Tortoise, the popular name of the chelo-nian reptiles whose habits are wholly or' in part terrestrial and fluviatile, including all the testudinata except the marine species or turtles - that is, the amydoe of Oppel as distinguished from his chelonii. Their general characters have been given under Testudinata. The suborder amydoe, according to Prof. Agassiz, comprises the following seven. families, not equally related to each other : trionychidoe or soft tortoises, chelyoidoe (the matamata), hy-draspididce, chelydroidte or snappers, cinoster-noidon or mud tortoises, emydoidoe or terrapins, and testudinina or land tortoises. Of the very numerous species here included, space will permit the mention of only a few of the typical forms in the above order of families. Du-meril and Bibron divide the amydoe, according to habitat, into chersites or land tortoises, corresponding to testudinina, and elodites or marsh tortoises, including all the other families except the trionychidoe, which form theirpota-mites or river tortoises. Though some pass nearly all their life in the water, none are entirely aquatic, and none can swim unsupported for great distances; when in the water, they usually remain at the bottom, and seldom swim freely except when alarmed or seeking to leave it.
Their locomotion is a kind of walking, the weight being about equally distributed on the front and hind limbs, which have nearly the same development, the motions of each pair alternating with each other. The shield or carapace is more symmetrical than in the turtles; the feet are always distinct from the legs, and movable upon them; the toes are cither separate and short, or united by a web capable of expansion and contraction; the limbs can generally be withdrawn under the carapace, and the head wholly or partially. The tortoises rank higher in the order than the turtles. - In the trionychidoe the carapace is flat, thin, and oval, and very incomplete, the ribs united only on the median line, and extending thence to the margin like spokes of a wheel; it is covered with a tough skin, flexible on the margins; neck long and flexible; head pointed, and terminating in a long leathery snout; jaws covered with a horny sheath, and the lips fleshy; feet short, broad, and strong, five-toed and fully-webbed, three of the toes with claws; limbs only partially retractile and moving horizontally; skin loose and free about the neck and limbs.
The oldest geological deposit in which any of this family has been discovered is the greensand of New Jersey. They are active species, preferring the muddy bottom of shallow water, sometimes lying concealed in the mud with only a part of the head exposed, taking breath from time to time by stretching up their long neck and raising the tip of the snout above the surface; they can remain under water more than half an hour at a time, rarely going on land, where their movements are awkward; in the water they move rapidly, striking suddenly at objects by means of their long neck; they prey principally on fish, seizing also frogs, small birds, and young alligators and lizards; the species found in the Nile is very destructive to Young croco-diles; they have been known to attack persons bathing. They are very wary, but are frequently caught on hooks baited with a live fish; their flesh is highly esteemed. Their eggs are numerous, spherical, and very brittle; they are deposited on sandy shores near the water in April and May, and the young appear in July. The genus trionyx (Wagler), equivalent to cryptopus (Dum. and Bibr.), is peculiar to Asia and Africa, the species of this country formerly referred to it belonging to the genera aspidonectes (Wagler), platypeltis (Fitz.), and amyda (Ag.). The common soft-shelled tortoise of the northern states (A. spinifer, Ag.) attains a length of 14 in.; it is yellowish brown, beneath white, mottled, streaked, and dotted with black; a blunt keel along the median line slopes uniformly to the sides, and the anterior margin is furnished with spines; it is found from Lake Champlain to Pennsylvania'and west to the Missouri and Mississippi rivers; its flesh is very delicate.
Other species are found in the southwestern states. Very large species of this family were brought here from western equatorial Africa by Mr. Du Chaillu. - The chelyoidoe somewhat resemble the preceding family, but the head and neck are more retractile and furnished with numerous membranous fringes and lobes of singular form. There is only the single genus chelys (Dum.), and a single species, the matamata (C. matamata, Dum.), attaining a length of 2 or 3 ft.; it inhabits the stagnant waters of tropical South America, feeding on fish; it is captured for its excellent flesh. - The hydraspididce, containing the genera platemys, podornemys, etc., were united to the chelyoids by J. E. Gray, the two forming the elodites pleuroderes of Dumeril and Bibron. The neck is long, the head retractile or bent laterallv under the shield; in some the skull presents the union of the temporal and parietal bones to form a broad roof over the temporal region, as in marine turtles, combining thus the family characters of the two suborders. Prof. Agassiz thinks that po-docnemys will be found to agree more closely with the earlier geological types than with any other, and that the group of pleuroderes bears the same relation to other testudinates that the marsupials do to ordinary mammals.
