5 8 CETACEANS. 



behind the other, and more or less mottled with darker tints. There is also a 

 similar light area behind the blowhole on the back, and another near the root of 

 the flukes. There is, however, considerable individual variation in regard to 

 the coloration. When freshly-stranded specimens come under observation, the 

 black of the back is often seen to be shot with a rich purplish tint, and the whole 

 coloration is then exceedingly beautiful. There are usually about twenty-six 

 teeth on each side of the jaws; and the length attained by adults is from 

 8 to 9 feet. The white-beaked dolphin inhabits the North Atlantic, the North Sea, 

 and the Baltic, ranging as far northward as Greenland and Davis Strait. Between 

 the years 1834 and 1885, a total of nineteen specimens of the dolphin had been 

 taken in British waters ; and since the latter date a specimen was taken on the 

 Irish coast in 1887, and a third in the river Colne in 1889. 



THE TRUE DOLPHINS. 

 Genus Delphinus. 



The true dolphins bring us to the first genus of the second great group of the 

 family, which includes all the forms with distinct beaks, except the short-beaked 

 dolphins just described. The beak is generally distinctly marked off from the 

 forehead by a V-shaped groove ; and in the skull the beak considerably exceeds 

 the brain-cavity in length. In the skeleton the first two vertebrae of the neck are 

 united, but the other five remain separate. All the members of the group are of 

 comparatively small size, most of them not exceeding 10 feet in length. Dolphins 

 associate in shoals, and feed mostly on fish, although some of them at least also 

 consume crustaceans and molluscs. 



The common dolphin (Delphinus delphis), which apparently 

 frequents all temperate and tropical seas, is the typical representative 

 of the genus Delphinus, which presents the following characteristics. The beak 

 is long, and the back-fin and flippers are elongated and falcate. In the skull the 

 bony beak is long and narrow, and generally about twice the length of the region 

 of the brain -case. The jaws are furnished with a numerous series of teeth, 

 varying from about forty to sixty-five on each side, which are sharply pointed, with 

 their bases oval in section. The bony union between the two branches of the 

 lower jaw is short. 



The common dolphin has a slender body and small head ; the beak being long 

 and narrow, and the flippers about three times as long as broad, with their 

 extremities pointed. There is considerable individual variation in colour, but 

 usually the back is dark grey, the under-parts white or whitish, and the flanks 

 marked by varying bands of grey or fulvous. The length of the animal is about 

 7J feet, and there are from forty-one to fifty teeth in the upper, and from forty- 

 five to fifty-one in the lower jaw. 



There seems no doubt that this species is the dolphin of the 



ancients, although the pictorial representations on old coins, and 



the descriptions of the habits of the animal which have come down to us from the 



writers of antiquity, are alike untrue to nature. The species is occasionally met 



