314 FISHES. 



CHAPTEK XXII. 



FiEST Class of Veetebeata. 



Fishes. 



MoEE than two-thirds of the surface "of our globe 

 is covered by the sea : continents and islands are 

 everywhere intersected by rivers, and overspread 

 with lakes and ponds, thus presenting an aggregate 

 of waters so considerable as far to exceed the dry 

 land in extent, and affording space for the existence 

 of animated beings, by no means inferior, in number 

 or variety of species, to those which inhabit the 

 earth. 



At first sight, we might suppose that the watery 

 element afforded little diversity, and that the various 

 races of fishes could as well inhabit one locality as 

 another. The sea, however, in different latitudes 

 offers great differences of temperature, especially in 

 the vicinity of coasts, some of which, exposed to the 

 full influence of a burning sun, reflect intolerable 

 heat, whilst others, covered with snow, regions of ice 

 and frost, exhibit a perpetual winter. Vast lakes 

 are raised to considerable elevations, and from their 

 glacier-barred sides the rivers stream with icy cold- 

 ness. The rivers and the lakes are all fresh water, 

 light and pure ; the seas are salt, and thus of greater 

 density ; some waters are clear and limpid, others 

 are agitated by continual currents, whirled in cascades, 

 or hurried on in ceaseless torrents: the crystal 

 fountain, and the muddy marsh, and all the shades 

 of difference between these extremes, present so 

 many climates, all of which require creatures of 

 different habits and endowed with different faculties. 

 We need, therefore, be no longer astonished at the 

 infinite variety in the forms and endowments of the 

 finny tribes, or surprised that some of them are of 

 shapes that to our ignorance appear monstrous and 



