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Mexican Mud Turtle
Colouration.—Like the majority of the species the upper shell is dull olive or brown, the shields narrowly bordered with black. The plastron is pale yellow, with clouded brown markings at the edges of the shields.
Dimensions.—The measurements given are of an adult specimen (male) from Sinola, west coast of Mexico:
Distribution.—Mexico, generally in slow-running streams and rivers.
Distribution.—Eastern North America.
Distribution.—United States, west of the Mississippi and Ohio Rivers.
Distribution.—Southeastern United States.
Distribution.—States bordering the Mississippi--to Illinois.
Distribution.—Georgia, northern Alabama and Tennessee.
Distribution.—Illinois to the Gulf States and eastward.
Distribution.—New York to Ohio; southward to Florida.
Distribution.—Texas.
Distribution.—Central States--Illinois to Texas.
Distribution.—North Carolina to Georgia.
Distribution.—Lower California.
Distribution.—Alabama.
Distribution.—Southern portions of the Gulf States.
Distribution.—Georgia and Florida.
Although this species does not occur in the United States, it ranges well into the northern portion of Mexico. Its description is given as representing the type of the tropical species of this genus.
The lobes of the plastron are very wide and when closed against the upper shell, form such a perfect union that it is difficult to insert a straw between any portion. The general effect of the under surface is quite different than with the species considered except C. henrici, as the bridge of the plastron is very flat--in fact, it cannot be termed a bridge, for the entire surface of the under shell is flush with the edge of the carapace. The characteristic notch at the rear of the plastron, is but feebly represented.
This species has a large head and strong jaws. The tail of male specimens terminates in a nail-like spine.
The head is dull yellow, speckled or marbled with black.
Length of Carapace . . . . . 6 inches.
Width of Carapace . . . . . 3 7/8 inches.
Length of Plastron . . . . . 5 1/2 inches.
Width of Front Lobe, at Hinge . . . . . 2 3/4 inches.
Width of Rear Lobe, at Hinge . . . . . 2 1/2 inches.
Width of Head . . . . . 1 1/8 inches.
THE GENERA CHRYSEMYS, MALACOCLEMMYS AND CHELOPUS
A Group of Aquatic Chelonians Known Commonly as Pond Turtles and River Turtles. They are Characterised by Their Broad, Flat Shell. Most of the Species are Edible
THE term "Terrapin" is a convenient one, for under this appropriate, popular head we may group all of the North American "turtles," or semi-aquatic chelonians, except the Soft-shelled Turtles (Trionychidae), the Snapping Turtles (Chelydridae) and the Musk Turtles (Cinosternidae).
Classification of the Terrapins.--The Terrapins are embraced in the large family Testudinidae; three genera are represented in North America. The largest genus is Chrysemys; it contains the largest species and its members range over the United States generally, though most of them inhabit the southeastern portion; others occur in Mexico, Central America, South America and the West Indies. Malacoclemmys is a small genus, confined to the central and eastern portions of the United States. Chelopus is also a small genus and the species occur only in the United States.
The Terrapins frequent the borders of ponds, brooks and rivers--some, the salt marshes of the eastern coast. They are characterised by their broad, flattened shell--quite smooth with the majority of them. The hind feet are extensively webbed; all of these animals are excellent swimmers. Many of the species of Chrysemys have very long, sharp claws on both pair of feet.
Of all the Terrapins, the "Diamond-back," (Malacoclemmys palustris), is the most familiar, as it is a favourite though costly article of food and a by-word of the eastern markets. The larger species of Chrysemys and several of those belonging to Malacoclemmys are sold in large numbers, but always at a far less price than the Diamond-back. The former turtles, often seen in large numbers in the markets where they are kept in cold vats to prevent them losing fat, are known commercially and collectively as "Sliders." Large examples sell at $1.50 to $2.00, while considerably smaller Diamond-backs--about eight inches long--are worth fully $60.00 a dozen. The species of Chelopus are worthless for market purposes.
Definition of the Genera
A. Size moderate to large. 6 to 14 inches.
Shell broad and flattened, with some species rising to a very blunt apex. No concentric grooves on shields, but numerous parallel furrows, extending lengthwise on many of the species. Claws very long.
Genus Chrysemys.
Shell flattened, but rising in the centre to rather a sharp apex, surmounted by a strongly-defined keel. Shields smooth, or with concentric grooves.
Genus Malacoclemmys.
B. Size smaller--from 3 to 8 inches.
Shell low and bluntly rounded. Smooth or with concentric rings.
Genus Chelopus.