PORPOISES AND DOLPHINS. 49 



not ascending very far, and the sounds among the reefs and islands. It feeds 

 chiefly on prawns, also on small cephalopods and fish. It does not appear to herd 

 in schools, more than four or five, being rarely, if ever, seen together. Usually 

 it is solitary ; the pairs seem to consist of female and calf, more often than male 

 and female. The young (one in number) are born, apparently, about October. The 

 roll of this porpoise is like that of P. communis. It does not jump or turn somer- 

 saults, and is, on the whole, a sluggish little porpoise." It appears to be found 

 only in shallow water. 



HEAVISIDE'S DOLPHIN. 

 Genus Cephalorhynchus. 



Heaviside's dolphin (Cephalorhynchus heavisidei), from the Cape of Good 

 Hope, is the typical representative of a genus which, according to Mr. True, 

 includes four species, all inhabiting the warmer seas of the Southern Hemisphere. 

 These dolphins are of small size, and remarkable for their peculiar coloration. 



HEAVISIDE'S DOLPHIN. 

 (From True, Bulletin of the U.S. National Museum, 1889.) 



The head is conical, without any distinct beak ; and the teeth are small and sharp, 

 varying in number from twenty-five to thirty-one on each side of the jaws. The 

 back-fin is triangular or ovate ; and, except in one species, the flippers have a 

 characteristic elliptical form. The coloration is black above and white below ; the 

 white of the under-parts terminating posteriorly in a trident-shaped form, with the 

 lateral prongs of the trident extending obliquely upwards on the sides. The total 

 length of Heaviside's dolphin is about 4 feet ; the number of teeth being from 

 twenty-five to thirty. The white-fronted dolphin (C. albifrons), from New 

 Zealand, is a rather larger species, with thirty-one teeth on each side. Nothing 

 seems to be recorded as to the habits of these species. 



THE IRAWADI DOLPHIN. 

 Genus Orcella. 



The upper waters of the Irawadi River are tenanted by a rather large dolphin 

 or porpoise (Orcella fluminalis), which, together with a closely allied species, or 

 variety (0. brevirostris), from the Bay of Bengal and its estuaries, as well as 

 Singapore and Borneo, constitutes a distinct genus. These dolphins are characterised 

 by their globe-like head, without beak, and their comparatively few and small 

 teeth, which occupy nearly the whole length of the jaws, and number from thirteen 



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