CHANGE OF FOOD IN GULLS. 



61 



of the species as such might be made possible if the surviving 

 specimens could quickly accustom themselves to the eflfects of a 

 change of food. Such an accommodation to a new diet, not 

 properly suitable to the animal, might be expected to be almost 

 impossible to monophagous creatures, but to the polyphagous 

 far less so. 



However, many animals of both groups are already known 

 which are able, intentionally or under compulsion, to change 

 their food, and in a corresponding degree their mode of life. 

 The well-known anatomist and physiologist, John Hunter, long 



Pig. 15. — Myopotamus Coypu. 



since communicated his observation that a kind of gull, Larus 

 tridactylus — can live on grain, although its stomach is adapted 

 to flesh diet; it commonly feeds on fish. Another species, 

 Larus argentatus, is said by Dr. Edmonstone to live in the 

 Shetland Islands on grain in the summer, and on fish in winter. 

 In the same way the Coypu — Myopotamus Coipu — living in 

 the Chonos Islands, off the western coast of South America, 

 has accommodated itself to an animal diet ; it there chiefly eats 

 the marine mollusca of the coast, where alone the creature is 

 found; on the n^ainland, high up the country, it feeds, exclu- 

 sively on roots, which it digs out on the shores of streams and 



