PORPOISES 



1219 



the fin, as the porpoise swims along in a series of gentle curves; while at another 

 the white belly will flash in the sunlight as the creature turns on its side, or leaps 

 completely out of the water. In the ordinary undulating mode of swimming, the 

 porpoise just brings its blowhole to the surface, breathes without checking its course, 

 and then dips dow r nward, to expose the back fin in the manner represented in our 

 second illustration; this elegant motion being continued without intermission. 

 Throughout its course, the flukes are the propelling instrument; the flippers being 

 laid close against the sides during the onward movement, and only spread out to 

 check its speed when the animal desires to stop. The food of the porpoise appar- 



THE COMMON PORPOISE. 

 (One-fifteenth natural size.) 



ently consists exclusively of fish; mackerel, pilchards, and herrings, being its 

 especial favorites, although it also consumes salmon. On the British coasts 

 porpoises may frequently be seen in pursuit of shoals of mackerel and herrings, and 

 when thus engaged are often caught in the nets set for the latter. The pairing sea- 

 son is said to be in the summer, and it is believed that the single offspring is pro- 

 duced after a period of six months' gestation. Three porpoises which were inclosed 

 by a fence in the Wareham river in Dorsetshire, many years ago, are reported to 

 have incessantly uttered the most distressing cries, which were continued by night 

 as well as by day. 