The sexual differences are so great that they have been mistaken for specific; the tail of the male is much the longer, and in this sex there are sharp asperities between the joints of the hind legs; the colors are also different. This group is foreign to the United States, and mostly South American, a few being found in Africa and Madagascar. - The chelydroidoe, described in the article Snapping Turtle, are thoroughly aquatic, and the lowest of the amydce except the preceding families; they are characterized by their keeled back, serrated margin, broad, flat, and imperfectly retractile head, narrow and cross-like sternum, and large tail. - The cinosternoidoe have a long and narrow body, the carapace rising to behind the middle, and thence descending steeply backward; the whole shield is ossified, covered with large horny scales, and as wide behind as in front, with a tendency of the edges to round up and turn inward; the tail is neither long nor strong enough to bear any of the weight of the body, and in the male ends in a horny nail; legs slender, feet short and round, toes freely movable and webbed, and the whole very flexible; head long behind and short in front of the eyes, pointed, with the small mouth underneath; alveolar ridge sharp, the lower jaw ending in a point; neck long and slender; the plastron is sometimes hinged.
In average size they are the smallest of the order, the least being about 4 in. and the largest 9 in. in length; all are American, and no trace of their fossil existence has been discovered; the sexes are very different. They live mostly in water and in the mud, coming out to bask in the sun in places where they can readily drop into the water at the approach of danger; their food is principally animal, and their motions quick, though feeble and awkward; generally timid, they bite fiercely if attacked while feeding, like the insectiv-ora among mammals. The colors are generally dark, sometimes with reddish, greenish, and yellowish tints. They lay three to five eggs, on the shore near the water, in holes dug with their hind feet; they are elongated, with a smooth and shining surface, thick, and brittle. In the common mud tortoise ((thy-rosternum Pennsyfoanicum, Ag.), the jaws are strong and cutting, and the mouth long and narrow; it is dusky brown above, yellowish dusky or brownish below; chin and throat dirty yellow, with the warts on the latter brighter; it is usually about 3½ in. long, nearly 3 in. wide, and I¾ in. high.
It is found from Pennsylvania to Florida, and west to the Mississippi valley; the anterior and posterior parts of the sternum are movable on the central piece; it abounds in muddy ponds, feeding on small fish and aquatic insects and larvae; it is a pest to anglers, seizing the bait set for better game; it has a slight odor of musk, but less so than the musk tortoise (ozotheca odorata, Ag.), which ranges from New England to Florida, and west to the Mississippi. - The emydoidoe are most numerous in species, over 00 being described, presenting great differences in size, structure, and habits. The body is ovate, swelling in the centre, the margin with a tendency to spread outward; the carapace is completely ossified and united by sutures, high and irregularly convex in all directions; plastron long and broad, and sometimes hinged; the jaws horny, without lips, and not terminating in long sharp points; head, neck, and limbs completely retractile; nostrils at the end of the snout, which is not prolonged into a proboscis; toes long and webbed, or short and free, according as the habits are .aquatic or terrestrial; skin of head, neck, limbs, and tail more or less scaly.
