306 Zoological Society : — , 



In the younger specimen the edge of the palate has a sUght pro- 

 minence in the middle of each side ; bnt this is evidently an acci- 

 dental deformity, as the prominences are not of the same size m the 

 two sides. In the adult skull the two sides of the palate are evenly 



arched out. , 



The lower jaw most resembles that of the restricted genus Fhoca 

 (of which P. barbata is the type) in being solid and strong, and in 



Fig. 1. Skull of Halicyon Richardii. 



2. End of lower jaw of Phoca barbata, to show the dilatations and inflexions 



of the lobe over the angle. 



3. End of the lower jaw of Pagomysfcelidm. The end of the jaw of CaUo- 



cephalus vitulinus is somewhat similar. 



4. Lower edge of the lower jaw of Halicyon Richardii. 



5. Lower edge of the lower jaw of Phoca barbata. 



6. Lower edge of the lower jaw of Pagophilus grcenlandicus. The jaw of 



Pagomys /oelidus is somewhat similar, hut much smaller. 



