FISHES. 317 



fins of fishes, and found, in consequence, that all the mo- 

 tions were unsteady, that they reeled from right to left, 

 and up and down, in a very irregular manner. The dor- 

 sal and anal fins serve to maintain the body in its vertical 

 position. But from the circumstance of some of these fins 

 being wanting, and others evidently too small to produce 

 the desired effects, those fins which are present, appear to 

 be capable of executing all the movements for which the 

 others, when present, are designed. 



The medium in which fishes reside, prevent us from 

 making any accurate observations on the velocity of their 

 motion. Mackrel, and some other marine fishes, will seize 

 a bait moving at the rate of six or eight miles an hour ; 

 and some of die voracious sharks will keep up with a ves- 

 sel in her voyage across the Atlantic. The darting of a 

 salmon or trout in the water, resembles the rapidity of an 

 arrow, but such motion cannot" 1 be kept up for any length 

 of time. This the angler is well aware of, who, with his 

 hook fixed on very slender gut, will kill, by fatigue, the 

 strongest salmon in the course of an hour or two, and a 

 large trout in the course of two or three minutes. These 

 facts seem to indicate, that however numerous and power- 

 ful the muscles of a fish may be, they are incapable of sup- 

 porting a continued exertion. 



Besides the action of swimming, fishes are likewise capa- 

 ble of leaping. They accomplish this by a violent effort 

 of the caudal fin, or, according to some, by bending the 

 body strongly, and afterwards unbending it with an elastic 

 spring. 



A few species are capable of sustaining themselves in the 

 air for a short interval, and are termed Flying-fish. Such 

 fish have the air-bag, an organ to be noticed hereafter, of 

 uncommonly large dimensions ; hence the body has great 

 buoyancy. The pectoral fins are likewise of an extraordi- 