They are principally aquatic, though some are terrestrial, the limbs moving horizontally while swimming, and walking being performed on the whole foot (as in plantigrades); they are generally of moderate size, the smallest being 4 in. and the largest (the aquatic) 15 in. in length. The food is both animal and vegetable, consisting of fish, worms, larvae, berries, leaves, and grass; they are most abundant in warm regions. The eggs are laid in holes dug by their hind legs, the terrestrial species laying 2 to 7, and the aquatic 10 to more than 30; the shell is less calcareous and more flexible than is usual; the shape is oblong. Though this family is most numerous in North America, there is not a single species described under the genus emys by herpetologists which belongs in it; the so-called cistudo Blandingii, corresponding to the emys of Europe, is the only representative here of Brongniart's genus; the others belong to various genera as established by Agassiz in vol. i. of his "Contributions to the Natural History of the United States" (1857). The genera trachemys (Ag.), ptychemys (Ag.), deirochelys (Ag.), and malacoclcmmys (Gray) have been described under Terrapin. The common painted tortoise (chrysemys picta, Gray) may be known by the yellow borders of the black dorsal scales, the blood-red blotches and lines on the marginal plates, limbs, and under part of tail, and the golden yellow sternum.
It is found as far north as New Brunswick, through the eastern and middle states to South Carolina and Georgia; west of the Ohio it is replaced by the C. marginata (Ag.); it is about 6 in. long, 4½ in. wide, and 2½ in. high; it is most abundant in ditches and sluggish waters, spending most of the day basking in the sun; it is very timid, hibernates early, and is one of the first to appear in spring; it feeds on insects, worms, tadpoles, etc, and is very troublesome to anglers; it will survive only a few days out of the water. The speckled or spotted tortoise (nanemys guttata, Ag.) is another very common species, distinguished by its yellow dots on a black ground, and its blackish sternum bordered with yellow. It is found from New England to the Carolinas, east of the Alleghanies; it often comes on land, to feed on worms and orthopterous insects; it is about 5 in. long, 3 in. wide, and 1¾ in. high. The geographic tortoise (graptemys geographica, Ag.) is so called from the network of reddish brown lines spread irregularly over the dark brown carapace, somewhat resembling the outlines of countries on a map.
It is one of the most active and bold of the family, and is found from New York and Pennsylvania to Michigan, Tennessee, and Arkansas; it is over 8 in. long, 6 in wide, and 3 in. high, with a tail of 2½ in. The sculptured tortoise (glyptemys insculpta, Ag.) is very common in the northern states as far south as New Jersey; the carapace is reddish brown, each scale with radiating yellow ridges, often smoothed down in old specimens; marginal plates and sternum yellow, each with a black spot at the posterior angle, and generally with concentric stria); limbs brick-dust color below; it is 8 in. long, 5 in. broad, and about 3 in. high, with a tail of over 2 in.; it passes long periods away from water. Blanding's tortoise (emys melea-gris, Ag.) is the only true species of the genus here; it is black above with numerous yellow spots, sometimes arranged in lines; below dusky yellow, each plate with a largo quadrangular dark spot at the outer and posterior angle. It is found from New England westward to Wisconsin, being most abundant on the prairies, and very terrestrial in its habits; it is 8 in. long, 5½ in. wide, and 3 in. high, with a tail of 2¾ in.
The box or checkered tortoise (cistudo Virginea, Ag.; C. clausa and Carolina of other authors) has a rough and strong shell, generally of a light brownish color with very numerous bright yellow blotches and lines, more or less radiating, giving somewhat the appearance of tortoise shell; sternum usually yellowish with dark blotches; hind feet plantigrade; plastron with a hinge in the middle, so that the anterior and posterior portion can each be brought in contact with the carapace, and enclose the animal in a perfect box. It is about 6½ in. long, 4½ in. wide, and 2¾ in. high; it is found from New England south to the Carolinas, and west to Michigan; it is entirely terrestrial, and a very poor swimmer; it is common in the pine barrens of the southern states, where it is called cooter and pine terrapin by the negroes; it feeds on insects and succulent plants, and is easily domesticated. - In the testudinina or land tortoises the carapace is entirely ossified, very convex in the middle region, but well balanced; the plastron is broad, flat, and solid; openings for protrusion of limbs.small and narrow; head, limbs, and tail completely retractile within the shell, and the plastron in some with movable lobes; head small and shielded, nose broad, and eyes far apart; alveolar margin with a sharp edge, and the jaws fitting closely by ridges and furrows; skin everywhere more or less scaly; toes mostly concealed under the skin, as far as the last joints, which are free and covered by flat sharp nails, usually live anterior and four posterior; feot short, stout, and somewhat clubbed; the great intestine is longer and the lungs are larger than in any other testudinate, in relation with the greater convexity of the shell.
