122 
ZOOLOGY OF THE FAR EAST. 
cancrivora^ Gravenhorst. The difficulty about them lies largely in the fact that poorly 
preserved examples are much less easy to distinguish than living or recently killed 
specimens. No one could confuse living frogs of the form I call R. cancrivora with 
the true Rana tigrina of India, but if specimens have become sodden and discoloured 
it is very difficult to distinguish between them. Indeed, the only really satisfactorily 
preserved specimens that I have seen are those that have been hardened in fairly 
strong formalin and then transferred to alcohol, each specimen having been killed 
and kept until hard in a separate bottle or tin of comparatively large size. However, 
the notes that Dr. Boulenger and Dr van Kampen have been kind enough to send 
me prove that with a practised eye it is possible to distinguish even specimens pre- 
served with much less care. 
Daudin's original figure of R. tigrina was evidently drawn from a frog that had 
been distorted by pressure and had become discoloured, but it shows the character- 
istic shape of the snout and the fully webbed, coarse toes of the species. The figure 
reproduced in Boulenger 's volumes in the Fauna of India and the Fauna of the Malay 
Peninsula is an admirable likeness of this frog. 
No satisfactory figure of Rana cancrivora has hitherto been published, but 
Wiegmann's original figure of R. rugulosa is good. 
The three species may be distinguished as follows: — 
I. Feet almost fully webbed, the web extending at least as far as the base 
of the terminal phalanx of each toe, and being very little emarginate. 
A. Snout distinctly pointed ; ventral surface immaculate or practically 
so . . . . . . . . . . . . R. tigrina. 
B. Snout rounded; ventral surface, or at any rate the throat, spotted 
or reticulated with black . . . . . . . . R. rugitlosa. 
II. Web of feet distinctly emarginate between the toes, not reaching the base 
of the terminal phalanx of the fifth toe. 
Snout rounded ; ventral surface, or at any rate the throat, blotched or 
marbled with brown ; a white spot often present at the proximal 
end of the external metatarsal fold . . . . . . R. cancrivora. 
These characters are best seen in fully adult frogs that have not yet attained 
old age. The colouration of the young Rana tigrina is quite distinctive. 
Rana tigrina, Daudin. 
(Plate V, figs. 1-2, pi. VI, figs, i, la). 
1803. Rana tigrina, Daudin, Hist. Ran., p. 64, pi. xx. 
1882. Rana tigrina, Boulenger, Cat. Batr. Sal. B.M., pp. 22-27 (i" part). 
1890. Rana tigrina, id.. Faun. Brit. Ind., Rept., pp. 449, 450 (in part), fig. 132. 
1915. Rana tigrina, Nicholls, Proc. Zool. Soc. London, II, pp. 603-609. 
Larva. 
1904. Rana tigrina, Ferguson, Journ. Bom. Nat. Hist. Soc, XV, p. 501. 
In fresh specimens of R. tigrina (s.s.) the habit is rather slender than stout but 
moderate rather than extreme in either direction. The head (measured from the 
