Maniinalia. 1 1 



variable number of, it is true, rudimentary claws on the hind- 

 Hippers of each species. 



It seems improbable that we shall ever approach more nearly to 

 an understanding of the true inter-relationships of the Phocidac until 

 we discover some of the ancestral forms from which they have 

 sprung.^ Possibly the various genera left the ancestral tree at various 

 epochs, and, if we are to follow Sir William Flower, we have in 

 Macrorhinus the most highly specialised form of the whole group. 



As to the Stenorhynchinae, they must be regarded as the 

 descendants of an ancestor which became isolated from the pre- 

 cursors of the remaining two sub-families at a sufficiently early 

 period to allow of the formation of the various distinct genera which 

 now exist. The exact relationships of these amongst themselves 

 cannot, I think, be more clearly indicated than has been attempted 

 above. Ommatophoca is certainly the most distinct, and may be 

 regarded as annectant between the Stenorhynchinae and Ci/stopJiorinae. 

 If any convenient result would accrue therefrom, it might be taken 

 to constitute a separate sub-family, the Ommatophocinac, but I do 

 not see how the multiplication of sub-families can help us much. 



A certain amount of light on the origin of some of the genera 

 may, perhaps, be derived from the young. Thus the young of 

 Haliclicerus, a genus which has not at the present day an Arctic 

 haljitation, are white (or nearly so), thereby permitting the suspicion 

 that its ancestors were of Arctic origin, or, at least, dwellers in regions 

 where the cold was more intense than those which they at present 

 frequent. On the other hand, the only Seal of the Antarctic, which 

 is nearly white, is Lobodon, and its mottled young suggest a com- 

 paratively recent inroad of the species into the cold regions of 

 the South Polar area. 



It is interesting to find the teeth of Phoca hispida paralleled iu 

 the south by those of Ogmorhinus, while the teeth of Leptonychotes 

 recall those of P. vitulina, and Monaclius, in this respect to a certain 

 extent, resembles Halichoerus. 



Dentition. — The teeth of the Phocidae are remarkable for the 

 extreme variation which they display in the genera. In most cases 

 dental characters present the most distinct features between animals 

 which are externally very similar. In the skins, as seen in museums, 

 Leptonychotes and Lobodon are, but for their colour, difficult to 

 separate, yet nothing could be more distinct than the forms of their 



* StenorhyncJius vetns of Leidy is so close to (if not identical with) Lohodau 

 carcinoj^kaguH thai it affords us no iidii whatsoever. 