They are most abundant in warm climates, and are the largest of the order, the great Galapagos tortoise being 3 to 4 ft. long, the African coui (psammobates radiatus, Fitz.) 1½ ft., the gopher 1 ft., and the common European land tortoise 8 in. (the smallest of the family). Here also belongs the fossil gigantic colossochelys Atlas (Cautl. and Falc), from the Sivalik hills, which must have measured nearly 18 ft. in length; it is found with the great extinct ungulates which it so much resembled in gait and habits. There are no tortoises indigenous to the British islands, though they might easily be naturalized there. Agassiz places all the American testudinina in the genus ocerobates. They live entirely on land, and when put into water walk on the bottom; the body is raised on the last joint of the toes, and the gait is firmer, more steady, and less slow than in any other tortoise. Their food consists of succulent plants and fleshy fruits. There are only eight genera, but many species. The gopher tortoise (testudo polypliemus, Daudin) is about 15 in. long, and has a nearly flat shell, the plates marked with concentric striae disappearing in old age; the plastron is thick and firm, projecting beyond the carapace in front, and deeply emarginate behind; the head is short, thick, and obtuse, covered with plates; the eyes are large, with a dark iris; the jaws covered with horny, serrated plates; the neck short, and its skin granulated; the fore limbs very large and thick, compressed antero-pos-teriorly, with five fingers armed with strong nails; along the outer edge of the forearm is a row of projecting horny points; the hind limbs are short, thick, rounded, with four toes armed with strong nails.
The general color is brownish yellow, with darker brown tints, the head almost black, the lower parts dirty yellow, and the limbs dusky. It is found in Florida, Alabama, and Georgia, but does not appear to go north of the Savannah river. Like the rodent gophers, they burrow in the ground, preferring such dry and sandy places as the pine barrens, where they exist in troops; they live entirely on vegetable food; they are fond of basking in the sun, though they cannot bear its full summer heat, and cannot endure rain; they become torpid in winter. The adults are very strong, moving with a weight of 200 lbs. and the females are the largest; the flesh and the eggs are esteemed as food. In the European land tortoise (testudo Groeca, Linn.) the carapace is oval, somewhat widest and gibbous behind, marbled with black and yellow; plastron pale yellow with a wide blackish band down each side; legs short, and tail ending in a horny tip. It is found in Spain, Italy, Greece, and other countries bordering on the Mediterranean; in England it has been domesticated and known to live more than a century.
The Galapagos tortoise (mega-lochelys Indica, Fitz.; testudo elephantopus, Harlan) is the largest of the order, frequently measuring 12 ft. in circumference; the shell is very convex and of a deep brown color. It is very fond of water, drinking large quantities, and delighting to wallow in the mud like a pachyderm; some live in the mountains and others in the low lands of the Galapagos islands, and the latter in their journeys after water in the elevated regions have worn well beaten paths, which led mariners to the discovery of the springs, often at a great distance from the shore; they drink by immersing the head up to the eyes, and swallowing great mouthfuls, about 10 a minute, according to Darwin; their flesh is excellent and largely used both fresh and salted, and a very clear oil is made from the fat. They feed on succulent plants and vegetables, and in captivity are fond of cabbage, lettuce, and marrows. They were formerly very numerous in these islands, and probably live for centuries. Their gait is very slow, about two miles in 24 hours, though they have been known to travel four miles in the same time.
The eggs are laid in October in the sand, and are about 8 in. in circumference; the young are devoured by birds of prey; in Great Britain, where numbers have been kept alive, they go under ground in November and reappear in the middle of April; many have been seen in the United States. - The tortoise shell of commerce is the product of the hawk's bill or imbricated turtle. (See Tuetle).
Shell of the Painted Tortoise (Chrysemys picta).
Shell of Speckled Tortoise (Nanemys guttata).
Sculptured Tortoise (Glyptemys insculpta).
Shell of Box Tortoise (Cistudo Virginea).