Page:Geology and Mineralogy considered with reference to Natural Theology, 1837, volume 1.djvu/197

 Rh had been called into existence, the important office of controlling the excessive increase of the aquatic herbivore appears to have been consigned to the Crocodiles, whose habits fitted them, in a peculiar degree, for such a service. Thus, the past history of the Crocodilean tribe presents another example of the well regulated workings of a consistent plan in the economy of animated nature, under which each individual, whilst following its own instinct, and pursuing its own good, is instrumental in promoting the general welfare of the whole family of its contemporaries.

Cuvier observes, that the presence of Crocodilean reptiles, which are usually inhabitants of fresh water, in various beds, loaded with the remains of other reptiles and shells that are decidedly marine, and the further fact of their being, in many cases, accompanied by freshwater Tortoises, shows that there must have existed dry land, watered by rivers, in the early periods when these strata were deposited, and long before the formation of the lacustrine tertiary strata of the neighbourhood of Paris. The living species of the Crocodile family are twelve in number, namely, one Giaval, eight true Crocodiles, and three Alligators. There are also many fossil species: no less than six of these have been made out by Cuvier, and several others, from the secondary and tertiary formations in England remain to be described.