2 2 BRITISH MAMMALS 



tusk, perhaps as much as 6 ft. in length occasionally. This 

 tusk grows out horizontally through bone and flesh, inclining 

 towards the middle of the skull. The corresponding tooth on 

 the right side of the upper jaw remains usually quite rudimentary. 

 Occasionally, however, both teeth are developed, though this is 

 a rare occurrence. The narwhal being practically toothless, it 

 is apparently unable to feed on the larger kinds of fish, and its 

 diet is said to consist mainly of octopuses, small crustaceans 

 with soft shells, and small fishes. Scoresby, however, relates 

 that he found the remains of a large flat-fish in a narwhal's 

 stomach, and thought it probable that the male narwhal used 

 his tusk to spear large fish. This, however, seems improbable, 

 since the mouth of the narwhal is too small to take in a fish of 

 any considerable size, even if it succeeded in detaching it from 

 the long tusk, while, as it has no biting teeth, it could not tear 

 off morsels. It is pretty certain that the main use of the tusk is 

 in battles between the males for the possession of the females. 



Delphinapterus leucas. Beluga,^ or White Whale 



The White Whale is in many respects a less specialised form 

 than the narwhal, and no doubt represents more or less nearly 

 the stock from which the narwhal evolved. But it has no long 

 tusk. On the other hand, the permanent dentition consists of 

 as many as ten teeth on each side of each jaw — teeth which 

 are simple cones in the young animal, but become, by use, 

 flattened stumps. The young belugas are generally slate colour, 

 fading into grayish-white on the under parts, but the adults 

 become pure white all over — a white which is soAetimes tinged 

 with oyster-gray or with a pinkish tint.^ The beluga is not 

 known to exceed la ft. in length. 



1 This is a Russian name, derived from the adjective meaning white. 



^ Nordenskiold, who saw much of this whale when coasting along the 

 arctic shores of Siberia, describes the adult beluga as singularly beautiful, its 

 glistening white hide showing scarcely a scratch or a wrinkle. Two young 

 male belugas, which were cast ashore in Pentland Frith in 1793, were 

 mottled with brownish-gray, the mottles somewhat resembling the spots of 

 the narwhal. 



