MOVEMENT OF FISHES. 301 



mg an armed front to the enemy, on whatever side he may 

 venture to begin the attack. 



There is a numerous family of fishes, found in tlie seas of 

 India, so constructed as to be able to crawl on land to some 

 distance from the shore. One of these, the Ferca scandens, 

 is even capable of climbing on the trees which grow on the 

 coast* 



If we consider the density of the medium which fishes 

 have to traverse, the velocity with which they move will 

 appear surprising. They dart through the water with ap- 

 parently as much ease and rapidity as a bird flics through 

 the air. Although this may partly be accounted for by the 

 size of their muscles, and the advantageous mode of their in- 

 sertion, yet these advantages would avail but little, were it 

 not for the sudden manner in which their power is exerted. 

 Where the great length and flexibility of the spine tend to 

 impair the force with which the tail strikes the water, the 

 resulting motion is slow and desultory, as is the case with 

 eels, and other fishes of the same elongated construction.! 

 Most fishes, however, move with the utmost rapidity, and 

 with scarcely any visible effort; and perform long journeys 

 without apparent fatigue. The Salmon has been known to 

 travel at the rate of sixteen miles an hour for many days to- 

 gether. Sharks often follow ships across the Atlantic, not 

 only outstripping them in their swiftest sailing, but playing 

 round them on every side, just as if the vessel were at rest. 



* See the account given by Lieutenant Daldorff; Linnean Transactions, III. 

 62. I shall have occasion to notice, in the sequel, the remarkable conforma- 

 tion of the respiratory organs of these and other fishes, which enable them to 

 live, for a time, out of their natural element. 



■J- Carlisle, Phil. Trans, for 1806, p. 9. 



