232 



NATURAL HISTORY. 



the whiskers somewhat less profuse. Their brain is more spherical. In several minor particulars the 

 skull differs from that of the Otaries, and especially in the dentition is there a marked difference. 

 Three types prevail, of which the Common Seal, the Sea Leopards, and the Crested, or Hooded Seals, are 



examples. In the first, the dental formula is 

 Incisors, |=? ; canines, t|- ; premolars, ^ ; molars, 

 rj = 34. The differences in number and shape 

 in the two others we shall notice in the context. 

 "With respect to the skeleton generally, bone for 

 bone, the distinctions rather lie in their relative 

 lengths and dimensions than in special difference 

 of construction. The hip-bones, the hind leg- 

 bones, and those -of the fore feet, appreciably 

 differ and correspond to the peculiarities of pro- 

 gression, &c., in the two groups. On land, this 

 family (P/wcidce) lies on the belly, throws the 

 bind feet back, and by a series of short jerking 

 movements, so-called saltatory efforts, or a curious 

 kind of dragging motion, grovels abdominally on 

 the ground, the short fore-paws either pressed 

 against the body, or, on rocky rougher ground, 



otherwise . slightly aiding action. This movement of the Common Seal doubtless most people 

 have witnessed, and it is quite unique not only amongst the Carnivora, but the whole of the 

 Mammalia. In swimming, the Seals seldom use their fore feet, while the Otaries use them, as power- 

 ful sweeps. On the other hand, in the Seals the hind limbs have a kind of sculling movement, com- 

 parable to a fish's tail, the sinuous strokes bearing some analogy to those of a screw-propeller. Less 

 swift than the Otaries, they nevertheless move with extraordinary rapidity and power in the water. 



In the last family, the Eared Seals, it was pointed out that they had a peculiar geographical 

 distribution, wherein certain forms had alone a northern habitat, and similarly others pertained to a 

 southern. Almost identically, the Earless Seals have northern and southern representatives, but the 



TEETH OF COMMON SEAL 



SKELETON OF SEAL. 



Elephant Seal ranges both north and south ; and the Monk Seal, which, though properly speaking 

 belonging to the northern area, inhabits a strip running east to west within the Temperate zone, indeed 

 nearly approaching the Torrid. It is also worth mention that Van Beneden, Leidy, and others have 

 described quite a number of sub-fossil species, and Phocine genera ; though the data for the latter are 

 by no means complete, and probably future researches will considerably modify the conclusions arrived 

 at by these authors. These Seal remains have all been obtained in the Temperate parallel, and regions 

 where the sea no longer flows. In referring to the Earless Seals, as^in the case of the Otaries, we shall 

 somewhat follow their geographical distribution. 



THE COMMON SEAL.* This most familiar species of the group is as ludicrous in its gait on land 

 as it is surpassingly elegant in its movements in water. Its range is widespread, namely, the Black 



* Phoca vitulina, the genus Callocephalus of some authorities. 



