cc. Without transverse fold of skin across head, be- 

 hind eyes; size medium to large, i 1/2-8 4/5 

 inches (37-220 mm.), except B. debilis and B. 

 quercicus (2/3 inch); tympanum distinct or in- 

 distinct; parotoids present except in 2 species of 

 Scaphiopus; feet with extensive fleshy webs; 

 snout blunt; eyes large; head broad. 

 d. Pupil vertical (by day); parotoids absent in 

 2 species, present but rounded and indistinct 

 in 1 species; sole without subarticular tuber- 

 cles; skin relatively smooth; venter smooth; 

 no cranial crests; males without discolored 

 throats. 



Spadefoots. Scaphiopodidae. Plates VI-VIII. 



dd. Pupil not vertical; parotoids present and ele- 

 vated; sole with subarticular tubercles; skin 

 warty; venter usually granulated; cranial 

 crests present in most species, lacking in 

 Bufo boreas, B. canorus, B. compactilis^ B. 

 debilis y B. punctatus; males usually with dis- 

 colored throats. 



Toads. Bufonidae. Plates IX-XXIV. 



bb. Waist narrow; body narrower and thinner; hind 

 limbs long; no parotoid. 

 c. Disks on digits; neither thumb nor other fingers 

 enlarged in male. 

 d. Disks transverse; venter usually smooth; 

 subarticular tubercles saw-toothed; eggs large; 

 male throat not discolored. 



Robber frogs. Leptodactylidae. Plates L-LV. 



dd. Disks round, large or small; pupil elliptically 

 horizontal; subarticular tubercles rounded; 

 venter usually granular or areolate; male 

 throat discolored. 



Tree frogs. Hylidae. Plates XXV-XLIX. 



cc. No disks on digits; extensive webbing on toes; 

 thumb of male enlarged at base; venter smooth. 



True frogs. Ranidae. Plates LVI-LXXVIII. 



H 



