Animals. 221 



pectoral fins, are placed at some distance 

 behind the opening of the gills ; and are 

 generally strong and large ; answering 

 the same purpose, to a fish, as wings do 

 to a bird in the air ; namely, pushing 

 the body forward, like the oars to a boat. 

 They also serve to balance the body of 

 the fish, and prevent the head from sink- 

 ing, which it would otherwise do. The 

 ventral fins are placed under the belly, 

 towards the lower part of the body ; 

 these are always extended flat on the 

 water, in all situations ; and serve to 

 raise or depress the body of the animal, 

 rather than assist his progression. The 

 dorsal fin, is situated along the ridge of 

 the back ; and serves to keep the fish in 

 equilibrium, and also assists it in its velo- 

 city. This fin is very large, in all the 

 flat fish ; the pectoral fins of which are 

 proportionally less. The anal fin, ex- 

 tends from the anus to the tail, and serves 

 to keep the body of the animal upright, 

 or in a vertical direction. In some fish- 

 es, as before observed, the tail is hori- 

 zontal, and in others perpendicular. - 

 Thus equipped, these animals have the 

 xiiost rapid motions ; and perform voy- 

 T 



