conforms more to the Emys type than to that of Oeoemyda, and the skulls, in the
presence of a quadrato-jugal, agree with Emys.
There is nothing in the features of the internal anatomy of these forms that
would entitle us to separate them from the Emydes. They are all provided with
cloacal bladders, hut to a varying degree. In G. grmdis the bladders are very large,
and the whole of their inner surfaces are covered with dendritic papillae. In
G. depressa they are small, and also in 0. theobaldi, hut I am unable to speak of
these structures in C. tricarmata, having never had the opportunity to examine a
fresh example of that species. In the genus Emys they are large and generally
smooth,
The presence of cloacal bladders indicates that all of these animals have one
habit, and in this respect they must be regarded as belonging to the Emydidce, and
the males, as in the Emydes, have a more or less concave sternum, but these
structures are not present in the so-called genus Manouria nor in the Testudmidce
generally.
In Geoemyda grandis the toes of the fore feet are webbed to the base of the
claws, but not broadly so, and the hind toes are hardly perceptibly webbed, while in
G. depressa the web, at the base of the toes, in the hind foot, is still more obscure.
In Emys both feet are webbed, but the even partial webbing in these two forms
referred to Geoemyda, serves to connect them with Emys.
In Chaibassia tricarmata the toes seem to have been in much the same condition
as in O', theobaldi, in which no web can be said to exist.
As there can hardly now be any doubt regarding the natural family to which
these four species rightly belong, the question arises what Value is to be attached
to the absence in the skulls of G. grmdis and G. depressa of 'a quadrato-jugal
bone. Besides this feature, which separates the latter from the true Emydes, their
skulls, although conforming in their alveolar palatine characters and large palatine
foramina to the Emyde type, differ from it in the great breadth of the fronto-nasal
region. But viewing their structure as a whole, they appear to me to be entitled to
generic rank among the EmydidtB.
The Emyde which Mr. Theobald has placed in the new sub-genus Chaibassia
subordinate to Geoemyda should, by the structure of its skull, be more properly
considered as sub-generic to the genus Emys, because its whole form above and
below, its more elongated character generally, and the presence of a quadrato-jugal,
show it to be closely allied to Emys, indeed so much so, that, judging by the skull
alone, one would not be justified in separating it generically from Emys. There is,
however, a feature observable in Blyth’s type of C. tricarmata, and in another of
the same species which I procured from Chota Nagpur, through the valued assistance
of Colonel Dalton, C.S.I., which would seem to indicate a tendency in this.form to
diverge towards the members of the family Cistudinidce. I t is this, that the process
from the hypostemal piece which springs upward and abuts against the first costal
and third marginal plates, does not become firmly attached to the latter, but is
movable on it, and this false joint involves apparently the side of the hyposternal, but
does not extend forward to the hyostemal. This is observable in the male type of
C. tricarmata, Blyth, and in a female of the same species from Chota Nagpur, and
it is distinctly visible in the alcoholic female type of Chaibassia theobaldi, but no trace
of it is visible in the male example in alcohol. Had this character been persistent
in both sexes of C. theobaldi, I should not have had any hesitation in regarding
Chaibassia as a distinct generic form, occupying a position intermediate between
the box tortoises and the Emydes. I t is an Emyde in all its other features, except
its feet, which being unwebbed, and the hind foot rather club-shaped indicate an
affinity towards the land tortoises, with which, however, it has no alliance by its
skull, nor by its cloacal bladders, nor indeed by the characters of its visceral cavity
and soft parts, which are also those of an Emyde. I t must therefore remain
with the Emydes, but it is entitled among them to generic rank on account of its
divers affinities.
I t is interesting to observe that C. theobaldi in its shell and in. the type of its
colouring considerably resembles Cuora. I t is also worthy of remark that although
the transverse suture between the hyo- and hypostemal pieces is not mobile, it
is yet very prominently seen through the epidermic plates.
+ G e o e m y d a d e p r e s s a , Andr. Plates LY, LVI, and LXXY B, figs. 1 to 5.
Geoemyda depressa, Andr., Ann. and Mag. Nat. Hist., 4th ser., vol. xvi, Oct. 1875, p. 284.
Geoemyda cvrakana, Theobald, Descr. Cat. Kept., Brit. Ind., 1876, p. 7.
Shell elongated, much depressed, the depression increasing from before backwards,
the shell being somewhat expanded across the inguinal region; vertebral
region (2 and 3) nearly flat. Anterior border broad and slightly concave; posterior
border, behind inguinal area, expanded, and with a strongly serrated margin;
vertebrals with a low ridge in adults. Interval between the first costal and anterior
marginals concave, also the interval between the fourth costal and its marginals
which are reverted. The sides of the middle of the shell, (second and third
costals,) considerably convex; anal notch moderately deep; nuchal and gulars well
developed; anterior border transverse.
Shell above light brown, with a blackish tinge on the external border of the
marginals. Sternum rather clear yellow, the interval between the axillary and
inguinal notches deep black; the outer halves of the pectoral and anal plates being
blackish-brown, with a partial reticulation extending across the plates; the gulars,
postgulars, and anals have also a tendency to be coarsely and irregularly reticulated
with the same colour.
Head of animal rather small; upper and lower jaws deep, and area below the
nostrils slightly convex. Limbs large, especially the hind legs; claws strong and
webs not well developed. The anterior aspect of the lower part of the fore leg
covered with large imbricate scales, and smaller scales on the dorsum of the foot, a
large scale being at the base of each claw. Hind limb covered with small scales,
but with a line of enlarged scales along its posterior margin. Tail moderately long
and covered with rounded scales. The neck-skin loose and covered with minute
t 4