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Berlandier's Tortoise
Colouration.—Dull brown, the centres of the shields yellowish though this character becomes obscure with age. The plastron is dull yellow. The fleshy parts of this tortoise, particularly the hind limbs, are paler than with the two preceding species.
Dimensions.—The measurements are of a rather small specimen, from Brownsville, Texas:
Distribution.—Southern Texas and northeastern Mexico.
Habits.—Much like the preceding species.
Structure.—From all of the other chelonians the Soft-shelled Turtles are strikingly distinct. The shell is exceedingly flat and in its outline is either bluntly oval or almost circular. Lacking the hard shields of other turtles, the carapace and the plastron are soft and leathery: the former bends freely at the edges, and droops, like a flap, over the orifice through which the head and neck are withdrawn in time of danger.
Distribution.—Georgia to Florida; westward to Louisiana.
Distribution.—Central and northern tributaries of the Mississippi and St. Lawrence Rivers.
Distribution.—Similar to T. spinifer.
Distribution.—Tributaries of the Rio Grande River.
This species is very distinct from the two preceding ones, owing to its very broad and high carapace, which produces a very globular aspect. While the upper jaw of the two former species is notched, this tortoise has a book on the upper mandible.
The shell is nearly as broad as long and is proportionately high and globular. Compared with the preceding species the forelimbs are narrower and the head smaller. The front lobe of the plastron, which in front extends beyond the margin of the upper shell, terminates in a narrower, deeply notched process and is but slightly directed upward.
Length of Carapace . . . . . 6 inches.
Width of Carapace . . . . . 5 3/8 inches.
Height of Carapace . . . . . 3 1/4 inches.
Length of Plastron . . . . . 6 1/4 inches.
Width of Plastron . . . . . 4 3/4 inches.
Width of Forearm . . . . . 7/8 inches.
Width of Head . . . . . 1 1/4 inches.
As the writer looks back upon his general experience with living reptiles of all the orders, he considers the various species of tortoises that have come under his observation to have displayed the most marked symptoms of intelligence. Among all reptiles they are the most docile, and even with the huge species from the Galapagos Islands and their allies from the Aldabra Islands, which creatures have power enough in their great jaws to sever a man's hand at the wrist, we find the same docility, combined with an intellect that approaches the mental capacity of warm-blooded creatures.
Strongly Characteristic Chelonians, with a Soft, Leathery Shell
Classification.--The family Trionychidoe is composed of about twenty-seven species embraced within six genera. A few species inhabit North America; the majority occur in southern Asia and the East Indies; several species inhabit Africa. The largest genus is Trionyx. All of the North American species belong to this genus; the other species inhabit both Asia and Africa.
The neck of the Soft-shelled Turtle is very long, the head is narrow and the snout is provided with a slender proboscis, at once imparting a characteristic aspect. While the general appearance of these creatures is fleshy and inoffensive, and the jaws are provided with lip-like folds of skin, the latter cover powerful and keen-edged mandibles and these reptiles bite with the energy of the snapping turtles. The head and neck are completely retractile. As the species are very aquatic, the feet are broad and extensively webbed.
General Habits.--All of the Soft-shelled Turtles inhabit rivers, ponds and lakes with a soft, muddy bottom. They seldom or never leave the water unless to deposit their eggs--a short distance above the water side. These reptiles frequently take the hooks of fishermen. They are uniformly agile and vicious; large individuals are dangerous.
In the areas inhabited by these turtles in the United States, they are commonly called the "flap-jack turtles." The title is a harsh one, but it conveys the right impression of their structure, as removed from the water they present a ludicrous impression of large and animated pancakes. Their progress under such conditions is clumsy and the soft plastron becomes bruised and lacerated on a hard, rough surface.
A key to the North American species is given:(Two alleged species are excluded. These are Trionyx asper and T. nuchalis, both of Agassiz. The range of the former has been given as "The Mississippi"--the latter as occurring in the Cumberland and the Tennessee Rivers. The writer has been unable to examine specimens of either and is not convinced as to their standing as full species. Both appear to be related to T. mutica.)
A. Front margin of carapace with conical tubercles.