244 THE MAMMALS OF THE NORTH ATLANTIC 



the flanks, though there is much variation in the colour and markings. The body 

 is slender, the head small, the muzzle long and slender, and the front flipper nearly 

 three times as long as broad. Dolphins feed chiefly on fish, although some kinds 

 also eat crabs and shell-fish ; all associate in " schools " of larger or smaller siz«. 



Bottle-Nosed Nearly allied is the bottle-nosed dolphin (Tursiops tursio), which 



Dolphin, attains a length of 12 feet, and is sometimes grey in colour, in other 

 cases black above and pale grey below, but more generally leaden grey above, and 

 white below. The beak is shorter and thinner towards the end than that of the 

 common dolphin, and the body stoutly built. These dolphins congregate in schools 

 of considerable size, which are composed during pairing-time of about equal numbers 

 of males and females of all ages. In spring they are said to migrate north, and in 

 autumn south, but at Cape Hatteras, North Carolina, where they have been care- 

 fully observed, some are reported to frequent the same station throughout the year. 



Short-Beaked The group of short-beaked dolphins, which are mostly natives of 



Dolphins. warm and temperate seas, are characterised by the shortness of the 



head and the ill-defined beak. Among them, the white-beaked species (Lageno- 



rhynchus albirostris), which grows to a length of about 9 feet, inhabits the North 



Atlantic, where it ranges as far north as Greenland and Davis Strait. In colour it 



is generally purplish black on the back and whitish below, with the sides greyish, 



the muzzle whitish, and some whitish spots behind the blow-hole and near the base 



of the terminal fin. 



A second kind, the white-sided dolphin (L. acutus), resembles the last more or 



less closely in shape, but the head appears more swollen, the back-fin broader and 



more erect, and the flippers shorter. It attains a length of 8 feet, and inhabits the 



North Atlantic, where it is most common around the Orkneys. The colour is grey 



above and white below, with a wide yellowish band along the side enclosing a 



large white spot, a narrow black stripe extending from the dorsal fin to the tail, 



a similar stripe running from the base of the pectoral fin on to the head, and 



the eyes being ringed with black. There are several other members of this 



group of dolphins. 



In the so-called blackfish the rounded head has no distinct beak, 

 Blackflsh. 



the back-fin is long, low, and stout, the flippers are long and narrow, 



and the few teeth confined to the front half of the jaws. The common and widely 

 distributed blackfish (Globiocephalus melas), frequently called the pilot- whale, grows 

 to a length of at least 20 feet, and is wholly black, save for a large white spear- 

 shaped patch on the breast. This dolphin goes about in schools of a hundred or 

 more, always piloted by a leader a little distance in advance, who is followed 

 under all circumstances even when driven to destruction on a sandy beach. 

 Appearing frequently, although irregularly, on the northern and western coasts of 

 Europe, the blackfish seems to be scarce in the Mediterranean, but its range in- 

 cludes Greenland, the Cape of Good Hope, and New Zealand. 



, „ . . Resembling the last in general external appearance, Risso's dolphin 



Rissos Dolphin . ° b rr *_ 



(Grampus griseus) is distinguished by the head being less rounded, 

 the shorter flippers, the greater length of the pointed back-fin, and the very narrow 

 tail. This species is about 13 feet long, and mainly grey in colour, although greyish 

 white below, with the head and fore part of the body of a lighter or darker grey 



