Page:Natural History, Reptiles.djvu/19

Rh terrestrial species are believed to subsist exclusively on vegetable diet; the marine species add to this the flesh of large shelled mollusks; the marsh and fresh-water kinds prey on fishes, young birds, insects, worms, and any other animals they can overcome.

About one hundred and twenty species are known to belong to the Order, of which twenty-eight are terrestrial, eighty-four are fluviatile, and eight are marine. They are confined to the warmer regions of the earth; none of them being properly inhabitants of the British Islands; but occasional occurrences of some of the marine species on our shores are recorded, and a terrestrial Tortoise is imported in some numbers from the south of Europe, and kept as a pet in gardens.

We shall consider the Tortoises as comprised in five Families; Testudinidæ, Emydidæ, Trionychidæ, Sphargidæ, and Cheloniadæ.

In this Family the carapace is very high and convex, solid in structure, and covered with a horny shell. The general form may be illustrated by the common Greek Tortoise (Testudo Græca), familiar to most of our readers. But the principal and most remarkable peculiarity, and that which most perfectly indicates the manner of life common to the group, is the conformation of the limbs: the feet are short and stumpy, nearly of equal length, with toes scarcely distinct, immovable, united by a thick skin, and forming a sort