Page:A Treatise on Geology, volume 1.djvu/108

 92 families of reptiles, and especially ophidia, are the least common in a fossil state. The greater number of reptiles found in the various formations belong to tribes which now contain many aquatic species. But they were not all destined to live in water. There are fresh water batrachians in the brown coal deposits on the Rhine, and the quarries of Oeningen; land batrachians (labyrinthodon) in the new red sandstones, and aquatic batrachians (?) in the old red sandstone of Elgin (Mantell); land tortoises have been traced in the new red sandstone of Scotland, and the oolite of Stonesfield; fresh water turtles in the London clay of Sheppey, the Purbeck beds, Kimmeridge clay, and new red sandstone; marine turtles in the London clay, chalk, greensands, and oolites, perhaps even in the Silurians of Canada; land lizards in the wealden and oolites; aquatic lizards, and crocodilians in many tertiary and secondary strata; and, finally, the bones of flying lizards have been detected in the lias, oolite, chalk, and London clay.

In his instructive Reports on British Fossil Reptiles , professor Owen has divided the most numerous group of fossil reptiles—the Saurians,—into five sub-orders, viz. enaliosauria, or sea lizards; crocodilia, analogous to gavials, crocodiles, and alligators; dinosauria, or monstrous land lizards; lacertilia, analogous to the smaller lacertæ; and pterosauria, winged lizards.

Among enaliosauria, we have sixteen species of plesiosaurus, ten of ichthyosaurus, and two of pliosaurus, distributed through the lias and oolitic formations, and ceasing in the cretaceous deposits. Crocodilia are represented by eight genera,—viz. crocodiles, suchosaurus, goniopholis, teleosaurus, steneosaurus, poikilopleuron, streptospondylus, and cetiosaurus, which include fourteen species found in the lias, oolites, wealden and tertiary beds.

The dinosauria are formed by three genera, ,