ARCTIC MARINE ANIMALS. 



61 



enormous sjMrally wound tusk projecting from its upper jaw, and from which 

 it derives its ])opuhir name, has not yet been clearly ascertained, some holding 

 it to be an instrument of defense, "\^ hile others suppose it to be only an orna- 

 ment or mark of the superior dignity of the sex to which it has been awarded. 

 Among the numerous dolphins which people the Arctic and Subarctic seas, 

 the beluga [Delphinus ^eucas), improperly called the white Avhale, is one of the 

 most interesting. When young it has a brown color, wdiich gradually changes 

 into a perfect white. It attains a length of from twelve to twenty feet, has no 

 dorsal fin, a strong tail three feet broad, and a round head M'ith a broad trun- 

 cated snout. Beyond 56° of latitude it is frequently seen in large shoals, par- 

 ticularlv near tlie estuaries of the larci;e Siberian and North American rivers, 

 which it often ascends to a considerable distance in i)ursuit of the salmon. A 

 troop of belugas diving out of the dark waves of the Arctic Sea is said to afford 



'/:t-- .■■^v^.l^:^^ 



THE NARWHAL. 



a magnificent spectacle. Their white color appears dazzling, from the con- 

 trast of the sombre background, as they dart about with arrow like velocity. 



The black dolphin ( Globlcephalus globiceps) is likewise very common in 

 the Arctic seas, both beyond Bering's Straits and between Greenland and Spitz- 

 bergen, whence it frequently makes excursions to the south. It grows to the 

 length of twenty-four feet, and is about ten feet in circumference. The skin, 

 like that of the dolphin tribe in general, is smooth, resembling oiled silk ; the 

 color a bluish-black on the back, and generally whitish on the belly ; the blub- 

 ber is three or four inches thick. 



The full-grown have generally twenty-two or twenty-four teeth in each jaw ; 

 and when the mouth is shut, the teeth lock betw^een one another, like the teeth 

 of a trap. The dorsal fin is about fifteen inches high, the tail five feet broad ; 

 the pectoral fins are as many, long and comparatively narrow ; so that, armed 

 with such excellent paddles, the black dolphin is inferior to none of his relatives 

 in swiftness. Of an eminently social disposition, these dolphins sometimes con- 

 gregate in herds of many hundreds, under the guidance of several old experi- 



