TISSES. 213 



water, they need no eyelids and no tear-apparatas, and 

 accordingly have none. For protection of the eye the 

 skin is continued over it, but it is so thin that the light 

 is readily transmitted through it. The organs of the 

 sense of smell are better developed than those of any 

 other sense, and its smell is therefore acute, undoubtedly 

 to aid it in the search of its food. Its sense of taste, on 

 the other hand, is dull, probably because, for the most 

 part, the food is swallowed whole, and is not detained 

 long in the mouth. -^ 



359. Fishes are very voracious, and their food is most- 

 ly animal, few, comparatively, feeding upon vegetables. 

 Some live on the soft>-bodied animals floating in great 

 numbers in the sea, of which I shall treat in another part 

 of this book. Others live on shell-fish, and animals that 

 are covered with a hard crust, such as lobsters, crabs, 

 etc. Many fishes in fresh water live on- worms and the 

 grubs of insects. Then, too, fishes feed to a large extent 

 on fishes that are smaller than themsi^ves. In this re- 

 spect such fishes have a Tcsenxblance to the carnivorous 

 Mammals, Birds, and Reptiles. It is stated that, " at a 

 lecture delivered before the Zoological Society of Dublin, 

 Dr. Houston exhibited, as ' a fair sample of a fish's break- 

 fast,' a Frog-fish two and a half feet long, in the stomach 

 of which w.is a Codfish two feet in length. The Cod's 

 stomach contained the bodies of two Whitings of ordi- 

 nary size ; and the Whitings, in thei." turn, held the half- 

 digested remains of many smaller fishes too much broken 

 np to be identified." 



360. The mouth of each fish is adapted to its mode of 

 gaining a livelihood. Some species have no teeth, but in 

 most fishes there are several rows of them. They are 

 commonly not confined to the jaws, but are also on the 

 tongne, the palate, etc. Most have teeth merely for hold- 

 ing the food and passing it into the throat, while in oth- 

 ers there are teeth for cutting or tearing ; and in such as 

 live on shell-fish there are teeth for crushinjr. 



