416 BOULENGER. 



moderately broad, usually with interrupted folds or elongate warts 

 between them; outer metatarsal tubercle absent or very indistinct; 



vocal sacs external or internal R. halecina, L. 



Head as long as broad; interorbital space much narrower than upper 

 eyelid; dorso-lateral folds very broad, with a pair of similar folds 

 between them; outer metatarsal tubercle usually present; vocal sacs 



internal R. palustris, Leconte. 



b. Male without vocal sacs. 

 Head broader than long; interorbital space as broad as or narrower 

 than upper eyelid ; tympanum f to once diameter of eye; outer meta- 

 tarsal tubercle absent or very indistinct R. draytonii, B. & G. 



Head as long as broad or slightly broader than long; interorbital space 



narrower than upper eyelid; tympanum f to | diameter of eye; 



more or less distinct outer metatarsal tubercle. . . .R. aurora, B. & G. 



2. Web not penetrating beyond basal third or half of outer 



metatarsals. 



a. Glandular dorso-lateral fold narrow or moderately broad; 

 head moderately' large; vomerine teeth on a level with 

 or behind posterior borders of choanse. 



Tibio-tarsal articulation reaching tympanum or eye; tibia 3 to 4^ 

 times as long as broad, 2 to 2^- times in length from snout to vent; 

 toes f to nearly entirely webbed; inner metatarsal tubercle i to f 



length of inner toe; male without vocal sacs R. pretiosa, B. & G. 



Tibio-tarsal articulation reaching tympanum or eye; tibia 3 to 4 

 times as long as broad, 2 to 2\ times in length from snout to vent; 

 toes J to f webbed; inner metatarsal tubercle | to f length of inner 



toe; male with internal vocal sacs R. cayitabrigensis, Baird. 



Tibio-tarsal articulation reaching beyond eye; tibia 4 to 5 times as 

 long as broad, if to 2 times in length from snout to vent; toes f to f 

 webbed; inner metatarsal tubercle f to f length of inner toe; male 

 with internal vocal sacs R. silvatica, Leconte. 



b. Glandular dorso-lateral fold broad; vomerine teeth be- 

 tween the choanae. 



Head moderate; loreal region fully oblique; tibio-tarsal articulation 

 reaching eye; tibia 4| to 5 times as long as broad, 2t to 2-g- times in 

 length from snout to vent; toes f webbed; male without vocal sacs. 



R. godmani, Stur. 

 Head very large; loreal region very oblique; tibio-tarsal articulation 

 reaching tympanum or eye, or a little beyond; tibia 3 to 4 times as 

 long as broad, If to nearly 2| times in length from snout to vent; 

 toes ^ webbed; male with external vocal sacs. .../?. areolata, B. & S. 



