28 Records of the Indian Museum. [Vol. XV, 



In using this key care must be taken that the anus is correctly iden- 

 tified and that its natural position is ascertained. In some species of 

 Ranid larvae its dextral direction is not very strongly marked, while 

 in the Bufonidae it is usually situated at the end of a more or less tubular 

 sheath which is apt to be twisted "post mortem to one side or the other. 

 The only Ranid larva likely to be found in the plains of India in which 

 the horny teeth are absent is that of Oxyglossus lima, a species said to 

 occur in Bengal. In the tadpole of this genus the mouth-disk is very 

 feebly developed and the closed mouth appears as a vertical slit. 



The Engystomatidae will be dealt with in another paper (pp. 41- 

 45, fostea). 



Family RANIDAE. 



It does not seem possible (except in the case of Oxyglossus, the tad- 

 poles of which differ from those of all other Ranidae^ in the vestigial 

 character of the upper lip and in the absence of horny teeth on the 

 mouth-disk) to distinguish the larvae of the different genera of this 

 family. 



Key to the Ranid Larvae found in the Plains of India. 



I. Mouth-disk poorly developed ; lower lip horseshoe- 



shaped ; no horny teeth ..... Oxyglossus lima, 



II. Mouth-disk well-developed ; at least three transverse 



rows of teeth (as a rule at least one of them in'er- 

 rupted in the middle-line) present on the disk. 



A. Three rows of teeth on the mouth-disk. 



1. Beaks shallow ; long finger-shaped processes on the 



lower lip .......? Rana hrevipalmat'j . 



2. Beaks stout ; processes on lower lip short. 



(a) Habit stout; tail spotted with blick, not more 



than twice as long as head and body . . R. cyanophlyctis. 



(6) Habit rather slender; tail wi h )ut black spot?, 



more than twice as long as head and body . R. hexadactyla. 



B. More than three transverse rows of teeth on disk. 



1. Five transverse rows of teeth on disk. 



(a) Habit very stout; snout broadly rounded; fringe 

 on margin of lower lip widely interrupted in 

 the middle line . . . . . , R. breviceps. 



(h) Habit slender ; snout bluntly pointed ; fringe 

 on margin of lower lip not or slightly inter- 

 rupted, 

 (i) Dorsal profile of tail strongly sinuate ; fringe on 

 margin of lower lip papilliform^ uninter- 

 rupted ....... R. limnocharis. 



(ii) Dorsal profile of tail not sinuate ; fringe on 

 margin of lower lip digitiform, slightly 

 interrupted in the middle . . . . R. tytleri. 



2. Seven rows of teeth on mouth-disk . . . Rhacophorus 



macxdatus. 



3. More than seven rows of teeth on mouth-disk. 



(a) Interior of mouth inside beaks armed with a 



horny plate on the palate and a hornj' tubercle 



on each side ; not more than five tooth-rows 



on upper-lip ; lips rather feebly developed, 

 (i) Abdomen nearly flat ..... Rana tigrina. 

 (ii) Abdomen distinctly convex . . , . R. crassa. 



^ In those of two species of Rana from the hills of Southern India there are no horny 

 teeth, but the disk and beaks are well developed. See pp. 19. -20 of this volume. 



