Owen has formed two orders[66] for the reception of some remarkable extinct reptiles of this age, found especially in South Africa and India, but also in Europe and America. The first includes large lizard-like animals having horny jaws like those of turtles, and in some of the species with great defensive tusks (Fig. 144). Their mode of life is not well known, but they may have been peaceable and harmless vegetable feeders. The second has been already referred to, in connection with the Permian, where it first appears, though it is continued in the Trias (Fig. 145). The resemblance of the skulls of these creatures to those of Carnivorous mammals is very striking, and nothing can be more singular than their early appearance and their decadence before the advent of those Tertiary mammals which in more modern times occupy their place. [Illustration: FIG. 143.—Skeleton of _Clidastes_. A great Mososauroid Sea Reptile of the Cretaceous.—After Cope, much reduced.] [Illustration: FIG. 144.—An Anomodont Reptile of the Trias (_Dicynodon lacerticeps_, Owen). Reduced.] [Illustration: FIG. 145.—A Theriodont Reptile of the Trias (_Lycosaurus_).—After Owen. Reduced.] [Illustration: FIG. 146.—Skeleton of _Pterodochylus crassirostris_. Jurassic of Solenhofen. Reduced.] [Illustration: FIG. 147.—Restoration of _Rhamphorhyncus Bucklandi_. Jurassic of England.—After Phillips. _a_, One of the teeth. Natural size.] Perhaps the most extraordinary of all the Mesozoic modifications of the reptilian type was that of the flying reptiles, or _Pterodactyls_. These were, in short, lizards modified for flight, somewhat in the same manner with the bats among the mammals. If the bat may be likened to a flying shrew-mouse, a Pterodactyl may in like manner be compared to a flying lizard; but the modification in the latter case is by much the more remarkable, inasmuch as the lizard is a cold-blooded animal, and far less likely to be endowed with the active circulation and muscular power necessary to flight than is the mouse. In point of fact, there can be no doubt that the Pterodactyls must have been provided with some approach to a mammalian or ornithic heart, as they certainly were with great breast-muscles attached to a keel in the breast-bone for working their large membranous wings. These wings were also somewhat original in their construction. They were not furnished with pinions, like those of the bird, but with a membrane like that of the bat, and this, instead of being stretched over four enormously lengthened fingers, as in that quadruped, was supported on a single elongated finger, corresponding, singularly enough, to the little finger, which usually inconspicuous member constituted in some of these strange creatures a limb longer than the whole body (Figs. 146, 147.) The other fingers of the hand were left free for walking or grasping. They are thus believed to have been able to walk as well as to fly, and even in case of need, to swim; while