OF FISH IN GENERAL. 



Utility of the fins. 



ventral fins are placed towards the lower part of 

 the body, under the belly, and serve chiefly to 

 raise or depress the fish in the water. The dor- 

 sal tins are situate on the ridge of the back, and 

 are very large in flat fish: their use, like the pec- 

 toral ones, is to keep the body in equilibrio, as 

 well as to contribute to its progressive motion. 

 The anal fins are placed between the vent and 

 the tail, enabling the fish to keep an upright 

 position. 



In some the fins are much more numerous 

 than in others; a fish completely fitted for swim- 

 ming with rapidity .is generally furnished with 

 two pair on the sides, and three single ones, two 

 above and one below; yet it does not always 

 happen that the fish which has the greatest num- 

 ber of fins is the swiftest swimmer. The shark 

 is thought to be one of the swiftest, and yet has 

 no fins on his belly, while the haddock seems 

 more completely fitted for motion, and yet is 

 not near so swift a swimmer. 



By means of their fins, the bodies of the fish 

 are duly poised: were these fins cut oft', the 

 fish can still swim, but will turn upon its sides or 

 its back, without being able to keep itself in an 

 erect posture as before. When the fish is in a 

 state of repose, it spreads all its fins, and seems 

 to rest upon the pectoral ones, or those near the 

 gills, and the ventral, or belly fins, near the bot- 

 tom ; it has the power of folding up its pectoral 

 fins, and by that means inclining to the side on 



