262 VARIETY IN FORMS OF FISHES. 



Fishes people the ocean with their shoals, and serve to 

 keep in check the innumerable creatures of still lower con- 

 struction, while they themselves are held in check, and af- 

 ford sustenance to millions which have been placed in our 

 system above them. In form they are the most varied be- 

 ings in creation, and the most inventive fancy could scarcely 

 imagine a shape or appearance to which a resemblance would 

 not be found. They are of hideous or loathsome bulk or the 

 most graceful form, and of gorgeous and resplendent colors ; 

 all wondrously adapted to the diiFerent modes of obtaining 

 their food, whether by stealth or deceit, strength or swift- 

 ness. The general form of a fish is admirably adapted to 

 its native element. In all fishes which require swiftness to 

 secure their prey, the tail is the great organ of motion. The 

 absence of any neck gives the advantage of a more exten- 

 sive and resisting attachment of the head to the body, the 

 greater proportion of which is left free for the play of the 

 muscular masses which move the tail. Besides serving as 

 the rudder or paddle, it is the tail of the fish that enables 

 many of them to make those leaps out of the water to which 

 we have frequently alluded to in theso pages. From the 

 enormous whales and sharks to the small stickleback, this 

 power seems to belong to the greater number of fishes. 



They?7is on the upper surface of the fish serve to balance 

 the body; those on the lower surface to turn it, to move it 

 slowly, and to keep it suspended in strong currents ; but in 

 all these movements the assistance of the tail is observable. 



Some of the fins of fishes are vertical, constituting a kind 

 of keel or rudder. They differ in number, size, and the na- 

 ture of the rays which support them, being sometimes spiny, 

 and in other cases soft and articulated. Those correspond- 

 ing to arms or wings are the pectorals (the chest), invariably 

 fixed behind the gills. 



Pal^, in his " Natural Theology," thus sums up the actions 

 of the fins of fishes : '* The pectoral, and more particularly 



