194 



THE FOOD OF ANIMALS 



It has already been pointed out (p. 7) as a rule of general 

 application that the digestive tract is relatively longer in creatures 

 which live on vegetable food than in those which subsist on 



Fig. 434. Tadpoles 



animal matter. The Frog is a very interesting application of 

 this rule, for we find that in the tadpole the intestine, here coiled 

 like a watch-spring, is relatively longer than in the adult animal. 



FISHES 



Lung-Fishes (Dipnoi), Sharks and Rays (Elasmobranchii), 

 and the Ganoid group (Sturgeons, &c.) of the Teleostome fishes 

 are exclusively or mainly carnivorous, and the same is true for 

 most families of the ORDINARY BONY- FISHES (Teleostei) which 

 constitute the great bulk of the last-named subdivision. A good 

 many of the Teleosts, however, are mixed feeders, and a few are 

 vegetarians pure and simple. Among these last may be mentioned 



