2,5? 



quiet shores and fresh waters have but delicate 

 fins, and inconsiderable muscles. The number 

 of the rays is variable, and affords the principal 

 character to distinguish species. The fins and 

 tails furnish the chief organs of motion and pro- 

 gression to fish ; and with their aid they traverse 

 with the greatest rapidity thousands of miles in 

 a season. Large fishes are known to overtake, 

 and play around, with great ease, a ship in full 

 sail ; and it has been calculated that a salmon 

 will glide over eighty-six thousand four hundred 

 feet in an hour, and twenty-four feet in a second, 

 that it will advance more than a degree of the 

 meridian of the earth in a day, and make the 

 tour of the world in a few weeks. 



The fins not only assist the animal in advan- 

 cing, but in rising and sinking, in turning, and 

 even in leaping out of the water. To answer 

 these purposes, the pectoral fins, like oars, serve 

 to push the animal forward ; they likewise ba- 

 lance the head, when it is too large for the body, 

 and prevent it from falling prone to the bottom, 

 as happens to large headed fishes, when their fins 

 are cut off. The ventral fins, which lie flat in 

 the water, in whatever situation the fish may be, 

 serve rather to depress the body, than to assist 

 its progression. The dorsal fin poises the body 

 and preserves the animal's equilibrium, while at 

 the same time it aids its forward motion. The 

 anal fin is designed to maintain the vertical or 

 upright position of the body. Lastly, the tail may 

 be regarded as a rudder, or directing instrument 



