99 



nishes as we descend, until, in the lowest part of the eighth 

 region, the number of Testacea was found to be only eight, in- 

 dicating a zero in the distribution of animal life at probably 

 about 300 fathoms. 



" In the upper regions the more southern forms prevailed, 

 whilst those of the lower zones presented a northern character, 

 indicating a probable law, that in the distribution of marine 

 animals regions of depth are equivalent to parallels of latitude. 



ec .Anj oscillations of level, however slight, would produce 

 alternations of strata containing distinct groups of organic beings 

 with others void of such ; and partial alternations of marine and 

 freshwater beds would be formed, a phenomenon now in progress 

 on the coasts of Asia Minor. All this would occur without con- 

 vulsions or violent catastrophes of any kind. Changes of level, 

 however slight, might cause the extinction of whole genera of 

 animals and plants, of which only such as hard parts would be 

 preserved. Were the present sea-bottom of the iEgean to be 

 upheaved, whole classes of animals would disappear and leave 

 not a trace behind to assure the future geologist of their having 

 existed *" 



With respect to fishes, it is probable that every basin of the 

 ocean has its particular tribes ; while indeed the regions which 

 some inhabit are well known. The most remarkable species of 

 fish are met with in the torrid zone and its vicinity. Here the 

 lizard tribe, under the various names of crocodiles, gavials, 

 alligators, and bavilla, attain to an immense growth; but each 

 variety, although within the same zone, is confined to particular 

 regions, as the crocodile of the Nile and the alligator of the 

 Orinoco. 



When we consider terrestrial animals, but more especially 

 those that are wild, we may divide the earth into a number of 

 zoological regions or provinces, each of which, in the same in- 

 dividual zone, is the residence of a distinct set. The first of 

 these provinces, if we commence from the north, is the arctic 

 region, which contains the white bear, the rein deer, the arctic 

 fox, and other tribes common to both of the great continents. 

 The northern temperate zone is divided by the ocean into two 

 great districts. The same tribes are found to be spread from 



* Athenaeum, No. 830. 



H 2 



