FISHES. 359 



«titution and temperature according to its situation, wc 

 may expect to find the finny tribes that dwell in it, influen- 

 ced by these circumstances. At a very early period, the 

 diversity in the distribution of fishes attracted the attention 

 of observers. Roxdeletius at last attempted a division of 

 this class of animals, from the different situations in which 

 they are found, into marine, fluviatile, lake, and pond fish. 

 It will, however, be more suitable to our present purpose, to 

 consider them as inhabitants of the sea or of fresh-water. 



Tlie salt-water fishes are much more numerous than those 

 which reside in fresh-water. They cannot be distinguish- 

 ed from fresh-water fishes by any peculiarity of structure, 

 or external form. They are always found in the greatest 

 numbers in tideways, and on those banks which are formed 

 at the junction of opposite currents. They in general re- 

 sort to a certain kind of bottom, in which we may suppose 

 they find a plentiful supply of food. Some are always 

 found near rocky shores, while others prefer the sandy bays. 

 Some are found only in the open ocean, and are termed 

 pelagic ; others keep within a short distance from the coast, 

 and are termed litt07'al. 



TheJ'resh-zcate?-Jish£s are not so important, in an econo- 

 mical point of view, as those which inhabit the ocean. Some 

 species frequent rivers, and seem to require, for the preser- 

 vation of their health, a continued current of water. Others 

 live in lakes, and seem contented to spend their days where 

 the water is still. Like salt-water fishes, they appear to 

 prefer particular altitudes ; and in ascending mountains, 

 we may observe that the fish in the lakes and rivers liave 

 their boundaries, as well as the vegetables which cover 

 their surface. Thus, Wahlenberg found, that the pike 

 and perch disappeared from the rivers of the I^apland 

 Alps along with spruce fir, and when 3200 feet below ilie 

 line of perpetual snow. Ascending 200 feet higher, ilu- 



