and functions of these extinct families of reptiles; and not only enables us to infer from the restoration of their skeletons, what may have been the external form of their bodies; but instructs us also as to their economy and habits, the nature of their food, and even of their organs of digestion. It further shows their relations to the then existing condition of the world, and to the other forms of organic life with which they were associated.
The remains of these reptiles bear a much greater resemblance to one another, than to those of any animals we discover in deposites preceding or succeeding the secondary series.[1]
The species of fossil Saurians are so numerous, that we can only select a few of the most remarkable among them, for the purpose of exemplifying the prevailing conditions of animal life, at the periods when the dominant class of animated beings were reptiles; attaining, in many cases, a magnitude unknown among the living orders of that class, and which seems to have been peculiar to those middle ages of geological chronology, that were intermediate between the transition and tertiary formations.
During these ages of reptiles, neither the carnivorous nor lacustrine Mammalia of the tertiary periods had begun to appear; but the most formidable occupants, both of land and water, were Crocodiles, and Lizards; of various forms, and often of gigantic stature, fitted to endure the turbulence, and continual convulsions of the unquiet surface of our infant world.
When we see that so large and important a rang has been assigned to reptiles among the former population of
- ↑ The oldest strata in which any reptiles have yet been found are those connected with the magnesian-limestone formation. (Pl. 1, Sec. 16.) The existence of reptiles allied to the Monitor in the cupriferous slate and zechstein of Germany, has long been known. In 1834, two species of reptiles, allied to the Iguana and Monitor, were discovered in the dolomitic conglomerate, on Durdham Down, near Bristol.
