196 BRITISH MAMMALS 



hind limbs for locomotion on land, the True Seals cannot travel 

 very far from the water's edge. Such progress as is made over 

 the rocks or on ice or sand is by wriggling the body in a 

 serpentine course, occasionally using the fore limbs to grasp 

 uneven surfaces, pushing them forward alternately. When land- 

 ing on rocks or on ice they raise their bodies nearly erect, and 

 hoist themselves up out of the water by means of their fore 

 limbs. In spite of these disadvantages seals manage to accomplish 

 considerable distances during the night (they rarely travel in the 

 daytime) on land. 



In the skull of the True Seals there is no alisphenoid canal, 

 and the angle of the lower jaw lacks that inflection characteristic 

 of the Otariids, the Creodonts, and the Marsupials. The 

 testes never descend from the abdomen into a scrotum, and the 

 palms and soles of the feet are hairy, and not naked or warty as 

 in the sea lions and walrus. There is no woolly under-fur as in 

 the sea lions (who are the "fur" seals of commerce), but the 

 skin of nearly all True Seals is covered with stiff, shiny closely- 

 pressed hair, and this coat is nearly always more or less marked 

 with spots or blotches of dark on light. In this spotted 

 nature of their coat the True Seals differ markedly from the 

 sea lions and the walrus, both of which groups are absolutely 

 one-coloured. Seals generally possess two pairs of mammas on 

 the abdomen. The young are invariably brought forth On the 

 land, and have to be taught to swim by their parents. They 

 take to the water with some reluctance. 



True Seals are polygamous, but do not have such a strongly 

 marked rutting season as is the case amongst the sea lions (a 

 period of something like three months, in which the male almost 

 entirely abstains from food). They are, however, equally 

 gregarious. 



SUB-FAMILY: PHOCIN^E. THE COMMON SEALS 



In this sub-family the incisor teeth number three pairs in the 

 upper jaw and two pairs in the lower. There are five well- 

 developed claws on all four feet. In the hind limbs the first toe 



