Genus T r i o n y x , Geoff.
T r i o n y x p e g u e n s i s , Gray. Plates LXX,—LXXIII,
T r io n y x p e g u e n s is , Grray, Suppl. Cat. Shd. Rept., 1870, p. 99, Theobald, Descr. Cat. Rept., Brit.-
Ind. (Calcutta), 1876, p. 81.
I s o la p eg u en s is , Gray, Proc. Zool. Soc., 1873, p. 81.
The specimens of Trionyx collected by Mr. Theobald in Pegu and Arracan,
and which found their way to the British Museum, were ihree in number, as far as
I have been able to make out by an inspection of the registers in which they
are entered and of the specimens themselves. There is a young Trionyx in
alcohol, the type of T. formosus,1 and the skull of which was afterwards extracted;
the skull of the type of T. phayrei,2 the shelly of which was presented
by Theobald to the Bristol Museum3; and the head of an adult in spirit,4 the type
of T. peguensis, and the skull of which was afterwards figured under the name of
Isola peguensis.
Theobald mentions that only two skulls of Trionyx (exclusive of young animals
in spirit) passed from his hands into the British Museum, either by gift or purchase,
“ a head of T. stellatus,” and second, “ the skull of my type of T. phayrei.” This
is confirmed by the Hand List of Shield Reptiles.
The history of these specimens is noteworthy. The young ariima.1 in alcohol
was described in 1869 as T. formosus,5 and in 1872 as Nilsonia formosa,6 but
at this latter date Hr. Gray contrasts the skull of the young animal which had
been removed from the specimen, with an adult skull which he received from
C. Palconer, Esq.,7 one of the executors of the late Dr. Hugh Ealconer. This adult
skull has been since figured,8 and we are thus enabled to judge of its true nature.
After a careful consideration of the figure, I do not hesitate to pronounce it to be
the skull of a Gangetic species, viz., T. hurv/rn,9 distinguished from T. Gangeticus by
its antero-posteriorly long symphysis without a median ridge, and to be the skull of
the fresh-water turtle which has been described under the names of T. sewaare,10
T. ocellatus11 and T. buchanani,12 all of which yield similar skulls, quite distinct
from the young skull of T. formosus. The skull of T. phayrei was first apparently
I Hand L ist Shd. Rept., B . M., 1873 p. 77. .
I I o., p. 80.
3 Ohs. on Ind. and Bunn. Trionyx, Theobald, Cal. 1873, p. 8.
* Hand List Shd. Rept., p. 80.
5 Proc. ZooL Soc., 1869, p. 217, Plate xv, fig. 1; Suppl. Cat.'Shd. Rept., 1870, p. 99.
6 Ann. and Mag. Nat. Hist*, vol. x, p. 332, 4th Ser., 1872.
1 1 . p. 332.
8 Proc. Zool. Soc., 1873, p. 46, fig. 2.
9 Syn. Rept., 1831, p. 47, Tab. x ; 111. Ind. Zool. vol. ii, 1833,1 .16.
10 Gray, Ann. and Mag. Nat. Hist., vol. x, 1872, p. 336 ; Proc. Zool. Soc., 1873, p. 50: Theobald, Proc. As. Soc..
Bengal, 1875, p. 172. *
11 Ann. and Mag. Nat. Hist., voL x. 1872, p. 337; Proc. Zool. Soc., 1873, p. 51; Theobald, Proc. As. Soc., Bengal,
1875, p. 174.
“ Proc. As. Soc., Bengal, 1874, p.. 78.
referred by Gray to T. formosus,1 as he states under T. formosus that “ this
may be the species indicated as a Trionyx phayrei,” but afterwards2 he identified
the skull of T. phayrei with T. hivriim of his Synopsis Reptilium, but with which
T. phayrei has no affinity. In 187131 identified a skull, recognized by Theobald
to be the skull of his T. phayrei, with the type skull, T. jeudi, and I stated
.that after a comparison of the two, I could not detect any characters by which to
separate them, but Dr. Gray considered that I had erred, and that the turtle I described
as T. phayrei was distinct from T. jeudi and referable to his T. per ocellatus. But,
as we have seen, Dr. Gray after this still identified T. phayrei with T. hu/rum.
But in the Hand List4 my view of the identity of T. phayrei and T. jeudi was
ultimately accepted, but the species was erroneously referred to the T. sewaa/re,
which is identical with the T. hu/rum of the Syn. Reptilium.
The head in alcohol which was the only specimen of the kind in the British
Museum obtained from Theobald has a peculiar history. In the Suppl. to the Oat.
Shield- Rept.6 the head of an adult animal in spirit is stated, under Trionyx jeudi,
to have been obtained from Mr. Theobald, who procured it in Pegu, but it is
remarked that the symphysial ridge of the lower jaw is only slightly raised and very
different from the type of T. jeudi. On the following page, a head in spirit , from
Mr. Theobald is again mentioned, and described as the type of T. peguensis.
There can be no doubt but that this also is the head referred to under T. jeudi.
The skull of this head was ultimately removed and figured by Dr. Gray,8 and the
prepared skull shows a large injury which is explained by Theobald, who states that
the two Trionyces he collected in Pegu were shot by his revolver.7 The specimen
which constituted, the type of T. peguensis, Theobald mentions8 was taken by
a fish hook from the Sittang river at Tonghoo, but as both specimens were shot
by him, we conclude that this example was shot after it had been landed by the
hook.
I shall now consider these specimens in detail, and some other Trionyces which
have since been figured and described by Theobald,9 in order to arrive at an understanding
of their relations to the species figured in this work. I have not seen the
shell of the type of T. phayrei which was obtained by Theobald in a mountain stream
in the Arracan range, west of Pegu, but it was remarkable owing to the circumstance
£hat the roughened surfaces which generally occur on the elements of the plastron
of Trionyces were almost absent, the granulations being only slightly developed.
Theobald did not describe the coloration of his type, beyond stating that the
colour during life was dark dull brown, handsomely lined as in Telochelys cantori;
1 Proo; Zool. Soc., 1869, p. 219, et. Suppl. Cat. Sh. Rept., 1870, p. 98. '
2 Ann. and Mag. N a t . Hist., x, 1872, p. 336.
8 Proo. Zool. Soc., 1871, p. 154.
4 t. c., p. 80.
6 I. c., p. 98.
5 Proo. Zool. Soc., 1873, p. 52, fig. 5.
7 Proc. As. Soc., Bengal, 1874, p. 85.
8 Obs. on Ind. and Bnrm. Trionyces, Cal., 1873, p. 7-
* L c., Proc. As, Soc., Bengal, 1874; I . c., 1875,