18 THE ANGLER-NATURALIST. 



tive process very rapid — so rapid, in fact^ in some of the 

 carnivorous species as to have been compared to the action 

 of fire. I have mentioned elsewhere the case of a pike 

 taken with a large eel sticking in his throat half swal- 

 lowed, the head-portion being already semidigested, whilst 

 the tail, still alive and struggling, protruded from his 

 jaws. The digestive process is most rapid, and the in- 

 testines shortest, in those species which live principally, or 

 wholly, on animal food; and the intestines are consider- 

 ably longer, and the digestion proportionably slower, in 

 those which feed on vegetable substances. The same prin- 

 ciple is observable amongst other classes of the Animal 

 Kingdom. 



In some species, such for instance as the Grey IMuUet 

 and the Gillaroo Trout, which swallow their prey whole, 

 the walls of the stomach are thickened, so as to afford in- 

 creased muscular power ; and in such species the stomach 

 has a considerable resemblance to the gizzard of a bird. 

 The intestines and stomach differ materially in different 

 families. 



The kidneys are situated under and against the spine. 



The Brain. 



The brain of fishes, which is exceedingly small in pro- 

 portion to their size, is formed by an enlargement of the 

 extremity of the nervous axis, or spinal marrow, and is 

 disposed as in reptiles, with the addition of ' nodes ' or 

 ' ganglions ' at the base of the nerves of smell. The pro- 



