Family II. Emydidæ.
(Marsh Tortoises.)
This is the most numerous in species of the Families of the Testudinata. MM. Duméril and Bibron observe, that America produces more Marsh Tortoises than all the rest of the world put together; for of the seventy-four species composing this family, forty-six are confined to that continent. The cause of this disproportion they attribute to the vast body of water in the form of immense lakes, marshes, and rivers with which the expanse of America is intersected. The continent of Africa, on the other hand, which offers in this respect so great a contrast to the former, presents us with but three species of Emydidæ, but is very rich in Testudinidæ.
The Marsh Tortoises, or Terrapins, have the body much flatter, the carapace being less arched, than the Land Tortoises. The toes are separated, or rather separately moveable, and are furnished with hooked claws; they are usually connected by a palmated membrane or web, and the hind feet are larger than the fore ones. They have twelve plates on the plastron; they withdraw the head and neck between the shields.
The habits of this Family differ much from those of other Tortoises. They swim with facility, and walk on land with a less slothful gait than the Testudinidæ. They inhabit marshes, stagnant ponds, lakes, and even small rivers whose course is gentle; feeding on small water-animals, such as frogs and newts, the young of web-footed fowl,
