The sternum has the gular transversely truncated, the post-gular considerably
broader than the preanal portion of the young female, and the anal notch broad and
its margins obtuse. The sternal ridges, which are posteriorly convergent, are marked
by an areolar nodosity on the posterior margin of the pectorals and abdominals. In
the adult female, the post-gular region is narrower than the preanal, and the axillary
and inguinal diameters are nearly equal. In the male, the characters of the young
female prevail, and the axillary is broader than the inguinal breadth. The ridge
all but disappears in the adult female, and in the male it is feeble. The gulars
are generally shorter than the post-gulars which are always less than the pectorals.
The abdominals are the largest of all the sternal shields, and the preanals are
invariably larger than the post-gulars, and occasionally as long, or longer, than the
pectorals. In young specimens, the anal suture is sometimes not so long as the
posterior margin of an anal, while, in the adult, it is longer than the breadth of
the anal notch.
In some individuals the sternum is projected more forwards than in others,
being nearly in a line with the anterior margin of the carapace, while in others it
is much further back.
The following table gives the measurements of the carapace and sternum
in eleven females and three males, the sexes of which were ascertained by dissection
irt—
Measurements of living specimens of Batagur thurgL
9 9 9 9 9 9 9 9 9 9 3 $ 3
'in / In. In.. In. In. g pE s/ In. In. In. In. In. Tn. -Tn. Tn.
Length of carapace,
straight line 19-07 18-76 18-26 18-00 18-00 18-58 17-00 17-43 16-75 16-26 1633 6-17 603 5-83
Breadth o f carapace
over curve 18-00 16-42 16-75 16-67 PPPP 17-00 17-00 13-33 15-92 15-26 15-50 6-26 6-17 5-78
Length o f sternum . 1826 17-9C 16-5C 163; 16-26 17-0C 16-26 ®6-42 15'5C 15-75 14*83 5-75 5-5( 5-26
Breadth at axilla 7-0C 6-75 6-0f 6-Ot 6-26 6-26 617 5'75 5-75 5-5C 5-75 2-3f 2-22
„ at groin . 676 6-75 6-26 6-5C 6-67 6-5i 6-0( 6-26 6-00 5-75 6-5S 2-17 2-15 2-00
Depth through mid--
dle o f third vertebral
8-00 7-00 7-17 7-38 7-17 7-26 7-17 6-92 7-00 6-42 . 6-67 2-83 2 75 2-67
Out of thirty living examples of this species, of all ages and sizes, only three
were males, the largest being only 6"T7 in the length of its carapace, whilst the-largest
female measured as much as 19'07 inches, in a straight line. I cannot say whether
the remarkable discrepancy between the sizes of the two sexes indicated in this table
is persistent, but this I can state, that the shells of these small males are fully consolidated,
and that the penis was so enormously developed that it measured one-half of
the length of the carapace. The males are distinguished by the more elongately oval
character of their shells, which are not so high as those of the female, and by their
longer tails, and these three characters serve at once to distinguish them from the
opposite sex. The rarity of the male sex is also worthy of note.
A few small yellowish tubercles on the upper surfaces of the toes of the fore
foot, with the exception of the first; and a triangular scaly surface crossing the limb
from the outer margin of the elbow to the dorsum of the first toe; the hinder margin
of the limb, having a row of six or seven large membranous plates. On the under
surface of the limb, a patch of medium-sized scales occurs in the fold of the wnTrlfl
joint, and smaller scales on the sole of the foot. A few enlarged scales on the
upper surface of the hind toes, and along the hinder margin of the limb, on
which they confer a serrated border. The tail is covered above with rather spiny
tubercles.
Shell dart brown above, with an orange margin, a blact vertebral line and
a dart spot over the areolse of the three first costals, sometimes a continuous line.
/Under surface yellow, each plate occupied with a dart brown centre, so that the
yellow is almost marginal.' Head dart brown. An orange band above the snout,
between the eyes and through the eyelid. A narrower orange-yellow band from
the posterior angle of the- eye and over the tympanum on to the sides of the
neot, where it fades. A yellow band from the anterior angle of the eye forwards,
below the nostrils, to the opposite side, the band being separated from the one
above it by a narrow dark brown band passing through the nostrils. A yellow spot
below the eye. A yellow band from the exterior of the base of the symphysial
hook of the lower jaw along the ramus of the latter and below the tympanum,
to the sides of the neck. A dark band infernal to this, the under surface of the
throat being mottled with dark brownish and yellowish. A very obscure yellowish
band from the anterior margin of the tympanum backwards. Iambs olive brownish
above, margined with yellowish. Claws dark brown. Tail with a yellow dorsal
line. In the adult, the bright colours are fainter than in the young. In some
males there is an orange line along the lower margins of the second, third and
fourth costals, and which I have not observed in the females.
The leading characters by which this skull is separated from other Batagurs
are the absence of any upturning of the nose; the deep notch on the alveolar
margins of the premaxillaries, external to which is a strong triangular serrated toothlike
process; the strong dentation of the alveolar border of the maxillary; and still
stronger toothed character of the lower jaw, which has a large symphysial sharp tooth,
fitting in to the notch in the upper jaw and the absence of a coronoid. The internal
nares are broad, and shorter than in other Batagws, but this character would be of no
sub-generio value were it not associated with a differently formed external wall. In
true Batagws, the palatine and pterygoid form an expanded surfece at the posterior
angle of the maxillary palate, producing a well-defined external wall to the internal
nares by the sharp border of the palatine. The latter is pierced by the palatine
canal, on the same plane with the general surface of the palate, whereas, in B. thwgi,
there is no expanded pterygo-palatine surface, the pterygoid arching outwards and
anteriorly to the posterior angle of the maxillary palate, there being no ridge-like
border to the palatine, which is wholly concave and pierced in the outer wall of the
nares by its canal.