FISHES. 313 



by some of the northern nations. In Norway, and even in 

 some of the remote districts of our own country, fish bones 

 are given as food for cows, and are greedily devoured by 

 them. 



The ORGANS OF MOTION present many striking pecu- 

 liarities. 



If we attend to the vast variety of forms, exhibited by 

 different kinds of fish, we shall be disposed to conclude, 

 that shape exercises but little influence on their movements. 

 While some are cylindrical and lengthened, others are 

 nearly globular : some are depressed, while others are com- 

 pressed. The general form, however, approaches to ovate, 

 the body being thickest at the thorax, and tapering a little 

 towards the head and tail. 



The fins of fishes correspond with the wings of birds, 

 the former being calculated to give the motion to the body 

 in the water, the latter in the air. These organs vary in 

 number, size, situation, and structure, in different species. 



The number of fins varies according to the genera, and 

 even according to the species. It is difficult to fix on those 

 fins which exercise the greatest influence on the habits of 

 the animal, as there is not any one fin common to all fishes, 

 although all fishes have at least one of these organs more 

 or less developed. The size of the fins is equally various 

 in the different species, as it bears no constant proportion 

 to the figure or magnitude of the fish, nor to its habits or 

 instincts. 



The situation of the fins furnishes the ichthyologist with 

 some of the most obvious and useful characters. Those fins 

 which are situate on the back are termed dorsal, and vary 

 greatly in number and shape. The fin which surrounds 

 the extremity of the tail is termed the caudal fin, and is 

 always placed perpendicularly. It is forked in some, even, 

 or rounded in others. Between the caudal fin and the anus, 



