1920.] G. A. Boui^ENGER : Frogs of the Genus Rana. 



3. No tympanum ; outer metatarsals separated in the distal third or fourth ; 



omosternum entire. 

 N anor ana, Gihr. Monotype: A^. /j/e^^e/, Gthr., Kashmir and Thibet. Con- 

 nected with the R. liebigii group through R. blanfordii, Blgr. 



B. Toes, often also fingers, dilated at the end, the dilatation, or disc, bearing a 

 crescentic or horseshoe-shaped horizontal groove. 



1. Outer metatarsals united or separated only in the distal third ; omosternum 



forked at the base. 

 Discodeles, Blgr. Type: A^. guppyi, Blgr. 6 Indo-Malayan species, 3 Mela - 

 nesian. Connected with Rana {R. grunniens group) ; leads to the Indo-Malayan, 

 Papuan, and Melanesian genera Covniifey, Tsch., and Platymantis, Gthr. 



2. Outer metatarsals separated at least in the distal half ; omosternum entire. 

 Hylovana, Tsch. Type : R. erythraea, Schleg. 58 South Asian species, i 



African, 5 Papuan and Melanesian. Completely connected with Rana [Ranae 

 typicae) ; leads to the Indo-Malayan genera .S/az/ro/^, Cope, and Simomantis, Blgr.i 



II. Clavicles very slender, curved or directed obliquely backwards, widely sepa- 

 rated on the median line. 



A. Outer metatarsals united ; omosternum entire. 



Hildebrandtia, Nieden. Type: R. ovnata, Peters. 7 species from Africa. 

 Burrowing forms. 



B. Outer metatarsals separated ; omosternum forked at the base ; distal pha- 



langes claw-shaped. 

 Ptychadena, Blgr. Type : R. niascareniensis, D. et B. 16 species from Africa. 



These two last subgenera are probably derived^ as divergent 

 series, from a common ancestral type connected with the subgenus 

 Rana. 



The following diagram expresses the relations between these 

 subgenera, as I conceive them. 



Ptychadena. Aubria. Hylorana. Discodeles. Nanorana. 



Hildebrandtia 



Tomopterna. ■ 



-Rana.- 



-Pyxicephalus. 



Subgenus Rana, s. str. 

 Synopsis of the Speciks. 



I. Dorso-lateral glandular fold absent or, if present, not connected with the 

 supratemporal fold ; outer metatarsals separated at least in the distal half. 

 A. Tympanum very distinct, smooth ; nasal bones in contact with each other, 

 with two exceptions ^ ; omosternal style forked at the base. 

 I. Inner metatarsal tubercle small but very prominent, pointed, digitiform ; 

 fingers pointed ; toes webbed to the tips ; male with external vocal sacs. 

 Vomerine teeth in strong oblique series in the adult ; 

 first finger longer than second ; toes pointed ; tibia 

 2 to 2i times as long as broad ; throat and belly with 

 granules and small warts ... ... .. R. hexadacty/a, l.ess. 



1 Cf. Boulenger, Ann. and Mag. N. //. (9) I, 1918, p. 372. 



2 /?, microdisca and palavanensis. 



