Page:Natural History, Reptiles.djvu/245

Rh residence in the water, and with a digestive apparatus, fitted exclusively for the assimilation of vegetable food, assuming by degrees the function of atmospheric respiration, acquiring limbs which are formed for leaping on land with great strength and agility, and manifesting the most voracious carnivorous appetite, will not only excite feelings of the deepest admiration, but necessarily lead to the investigation of the laws by which such extraordinary changes are governed, and of the relations which they bear to the theory of continuous affinity before alluded to, and to that of progressive development through the whole of the animal kingdom. That such phenomena are exhibited by the typical forms of this Class, will be sufficiently established by the slight sketch of their structure, habits, and development, which will presently be offered.”

The Amphibia are arranged by the eminent zoologist just quoted in five Orders, distinguished by the general form, the presence and number of the limbs, and the character of the respiration. They are named Anoura, Urodela, Amphispneusta, Abranchia, and Apoda.