Page:Natural History, Reptiles.djvu/20

12 of truncated mass, "callous in its periphery, on the outside of which one distinguishes only horny cases, a sort of hoofs, which for the most part

correspond with the last phalanges [or joints] they incase, and consequently shew that these animals live only on the land, never in the water."

The feet, as well as the head, are capable of being completely drawn within the bony shell. Some of the species have the hinder part of the carapace flexible, so that it can be brought down to the plastron; while others have the front plates of the plastron jointed to the rest by an actual hinge, so that they can shut up the head as in a sort of box.

The food of the members of this Family consists exclusively of vegetables: their motions are slow and awkward: they live to an immense age, individuals having been ascertained to be above two hundred years old. In temperate climates, they burrow into the earth on the approach of winter, where they remain inert.