86 On D-GBOLO PAETI 



, riatwrbis. etc., may often l>c found below the 

 grassy surface of a flat meadow. Such a layer as certainly 

 demonstrates that the meadow was once a lake, as if we 

 had documentary evidence to prove that such had 

 the condition of the place within the last few generations. 

 (3) Corals and other zoophytes, mollusca of such genera 

 as Lingula, Cyprina, Buainutn, and Rissoa, likewise fishes 

 of such types as the ray and shark, point to marine con- 

 ditions of life. The conclusion that any particular stratum 

 must have been laid down on the sea-floor might not be 

 warranted were it made to rest on merely a single fossil. 

 Shells and Crustacea, for instance, are often carried in- 

 land by sea-birds, and their remains may be left there to 

 be covered up together with those of terrestrial animals. 

 But when the whole character or fades of the fossils of a 

 rock is of a marine type, we may confidently infer that 

 the rock was deposited on the bed of the sea. Certain 

 forms of life have had a remarkable persistence in the 

 ocean. Some of the living brachiopods, for example, 

 are closely similar to those even of very early geological 

 periods. These persistent forms, though they do not 

 absolutely prove, yet give strong grounds for believing 

 that, as they are all marine forms now, so they must have 

 been marine from the beginning. And when they are 

 found associated with other forms belonging to recognis- 

 able marine types, the inference cannot be resisted 



3. Terrestrial Move ments. The importance of organic 

 remains as witnesses of movements of the earth's crust 

 depends upon the limitation of organisms to their 

 own conditions of existence. A group of living sea- 

 shells cannot be found in an inland lake, nor will a 



