Key 



b. Head shorter (three to three and a half times in total length); 

 spots outlined with light. North America, east of the Rocky 

 Mountains. 



Rana pipiens. (See Colour Plate XI, also p. 171.) 



B. Skin corrugated with elongated warts between the lateral folds and on 



the sides; definitely^outlined rounded spots on back and sides; length 

 of leg to heel not as great as total length. 



1. Head long (two and a half times in total length). Florida. 



Rana asopus. (See Colour Plate XIV, also p. 193.) 



2. Head shorter (one-third total length). Southern United States. 



Rana areolata. (See Fig. 223, also p. 192.) 



C. Skin relatively smooth between the lateral folds. 



1. Ear of male larger than eye; legs short; no black cheek-pa^ch. 



a. With definitely outlined spots on back and sides; size small (2J 

 inches); web large. Nevada, Utah. 



Rana onca. (See Colour Plate II, also p. 196.) 



6. Without pattern of spots; size 3^ or 4 inches. Throat of male yel- 

 low. Eastern North America. 



Rana clamitans. (See Colour Plate XIII, also p. 198.) 



2. Ear of male not larger than eye; legs long; black cheek-patch usually 



present. 

 a. With red in the colouration. 



(i) Leg to heel equal to total length; skin unusually smooth. 

 Northern Pacific region. 



Rana aurora. (See Colour Plate XIV, also p. 216.) 



(2) Leg to heel not equal to total length; skin may be tubercular 

 in old specimens; size large. Pacific region. 



Rana drayionii. (See Colour Plate XV, also p. 213.) 



h. No red in the colouration; brown or grey. 



(i) Length of leg to heel exceeds total length. Eastern North 

 America. 



Rana sylvatica. (See Colour Plate XIV, also p. 205.) 



(2) Length of leg to heel just equals total length, or is less than 

 total length. Northern United States and Canada. 



Rana caniabrigensis. (See p. 211.) 



D. Skin very tubercular over the whole upper parts; webs conspicuously 



large and broad. 

 I. Leg short (length to heel equal to length of body forward to ear); sole 

 of foot rough with tubercles; eye set obliquely. Northern Pacific 

 region. 



Rana pretiosa. (See Colour Plate XVI, also p. 218.) 



49 



