THE BRITISH MAMMALS : THEIR GENERA AND SPECIES. 59 



height is less than its base. The flippers are ovate in shape and 

 twice as long as the dorsal is high, being about a seventh of the 

 total length of the body, which is under six feet. The white of the 



PORPOISE. 

 (Phocana communis.) 



underparts does not extend on to the flippers, the tail or, in some 

 cases, the lower jaw. The porpoise is generally caught in nets into 

 which it blunders in pursuit of the fishes on which it feeds. 



Physeter. Plate xxii. GET ACE A. 



59. macrocephalus, SPERM WHALE. Head massive, measuring a third of 

 total length, truncated in front ; lower jaw long, 

 narrow, and toothed. 



The Sperm Whale is a rare visitor whose visits to Britain, dead 

 or alive, are becoming rarer. The huge, clumsy head contains the 

 largest skull extant a skull which is not symmetrical, the right jaw 

 being larger than the left, and the right nasal being absent. In the 

 upper jaw the teeth are rudimentary and embedded in the gum, but 

 there are from twenty to twenty-five pairs in the lower jaw, which ij 

 long and narrow, with the branches united for more than half then 

 length. The throat is expansible and has two grooves. The eye is 

 slightly above the angle of the mouth. The blow-hole only one as in 

 all the toothed whales is the shape of a violin sound-hole, and placed 

 on the left side near the front of the muzzle, so that the jet is more 

 forward than upright, and by the angle of the spout the Sperm 

 Whale can be identified at a distance. The flippers are a tenth of 

 the total length, and obliquely truncated ; the back fin is represented 

 by a series of low humps ; the tail is deeply cleft, and the flukes, as 

 in many other whales, are alternate, like the blades of a screw 

 propeller. The length over all is sixty feet or less, the female being 

 much smaller than the male. The colour is black above shading 

 into grey below. The Sperm Whale, huge as it is, can leap clear 

 out of the water. It feeds to a large extent on fishes, ranging from 



