PORPOISES AXD DOLPHIXS. 



47 



Few sights are, indeed, more interesting than to watch a shoal of these animals 

 diving and sporting round a vessel, whether it be making rapid headway, or lying 

 at anchor. At one moment will be seen the roll of the arched back, surmounted 

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

 the white belly will ilash 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 1 irings its blowhole to the surface, breathes without checking its course, 



ponroisE diving. 



and then dips downwards, 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- 

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

 especial favourites, 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- 

 season is said to be in the summer, and it is believed that the single offspring is 



