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GEN. TETRAONYX, Lesson.
Toes five; nails 4-4; sternum solid, broad with six pairs of shields; 25 marginal shields.
TETRAONYX AFFINIS, N. S.
Young. Shell orbicular, its breadth exceeding its length; the back sharply keeled longitudinally, slightly arched, laterally depressed; costal shields with a tubercular nucleus at the posterior margin; greyish green olive, minutely spotted with brown; edge sharply toothed, pale greenish yellow. Sternum truncated in front, angularly indented behind, narrow, yellow; laterally keeled, compressed, pale yellowish green.
HABIT.-Sea off Pinang.
The outline of the shell and its composing shields strikingly resemble the young of Cyclemys orbiculata, Bell.*
The nuchal shield (wanting in one individual,) is small, subrectangular or subtriangular, with the base directed backwards. The vertebral shields are strongly keeled, laterally sloping, hexagonal, broader than long, which however with the first is less the case than with the rest; the second, third and fourth are the broadest, and of nearly equal size; the fifth assumes a broadly truncated triangular shape. The costal shields are nearly all as broad as long; the first, second and third have each a tubercular nucleus in the centre of the posterior margin, the fourth is smooth, and a little smaller than the preceding. The first pair of marginal shields is truncated triangular, the second, and third subrectangular; the fourth sixth, and eighth pentagonal; the rest subrectangular. In all, the posterior external angle forms a more or less sharp spine, directed over the anterior external margin of the next shield. From the first to the sixth the shields gradually increase in size, the sixth being the largest and broadest, from which the following gradually decrease towards the twelfth pair, and their angular spines become obsolete. The sternum consists of two parts: one central, and two lateral, formed by the sternocostal processes of the two central pairs, sharply sloping towards the marginal shields. The central part is longitudinally a little concave, narrowing towards both extremities, truncated in front, angularly in
*SYN. Emys dentata. Illust. Ind. Zoolog.-Emys dhor, Gray.-Emys hasseltii, Boie. -Emys spengleri, Var. Schlegel.-Cistudo diardii, Dum. and Bibr.
dentated behind. The gular pair of shields is very short, broadly subtriangular with the posterior margin concave, curved backwards. The second, and fifth pairs are of nearly equal size, subquadrangular, their external margins forming a sharp ridge. The central part of the third and fourth pairs is subrectangular, broader than long, their margins forming a sharp ridge where they join the sterno-costal processes. The latter are of nearly equal size, longer than broad, their united length being less than one half of the central part of the sternum. The sixth pair is subrhomboidal, longer than broad. The axillary and inguinal pairs are large; the former subrhomboidal or lozeng-shaped, the latter subtriangular. The head is conic; the muzzle short pointed; the vertex irregularly wrinkled. On the temples, cheeks, and round. the orbits, and the lower jaw appear some large polygonal scales. The occiput, angle of the mouth, and the rounded tympanum are covered with similar minute scales. The eyes are large, prominent; the iris silvery grey; the pupil round black. The nostrils are minute, round, horizontally pierced, close together at the apex of the muzzle. The jaws are minutely toothed; the upper has at the symphysis two larger teeth, between which fits a similar single one in the lower jaw, thus hermetically closing the mouth. The neck, the throat and the other soft parts are studded with minute tubercles, except the fore-arm, the posterior tarsal margin, and the back of the fingers and toes, which are covered with broad, but very short, polygonal scales. On the ulnar margin of the fore-arm are four to five large rounded flexible scales. The interdigital web is large and lax. The nails are strong, of nearly equal size, sharp, and arched. The conical tail reaches but little beyond the shell, with a longitudinal furrow behind the vent. The head, neck, throat and the limbs are of the same greyish green olive as the shell. The interdigital membrane is blackish, except the web connecting the fourth and fifth (nailless) toe, which is of a bright greenish yellow colour. Of three individuals observed, differing but little in size, the largest was of the following dimensions:
Two were at different times found in fishing stakes placed along the sea-shore of Pinang; a third was also taken out of the sea with a small hook, baited with a shrimp. The Malays assert that this tortoise also inhabits estuaries and rivers on the Peninsula, and that it grows to a considerable size. The young is very timid, withdrawing the head and extremities when touched, and thus it remained immoveable while a sketch was taken.
