158 



DR. SIDNEY F. HARMER ON CETACEA 



diameter of as much as in. As indicated by its name, the 

 head has a well-marked beak, about 3 in. long. 



(12) White-beaked Dolphin (Lagenorhyhchus albirostris Gray). 



Eight records : one from the North coast of Ireland (March, 

 1917), one from the Island of Islay (Oct., 1913), and the remainder 

 from the Eastern coast, from Caithness to Lincolnshire — to which 

 may be added three specimens stranded in Suffolk and Kent in 

 February, 1918. A lthough the two species are known to overlap 

 in their distribution, it is noteworthy that in this series of 

 observations the distribution of the White-beaked Dolphin 

 and of the Bottle-nosed Dolphin have not overlapped and are 

 complementary to one another. 



The Wliite- beaked Dolphin is characterized, as indicated b}^ its 

 popular name, by possessing a well-marked short beak, which is 

 white in colour. It reaches a length of rather more than 9 ft. 

 Its teeth are about 25 on each side of each jaw, but are distinctly 

 smaller than those of the Bottle-nosed Dolphin, their basal 

 diameter being about yg'Ts ni - 



(13) White-sided Dolphin (Lagenorhynchus acutus Gray). 



Three records: Fair Island, between the Orkneys and the 

 Shetlands (March, 1913); Lincolnshire (May, 1917); Co. Mayo 

 (June, 1916). 



This species, which is said to be one of the commonest of the 

 Cetacea oft* the Norwegian coast, where it may occur in schools of 

 as many as 1000 individuals (cf. Hjort, 1902, p. 118), maybe 

 regarded as a boreal species which does not often occur in our 

 seas. Most of the specimens previously found have been from 

 the Orkneys and other parts of Scotland ; and one or two have 

 been noticed from Ireland. So far as I am aware, the Lincoln- 

 shire specimen here recorded is the first to have been obtained on 

 the English coast. 



The White-sided Dolphin has a characteristic longitudinal 

 whitish area on each side, in the middle and posterior half of its 

 body. Its teeth are smaller (basal diameter about -fy in.) and 

 more numerous (about 30 to 35 visible during life on each side of 

 each jaw) than in the White-beaked Dolphin, from which it 

 differs in certain other respects, the following of which may be 

 noticed. The beak, which resembles that of L. albirostris, 

 is black. The pectoral fins are falcate, with a very convex lower 

 border ; those of the other species being blunter and broader, 

 and less convex below. These fins, moreover, originate from the 

 white part of the body, being connected with the black part of 

 the head by a narrow dark streak ; while in L. albirostris the 

 black of the dorsal surface extends as far as the base of the 

 flipper (cf. Liitken, 1887, pp. 377, 386, 395). L. acutus is said 

 to reach a length of about 12 feet (Hjort, 1902, p. 117). 



