2 40 ANURA CHAP. 



remainder of South America being \Yithout any Eaninae. All 

 the species of the whole Periarctic region belong to the genus 

 Rana except in Eastern Asia, where the closely allied genus 

 Ehacoplwrus occurs also. The entire sub-family of Raninae is, in its 

 fulness and diversity of development, essentially Palaeotropical. 



Many of the genera, even in the present more liberal sense as 

 interpreted by Boulenger, are based upon unimportant characters, 

 and in reality run into each other. This is for instance the case 

 with Rana and Rliacoiihorus. 



The following tabular arrangement is merely a key for 

 determination and does not necessarily express relationships. 

 The presence or absence of vomerine teeth is a character easily 

 ascertained, but it separates closely allied genera, for instance, 

 Rhacophorus from Ixalus and Micrixalus from Rana. 



The genera with extra, interpolated phalanges are marked *. 



Key for the determinatiox of the genera of Kaninae. 



1. Pu])il vertical. 



-I. With vomerine teeth. 



((. Oiiiostenium very sleiiderand cartilagin- 

 ous. Small discs. India and Ceylon, 

 3 species ..... Nannohatrachus. 

 h. Omosternum with a bony style. 



a. Outer metatarsals ■\\'elibed. Small 



discs. South India, 2 species . Nyctibatrachus. 

 (i. Outer metatarsals close together. Africa. 

 Fingers and toes with inter- 

 polated i^halanges. 



Without terminal discs. 



2 species . ... Cassina.'^ 



With discs supported by 

 claw-shaped phalanges, 

 10 s]iecies . . . Hylamhates* 



Fingers and toes without inter- 

 polated phalanges ; with- 

 out discs. 



Toes web1)ed . . Trichobatrachus rohHstus, 



p. 271. 

 Toes free, with sliaip 



claws . . . Gampsosteonyx batesi, 



p. 272. 

 i). Without vomerine teeth. Discs well de- 

 veloped. Outer metatai-sals united. 

 Tropical Africa and Madagascar, 7 si)ecies Megalixalus* 