From the description of the young of Tetraonyx lessonii, Dum. and Bibr. given in Erpétologie Générale, Tome 2, p. 338, and from the plates of Emys batagur and Emys baska, in Illustr. Ind. Zool., from B. Hamilton's MSS., the present appears to differ in too many particulars, to warrant the conclusion of its being the young of those or that species.* The detailed description of the young will enable future observers, who may succeed in examining the adult, finally to decide the question.
FAM. POTAMIDA, OR RIVER-TORTOISES, Dum. and Bibr. GEN. GYMNOPUS, Dum. and Bibr.
(Trionyx, Geoffroy.-Aspidonectes, Wagler.-Tyrse, Dogania, Chitra,
Shell cartilaginous in its circumference, very broad, flexible behind, and externally not bony; sternum too narrow behind completely to cover the extremities, when the animal withdraws them under the shell. GYMNOPUS GANGETICUS, (Cuvier.)
SYN.-Testudo ocellatus, (Young.)
Testudo chim, (Adult.)
Trionyx gangeticus, Cuvier.
Trionyx hurum, Gray.
Buchan. Ham. MSS.
Trionyx hurum, Illust. Ind. Zool.
Trionyx ocellatus, Illust. Ind. Zool. (Young.)
Trionyx gangeticus, Var, Guerin. (Young.)
Gymnopus ocellatus, Dum. and Bibr. (Young.)
Young.-(Testudo ocellatus, B. Ham. MSS.) Head above pale olive with one large yellow spot between the eyes and a similar behind
* M. M. Duméril and Bibron describe them as two distinct species; Mr. Gray is of opinion that they are identical.
each eye; neck, limbs and posterior margin of the shell dark olive with paler round spots; shell olive with black irregular lines, and 4 or 5 central ocelli, black in the centre, edged with red, round which a black ring; sternum pale whitish-olive.
Testudo hurum, B. Ham, MSS. is the transition state of the former, being about changing the livery. Head yellow olive, with irregular dark lines; shell light olive, vermiculated with blackish or dark olive. The four ocelli are present, but are altered in colours and shape: the centre, instead of being black, is like the rest of the surface, light olive, vermiculated with black; the red ring is changed to black, and the outer black one to light olive. The shape is changed from round to irregular oval.
Adult. (Testudo chim, B. Ham. MSS.) Dark olive-green, vermiculated, and spotted with light olive brown. Beneath greenish white. HABIT.-Malayan Peninsula, Pinang (Rivers and Sea-coast.)
Rivers and Bay of Bengal.
It is of fierce habits, desperately defending itself by biting, emitting when excited a low, hoarse, cackling sound. At Pinang the present species appears to be far less numerous than the two following. The largest individual was of the following dimensions:
Very Young.-Above olive green; the head and upper part of the
neck with numerous small white spots, becoming larger and more
distant on the cheeks and chin; on the vertex, two round black spots; on the occiput two diverging black lines; the shell with several large black white-ringed spots, between which numerous smaller indistinct white spots; margin pale white; several longitudinal ridges, composed of close minute tubercles. Beneath greenish white.
Older.-Above uniformly olive-green; the longitudinal ridges of the shell consisting of tubercles, more distant and proportionally smaller than in the very young.
HABIT.-Malayan Peninsula, Pinang.
Java, Dukhun, "India," "China."
This species is numerous in rivers and ponds. The largest individual observed was of the following dimensions:
SYN.-Testudo chitra, Buchan. Ham. MSS.
Trionyx, indicus, Gray.
Trionyx ægyptiacus, Var. indica, Gray: Ill. Ind. Zool.
Gymnopus lineatus, Duméril and Bibron.
Chitra indica, Gray: Catal.
Shell remarkably depressed, smooth.* Above greenish olive, vermiculated and spotted with brown or rust colour; beneath greenish white. HABIT. Pinang, Malayan Peninsula, (Estuaries, Sea Coast).
Rivers in India, Philippine Islands.
At Pinang this species is frequently taken in the fishing stakes. The Chinese inhabitants greatly relish this as well as the preceding species of Gymnopus, as articles of food. Individuals weighing 240lbs. occur in the Ganges, and others of gigantic dimensions are not uncommon at Pinang. It is very powerful, and of ferocious habits. The largest individual measured :
In the living adult no longitudinal central depression is apparent, nor the outline of the costæ, as represented in the figure in Illustrations of Indian Zoology.