84 
ORGANIC REMAINS. 
plants ; of marine and fresli- 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. F or 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 marine animals are, perhaps, 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 rocks so low in the 
slate series. 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 and in the transition 
rocks, almost wholly belong to terrestrial' genera of the natural mono- 
cotyledonous orders, Alices, 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 asra, which accompany the lias and 
oolitic rocks in Yorkshire and Sutherland, belong chiefly to the natural 
