112 ORGANIC REMAINS. 



plants ; of marine and fresh- water shells, Crustacea, and fishes ; and of 

 aquatic and terrestrial reptiles, mammalia, and birds. This simple state- 

 ment furnishes ground for most interesting deductions respecting the 

 ancient condition of the globe. We cannot, indeed, determine what was 

 the comparative extent of its seas, lakes, and dry land, but we may form 

 very reasonable opinions concerning its temperature, and a tolerable 

 history of its inhabitants at different periods. For as the order of suc- 

 cessive position among the rocks is likewise that of their relative an- 

 tiquity, the fossils collected from these rocks may be arranged in chrono- 

 logical order. 



The fossils of Britain thus arranged, (according to the example 

 of Mr. W. Smith,) present us with many curious and important re- 

 sults. The following instances are selected rather to shew the rich- 

 ness and beauty of the subject, than to include all that is known 

 respecting it. 



The organic reliquiae of animals are more ancient than those of plants, 

 for they lie in the slate rocks of Cornwall and North Wales, whilst no 

 plants have yet been found in any rock older than the lower red 

 sandstone. The most abundant fossil remains of plants belong to ter- 

 restrial tribes ; but the animal reliquiae are mostly of aquatic origin ; 

 and very few examples are known of any bones of terrestrial animals 

 occurring in strata more ancient than those above the chalk. 



The most ancient animal remains are those of bivalve shells, (spiri- 

 ferae,) such as are not known to exist at present. The most ancient 

 fossil plants which appear in the lower carboniferous rocks, almost 

 wholly belong to terrestrial genera of the natural monocotyledonous 

 orders, filices, lycopodiaceae, and equisetaceee, and, by their analogy to 

 existing tropical tribes, seem to demonstrate that the climate of these 

 northern regions was then warmer than it is at present. 



The fossil plants of the middle sera, which accompany the lias and 

 oolitic rocks in Yorkshire and Sutherland, belong chiefly to the natural 



