central incisor 



81 



82 



105 



157 



Height of skull — basion to mid-occipital crest 



83 





84 



110 



Smallest interfrontal diameter .... 



45 



49 



30 



45 



Length of nasals ....... 



79 



55 



61 



103 



Greatest width, anterior nares . . • . 



43 



34 



36 



44 



Length of mandible ...... 



168 



170 



171 



301 



Width between outer end of condyle . 



182 



168 



57 



205 



The vertebral formula was 



L, 



Ud, 



