FOOD OF MARINE MAMMALS 77 



congregate both in spring and autumn around tlic Pribylov 

 Islands in the North Pacific, to feed on the fur seals which 

 breed there. The destruction caused by them is very great. 

 The stomach of one killer contained eighteen seals and that of 

 another twenty-four; each had consumed fur of the value of 

 some £400 to £500 according to the sealers' estimate. Both 

 killer-whales and seals annually migrate southward, but what 

 happens then is unknown. 



You mustn't swim till you're six weeks old, 

 Or your head will be sunk by your heels; 



And summer g,a\es and Killer Whales 



Are bad for baby seals. Kiplino 



There is a special genus of dolphin which inhabits the 

 Cameroon River, and it alone amongst the Cetacea is said 

 to be herbivorous, living on water weeds. 



The SiRENiA or Sea-cows (the Dugong and Manatee) are 

 as aquatic as the whales and apparently never come on land. 

 They live on sea-weeds and water-plants. They pass their 

 life in the shallow waters of the tropics and are common 

 about the mouths of rivers, which they often ascend. For 

 the most part they live a placid existence under water with 

 their body arched, their tail and head being bent in beneath 

 the body. Of three specimens observed in an aquarium, a 

 male and a female and a young one, the male came to the 

 surface more frequently to breathe than the female. The 

 young specimen remained below the surface on an average 

 four and a half minutes, with a maximum of nine and a half 

 minutes, whereas the larger specimens would remain sul)- 

 merged for periods of twelve minutes and on occasions for 

 sixteen minutes. Thus the Sirenia like the Cetacea are very 

 greatly specialized for an aquatic life. 



The great order of Ungulata includes the two small 

 groups of the Hyracoidea or conies and the Pkoboscidea 

 or elephants and two large groups, the Perissodactyla or 

 the odd-toed ungulates, horses, tapirs and rhinoceroses, and 

 the Artiodactyla, the even-toed ungulates, hip])opotamuses, 

 pigs, camels, deer, giraffes, sheep and oxen. These are the 

 greatest source of food for the terrestrial carnivorous animals, 

 which we shall consider later. In the main it is in tlie 



