72 CRETACEOUS ERA. 



tants of the sea, except the cetacea, have been found in the 

 cretaceous formation zoophytes, radiaria, mollusks, crus- 

 tacea (in great variety of species), and fishes in smaller 

 variety. Down to this period, the placoid and ganoid fishes 

 had, as far as we have evidence, flourished alone ; now they 

 decline, and we begin to find in their place fishes of two 

 orders of superior organization, those which predominate in 

 the present creation. These are osseous in internal structure, 

 with corneous scales. The enaliosaurians disappear in this 

 formation, while the land reptiles, so numerous in the two 

 preceding periods, become much diminished in numbers. Of 

 the latter, one of the most remarkable was the mosaesaurus, 

 which seems to have held an intermediate place between the 

 monitor and iguana, and to have been about twenty-five feet 

 long, with a tail calculated to assist it powerfully in swim- 

 ming. 



Fuci abounded in the cretaceous seas, and confervas are 

 found enclosed in flints. Of terrestrial vegetation, as of ter- 

 restrial" animals, the specimens in the European area are com- 

 paratively rare, rendering it probable that there was little dry 

 land near. The remains are chiefly of ferns, conifers, and 

 cycadese, but in the two former cases we have only cones and 

 leaves. There have been discovered many pieces of wood 

 containing holes drilled by the teredo, and thus showing that 

 they had been long drifted about in the ocean before being 

 entombed at the bottom. 



The series in America corresponding to this, entitled the 

 Ferruginous Sand formation, presents fossils generally iden- 

 tical with those of Europe, not excepting the fragments of 

 drilled wood ; showing that, in this, as in earlier ages, there 

 was a parity of conditions for animal life over a vast tract of 

 the earth's surface. To European reptiles, the American 

 formation adds a gigantic one, styled the Saurodon, from the 

 lizard-like character of its teeth. 



We have seen that footsteps of birds have been announced 

 from America, in the new red sandstone. Some similar 

 isolated phenomena occur in the subsequent formations. In 



