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Tortoises Turtles

water, species, families, fresh, found, sea-turtles, entirely, nostrils and carapace

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TURTLES, TORTOISES and TERRA PINS, members of the reptilian order Testudi nata or Chelonia (q.v.). To all of the marine and some of the fresh-water species, espe cially those of large size, the name °turtle)) is applied; most of the smaller pond and marsh dwellers are a few being designated as c'terrapins,D while the terrestrial ones, whatever their size, are properly ((land tortoises?' About 300 living species, most of them inhabitants of fresh waters, have been described, but the group has steadily declined since Eocene times, and many ancient families are entirely unrepresented in the modern fauna. Tortoises are especially numerous in warm climates, and none extend into the Arctic regions. The marine forms are pelagic and wide-ranging. The various members of this group exhibit considerable diversity in habits and structure, and have been arranged (see CHELONIA) in four sub-orders and numerous families, of which three sub-orders and seven families are represented in the North American fauna.

Of the sub-order Athece and family Der matochelydiche the huge leather-turtle (q.v.), the largest of all modern turtles, occasionally appears on our coast. The Trionycholidea with the single family Trionychide, or soft-shelled turtles, are found in the fresh waters of Africa, Asia and North America. They have the plastron and carapace incomplete and covered by a leathery skin; the neck is very long and flexible, and though folding vertically cannot be retracted entirely within the shell; the head is small and elongated with a slender snout, at the tip of which are the nostrils; the feet are broadly webbed, with long straight claws on some of the toes. Amyda mutica has the upper jaw serrate and the carapace without tubercles. It is found in the region of the Great Lakes and the Ohio River. Aspidonectes spinifer has the cutting edge of the upper jaw smooth and the margin of the carapace with tubercles. It is abundant throughout the upper Mississippi Valley and particularly in the slug gish streams emptying into the Great Lakes. Closely related species are found southward. The soft-shell turtles are strictly aquatic, leav ing the water habitually only in the spring, when about 50 spherical hard-shelled white eggs are deposited in an excavation above the level of the water. They spend much time buried in the mud at the bottom, either entirely concealed or with the head protruding from a hole. They breathe by raising the nostrils to the surface, or, if in water too deep, by means of a thick growth of vascular papilke in the pharynx over which a current of fresh water from the nostrils continually passes. Strictly carnivorous, they feed upon all kinds of fish, frogs, mussels, snails and insects which come within reach of their ravenous jaws and which they seize with remarkable suddenness.

They are powerful swimmers.

The order Pleurodira includes three families of recent and several of extinct turtles, the for mer being confined to the fresh waters of South America, Africa and Australia. The tartaruga of the Amazon is of great commercial importance. Unlike most turtles of this group they are said to be largely vegetarian, which probably accounts for the great value placed upon their flesh and fats. During the months of September and October vast numbers leave the water at about midnight to deposit their eggs in holes on the higher ground. Two re lated genera are found in Africa. The family Chelydidcr is confined to South America and Australia. The matamata (Chelys matamata) is common in Cayenne. Its length when fully grown is about three feet. It is remarkable in many ways; its snout is prolonged as in Aspido nectes and the head and neck are covered with tufts of cutaneous outgrowths which probably assist in the concealment of the animal in the thick aquatic vegetation among which it lives. It is carnivorous.

To the Cryptodira belong the great ma jority of living turtles and tortoises. This sub order includes 10 or 12 families, seven of which have recent representatives. The Cheloniide includes the sea-turtles, in which the limbs are flat, scaly, inflexible paddles and the heads quite incapable of retraction within the shell. Only four genera and about seven species are known, all widely distributed. The three Atlantic species all occur on our shores more or less frequently. The best-known one is the green turtle, whose flesh is so highly esteemed in soups, etc. This species (Chelone midas) is the largest of sea-turtles, and reaches in some cases a weight exceeding 1,000 pounds. It occurs in all parts of the world when the water is not very cold, but most numerously about tropical archipelagoes. As with the other large sea-turtles, the most numerous catch is made when the females come on shore at egg-laying time, on moonlight nights in summer. Their retreat is cut off and the turtle turned on its back. When once in this position these turtles are unable to right themselves. They can en dure many weeks without food and water, and hence can be transported great distances on seas in the hold of ships. Before the days of refrigerated meat they served as a welcome diet for sailors; and on some of the Pacific islands these and other large turtles were wholly exterminated by reckless slaughter. The green turtles feed on the roots of the eel-grass, and, betrayed by the floating tops of the grass, are sometimes taken in nets while feeding. The principal catch for the American market is now made in the neighborhood of the Florida reefs, where it forms a regular business with many boatmen. Their catch is largely made by spearing.

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