410 ON THE GEOLOGICAL RELATIONS 



are generally found in the more recent strata, and 

 commonly under peculiar circumstances formerly ex- 

 plained. Rocks of undisputed marine origin do not 

 often contain amphibious animals, nor do these abound 

 anywhere. There are however tortoises in the chalk, 

 and animals of the Lizard tribe in the Lias ; itself an 

 amphibious deposit, as I shall hereafter suggest ; at 

 least where it contains snch remains. 



Thus does this race connect the marine and the 

 terrestrial organic fossils of an animal nature. Among 

 the latter, the lithophytes are rare ; and if milleporae 

 occur in the coal strata, the inferior beds of this are 

 amphibious. Testaceous animals are found in the 

 fresh water strata, just as in the marine ones ; but 

 they are more limited in variety and quantity, and the 

 rocks themselves belong either to the coal series or 

 the tertiary deposits ; otherwise than under trans- 

 portation, and in the amphibious lias. Fishes are 

 also found in the same strata ; and I have formerly 

 pointed out the sources of confusion and error on 

 this subject. 



The fossil remains of terrene animals form a large 

 class, in variety, if not in numbers ; presenting also 

 a peculiar interest, by approximating the existing 

 earth with its last preceding condition. If we extend 

 the rule so as to consider every buried animal as a 

 geological organic fossil, they preserve the chain un- 

 broken. By transportation, they occur in marine 

 strata ; and they also exist in lacustral ones and in 

 alluvia. Former chapters have explained much that 

 I need not here repeat on this subject ; and it only re- 

 mains to add, that they are sometimes found in modern 

 rocks, produced like Travertine, or from fragments. 

 The remains themselves comprise quadrupeds, birds, 

 reptiles, and insects, to which I may again add amphibia. 



