As in T. monticola, the sub-caudals of this species have some of their number
entire.
This species does not appear to be so arboreal in its habits as some of the others.
Stoliczka obtained it on the limestone hills near Moulmein, and Theobald records
that he found a single specimen in the caves near the same locality. The larger
of the two specimens I procured, I encountered on the limestone rocks, below the
Yethaycoo pagoda, in the second defile of the Irawady, lying coiled up on the
ground, ready to strike.
T r im er e st t r t js m o n t íc o l a , Günther. Plate LXXVI, f i g s . 4 & 5 .
Parias mandata, Gray, Ann. and Mag. Nat. Hist., vol. xii, 1858, p. 892.
Trimeresurvs monticola, Günther, Rept. Brit. Ind., 1864, -p. 888, pl. xxiv, B. ; Theobald, Journ.
As. Soc., Bengal, vol. xxxvii, 1868, ex No., p. 76; id., Descr. Cat. Sept., Brit. Ind.,
1876, p. 220; Anderson, Proc. Zool. Soc., 1871, p. 194; Fayrer, Thanat. of India, 1872,
' pi. xv.
In the valley of Hotha, this species is not at all uncommon, and I obtained
four examples of different ages. .Two of these specimens, unlike the types of
the species and the other examples from Western Yunnan, have the second labial
distinct from the plate in front of the facial pit. In the T. mutabilis, Stoliczka,
the second upper labial may either form the front of the facial pit, or it may occasionally
be divided in two. A similar variation occurs in the Trimeresurus referred
by Stoliczka1 to T. andersoni. This variation, however, as far as my observations go,
would appear to be a rare occurrence, because in the extensive series of Trimeresuri
in the British Museum, I have failed to detect a single instance in which the second
labial when it forms the front of the facial pit is completely divided, or an example
in which the second labial, when it does not enter into the facial pit, unites
with the shield that does. In one individual, however, of T. a/namallensis,
the second labial shows a tendency to division on one side. The occasional division,
however, of the second labial into a facial pit-shield in T. montícola and
in T. mutabilis introduces another ¿lement of difficulty in determining what
are really reliable specific characters, so far as the Trimeresuri are concerned ;
for those characters, which, in other snakes, are generally guides to the species
by reason of their stability, are obscured in the Trimeresuri by their variability
.T
he scales in these Yunnan specimens which are all from one locality, viz., the
outskirts of the small town of Hotha, vary from 23 to 25, but in Himalayan
examples of the species there are occasionally 26 rows of scales. The ventrals in
the two specimens in which the second labial does not enter into the facial pit
number 151 and 156 each, with 41 and 57 sub-caudals respectively with the anal
1 Journ. As. Soc., 1871, p. 443.
in both entire. To illustrate the variations which occur in the ventrals and
sub-caudals of this species I give the following table.
Sikkim . . . . .
Bengal ? (British Museum specimen)
Nepal
Sikkim .
Yunnan
Do.
Himalayas
Datjeeling.
Yunnan
135
137
148
150
In one of these Yunnan specimens with the divided second labial, many of the
sub-caudals are simple.
There is thus in this species a variation in the ventral and sub-caudal shields of
21 to 32 respectively, and the preceding table would seem to indicate that when
there is a diminution in the number of the ventrals, there is not of necessity any
corresponding reduction of the sub-caudals, and vice versa. I have recorded elsewhere,
1 that variations in the number of head-shields are inaugurated in utero,
and I have observed that the number of the ventrals and sub-caudals vary in the
individuals of a brood.
The shields or scales between the supranasals, as is in other species of Trimeresuri,
are variable and do not offer any specific characters. They may either be
absent or be represented by one or by a pair of small scales or shields.
An adult female measures 30 inches, of which the tail is 4’50 inehes, and a
male 6T2 inches and its tail 3-35 inches.
A closely allied, if separable form, is the young snake from Penang described by
Stoliczka as T. convictus2 and which he long hesitated to separate from this species.
VIPERIDiE.
Genus D a b o i a , Gray.
D a b o ia r u s s e l l i i , Shaw.
Coluber russellii, Shaw, Gen. Zool., 1802, vol. iii, p. 418.
Vipera daboia, Daud., Rept., 1802, vol. vi, p. 119; Wagl., Syst., 1880, p. 177.
Vipera elegans, Daud., Rept., vol. vi, p. 124, pi. Ixxiii; Wagl., Syst., 1830, p. 177; Schleg.,
Phys. Serp., 1887, vol. ii, p. 588, pi. xxi, figs. 4 and 5.
Coluber (riserialns, Hermann, Ohs. Zool., 1804, vol. i, p. 278.
Echidna elegans, Merr. Tentam., 1820, p. 158; Dum. & Bibr., 1854, vol. vii, p. 1485.
Daboia pulchella, Gray, Zool. Misc., 1842, p. 69.
Daboia russellii, Gray, Zool. Misc., 1842, p. 69; Cat. Snakes, 1849, p. 24; Giittth., Rept. B. Ind.,
1864, p. 896; Theobald, Descr. Cat. Rept., Brit. Ind., 1876, p. 217; Stol., Journ. As. Soc.,
1 Proc. Zool. Soc., 1871, p. 180, p. 195.
* Joum. As. Soc., Bengal, 1870, vol. xxxis, p. 224.