4 Records of the Indian Museum. [Vol. XX, 



middle line of the thigh where it joins the body. By foot is meant 

 the foot without the tarsus ; it is measured from the tarso-meta- 

 tarsal articulation. Each finger or toe is measured from the 

 point at which it joins its fellow, and if this is not the same on 

 both sides, as in the case of the fourth toe, from the point most 

 remote from the tip. The length of the first toe is reckoned from 

 the distal extremity of the base of the inner metatarsal tubercle. 



Genus Rana, I/. 



Tongue extensively free and more or less deeply notched and 

 bifid behind. Vomerine teeth (exceptionally absent). Pupil 

 roundish-subtriangular or horizontal, or rhombic and very contrac- 

 tile.' Fingers free, toes more or less extensively webbed (excep- 

 tionally nearly free). Omosternum and sternum with a bony st3de. 

 No intercalary bone between the penultimate and distal phalanges. 



Divided into 9 subgenera : — 



I. Clavicles strong, straight or feebly curved, horizontal or directed forward, 

 narrowly separated on the median line. 

 A. Digits not dilated at the end, or with dilatations devoid of horizontal groove. 



1. Tympanum present ; squamosal not forming a suture with the maxillary. 



a. Outer metatarsals separated by web, at least in the distal half. 



Rana, sensu stricto. Type : R. temporaria, L. 14 Eurasian species, 22 

 .-Xmerican, 11 African, 45 Indo-Malayan, i Papuan. 



b. Outer metatarsals united or separated only in their distal extremity; 



omosternum usually forked at the base.'^ 

 Tomopterna, D. et B. Type : T. delalandii, D. et B. 4 Indian species, 4 

 African. Burrowing forms, connected with Rana {R. tigrina-limnocharis groupl 

 through the Indian R. rufescens, Jerd. 



2. Tympanum present : squamosal forming a suture with the maxillary. 



a. Outer metatarsals completely united ; omosternuin entire. 

 Pyxicephalus, Tsch. Monotype : P. adspeysus, Tsch., Africa. Burrowing 



form like the preceding, probably derived from another group of Rana. 



b. Outer metatarsals separated in the distal third or fourth ; omosternum 



forked at the base. 



Aubria, Blgr. Monotype : /?. siibsigillata, A. Duni., Africa. Probably 

 derived from the R. tigrina group, like Tomopterna, but in a different direction. 



to ' tympanum ' as universally used. When we say the tympanum is distinct, we 

 do not convey the idea that it is exposed ; just as we are fully justified in stating 

 that the eye of a frog is distinct even when the transparent lower lid is drawn 

 over it. Mr. Baini Prashad has quoted various authors to show that "a great 

 deal of confusion exists regarding the tympanum being a structure distinct from 

 the skin or otherwise." He should ha\e referred to the introduction to my book, 

 •The Tailless Batrachians of Europe' (Ray Society, 1897), in which f'p. ii), 

 dealing with the external characters, I have thus described the state of things .— 

 "The tympanum, or drum of the ear, is absent \r\ Bombiiiatoy and Pelobates. 

 When present it may be concealed under the skin, as in some specimens of 

 Discoglossus, Pelodytes. and Bufo vulgaris, or appear on the temple behind the 

 eye as a round or oval disk covered with thin skin." 



1 As in R. corrugata, kuhlii and spinosa. 



2 The character suffers exceptions, as Miss Procter has pointed out to me 

 tliat the omosternum may be simple in specimens of R.delalandii. Is this to be 

 regarded as a case of reversion to the original condition ? It shows at any rate 

 that great systematic importance cannot be attached to the shape of the omo- 

 sternum. 



