272 MAMMALS AND BIRDS OF THE ARCTIC 



total length, and the high roof formed by the upper jaw and the great lateral 



expansion of the two branches of the lower jaw make the capacity of the mouth 



enormous. This whale, in spite of its colossal dimensions, feeds on minute 



invertebrates, which it is compelled to swallow in immense quantities ; hence the 



necessity for the great size of the mouth. 



The second member of the exclusively Arctic triad of cetaceans 

 Narwhal. 



is the narwhal (Monodon monoceros), the males of which are 



characterised by the presence of one (generally the left) spear-like and spirally 



twisted tusk, projecting straight out from the upper jaw and reaching a length of 



8 to 10 feet. Occasionally both tusks are developed, in which case each has 



the same spiral. The right tusk, as a rule, however, remains undeveloped, as is the 



case with both those of the female. The narwhal — that is to say the corpse- whale — 



takes its name from the pale grey colour of the skin, this grey tint passing into whitish 



on the under-parts. There is no back-fin, and the flippers are short and rounded. 



In distribution the species is circumpolar, and it is seldom seen south of the Arctic 



Circle. Narwhals go about in small parties, and feed on squids and cuttles, 



crustaceans, and fishes. The tusk is probably employed as a fighting weapon 



in combats between rival males. 



The third member of the group is the white whale, or beluga 

 White Whale. . ... . 



(Delphinapterus leucas), distinguished from all its relatives by the 



glistening buffish white skin of the adult, the colour of the calves being light 



greyish brown. The head is rounded, like that of the narwhal, and, as in that 



species, the back-fin is represented merely by a slight ridge. The white whale 



is a purely Arctic species, although it occasionally wanders so far south as the 



Scottish coast. It is of fair commercial importance on account of its skin 



furnishing some of the leather sold under the name of porpoise-hide. Attaining 



a length of 16 feet, this cetacean is reported to feed chiefly on salmon. From 



the peculiar sound emitted as it rises to breathe, it is sometimes called by sailors 



the sea-canary. 



The birds of the Arctic are chiefly those of swimming habit, 

 Brent-Goose. . . ° 



among them being the sea-geese which frequent the shores, and 



generally breed in one or other of the polar regions. In these birds the beak is 



shorter and deeper than in ordinary geese, the cutting edge of its lower half being 



sbraighter and the serrations on the upper half invisible externally. One of the 



most familiar members of the group is the brent-goose (Branta bernicla), which 



appears annually in large numbers on certain parts of the shores of the Baltic and 



North Sea in winter. This species inhabits the high north of Europe, Asia, and 



North America, and breeds within the Arctic Circle. It feeds by day, and seems 



to avoid the company of its cousin the bernicle goose, whose feeding-time is always 



the night. A well-grown brent-goose will measure about 22 inches in length. The 



species may be easily recognised by the jet-black head, and the presence of a white 



patch on each side of the neck. 



The nearly allied bernicle goose (B. leucopsis) differs by 

 Bernicle Goose. . J ° 1 ' J 



having the head white, with a black crown and nape and a black 

 stripe from the eye to the beak. Migrating in smaller flocks than the brent-goose, 



