578 MANUAL OF ZOOLOGY. 



teeth in both jaws : the teeth being numerous, and conical in 

 shape. The nostrils, as in the last family, are united, but they 

 are placed further back, upon the top of the head. The single 

 blow-hole or nostril is transverse and mostly crescentic or lunate 

 in shape. The head is by no means so disproportionately large 

 as in the former families, usually forming about one-seventh of 

 the entire length of the body. 



The most noticeable members of this family are the true 

 Dolphins, the Porpoises, and the Narwhal. 



The Dolphins have an elongated snout, separated from the 

 head by a transverse depression. The common Dolphin (Del- 

 phinus delphis, fig. 247) is the best-known species. It aver- 

 ages from six to eight feet in length, and has the habit of swim- 

 ming in flocks, often accompanying ships for many miles. The 



Fig. 247. The common Dolphin (Delphinus delphis). 



female, like most of the Cetacea, is uniparous. The Dolphin 

 occurs commonly in all European seas, and is especially abun- 

 dant in the Mediterranean. 



The common Porpoise (Phoccena communis) is the commonest 

 and smallest of all the Cetacea, rarely exceeding four feet in 

 length. The head is blunt, and is not produced into a pro- 

 jecting muzzle. The Porpoise frequents the North Sea, and is 

 commonly seen off our coasts. Another British species is the 

 Grampus (Phoccena orca), but this is much larger, attaining a 

 length of from eighteen to twenty feet. Nearly allied to the 

 Grampus is the so-called " Caing " Whale, or, as it is some- 

 times termed, the "Bottle-nosed" Whale (Globicephalus or 

 Phocana globiceps). This species occurs not uncommonly 

 round the Orkney and Shetland Islands, and attains a length 

 of as much as twenty-four feet. It is gregarious in its habits, 

 and is often killed for the sake of its oil. 



Closely allied to the true Dolphins are two curious Cetaceans, 

 belonging to different genera, but both inhabiting fresh waters. 

 One of these is the Gangetic Dolphin (Platanista Gangetica], 

 which inhabits the. Ganges, especially near its mouth. This 



