733 



MANUAL OF ZOOLOGY. 



act as organs of touch. The seals are very largely captured for the sake of 

 their blubber and skins. 



The only common British seal is the Phoca vitulina, which occurs not 

 uncommonly on the northern shores of Scotland, and ranges over almost 

 the whole of the shores washed by the North Atlantic and the seas of 

 Greenland. It is yellowish-grey in colour, and measures from three to 

 five feet in length. Other seals attain a much greater length the Great 

 Seal measuring from eight to ten feet, and the Elephant Seal (Macro- 

 rhinus) of the South Pacific, reaching a length of twenty feet. 



The Eared Seals or Sea-lions (Otariada:) differ from the typical Seals in 

 the possession of small conical ears, and in the much greater freedom of the 

 limbs, enabling the animal to walk with comparative ease on land. The 

 Eared Seals are principally found on the shores of the continents and 

 islands washed by the Pacific ; but they are also found in the extreme 

 southern part of the Atlantic as far northwards as the mouth of the Rio 

 Plata. 



The third family of the Pinnigrade Carnivores is that of the Triche- 

 cidce, comprising only the Walrus or Morse (Trichecus rosmarus). The 

 chief peculiarity by which the Walrus is distinguished from the true Seals 

 is found in the dentition. According to Owen, there are six incisors in 

 the upper jaw and four in the lower ; but these are only present in the 

 young animal, and soon disappear, with the exception of the outermost 

 pair of upper incisors. The upper canines are enormously developed, 

 growing from persistent pulps, and constituting two large pointed tusks, 

 which attain a length of over fifteen inches (fig. 427). The direction of 



Fig. 427. Skull of the Walrus (Trichecus rosmarus), after Owen. 

 i Tusk-like upper canines. 



the tusks is downwards and slightly outwards, and they project consid- 

 erably below the chin. The upper jaw has three prsemolars and two 

 molars, with flattened crowns, on each side, and the lower jaw has the same 



