134 



CARNIVORES. 



behind. Dr. Murie has, however, ascertained that in the case of the Greenland and 

 crested seals there is a kind of motion somewhat intermediate between the above 

 and that characteristic of the eared seals. Thus the former of these two species 

 " very often uses its fore-limbs, placing these on the ground in a semi-grasping 

 manner, and, by an alternate use of them, drags its body along. The hind-legs 

 meantime are either trailed behind slightly apart, or with opposed plantar surfaces 

 slightly raised and shot stiffly behind. On uneven ground, or in attempting to 

 climb, a peculiar lateral wriggling motion is made ; and at such times, beside alter- 

 nate palmar action, the body and the hind-limbs describe a sinuous spiral track." 

 On the other hand, the common seal appears far less capable of making use of its 

 fore-limbs in progression on land, these being only occasionally employed to obtain 

 a hold on rocks. 



On smooth ice seals are able to progress with considerable rapidity ; the 

 average rate being about one mile an hour in cool weather. Such journeys are 

 always undertaken during the night ; and the seals advance by raising their bodies 

 from the ice by means of the fore-limbs, and then drawing themselves forward. 

 On land, seals will occasionally travel considerable distances ; and it is on record 

 that in the winter of 1829 a grey seal in Norway travelled through the snow a 

 distance of fully thirty miles; the time occupied in accomplishing this journey 

 being believed to have been about a week, during which period the creature could 

 not have touched food. 



The true seals are not a very ancient group, geologically speaking, although 

 their remains are found through the Pleistocene and Pliocene strata, and in a portion 

 of those belonging to the Miocene period. Fossil seals are very common in the 

 Pliocene deposits of Belgium ; most of them being more or less nearly allied to the 

 species now inhabiting the Northern Hemisphere. It is very noteworthy that while 

 true seals range downwards to the Miocene period, no remains which can be 

 definitely assigned to the eared seals have hitherto been discovered in any but the 

 most recent and superficial deposits. If this apparently late origin of the eared 

 seals be confirmed by future researches, it will go far to confirm the suggestion 

 that the latter have taken rise from land Carnivores quite independently of the 

 true seals. 



The Grey Seal. 



Genus Halichoerus. 



The grey seal (Halichoerus grypus), which is the sole representative of its 

 genus, belongs to a group confined to the Northern Hemisphere, and distinguished 

 from all the other members of the family by the presence of three pairs of incisor 

 teeth in the upper jaw, and two pairs in the lower jaw. A further characteristic 

 of the group is to be found in the presence of claws on all the toes of both pairs of 

 limbs ; while all those of the hind-feet are of nearly equal length. 



The grey seal is at once distinguished from the other members of this group by 

 the circumstance that the crowns of the relatively large cheek-teeth are composed 

 of but a single conical cusp, although there may occasionally be fore-and-aft cusps 

 in the last two teeth of the lower jaw. Another peculiar feature of these teeth is 



