52 UNIVERSITY OF COLORADO STUDIES 



burrows of their own construction. Because of this habit they are 

 rarely seen except in the spring when they come to water to lay their 

 eggs. At this time they are among the noisiest of amphibians. All 

 observers agree as to the remarkable power of the voice of these toads. 

 Professor A. E. Beardsley tells us that this toad is very abundant near 

 Greeley every spring. 



The Western Spade-foot Toad ranges through the Rocky Mountain 

 and Great Basin region. 



Colorado specimens. — Stale Teachers' College Museum: Greeley and near 

 Greeley, A. E. Beardsley. 



Family Bufonidae 



Genus BUFO Laurenti 



Bufo Laurenti, Synopsis Reptilium, p. 25, 1768. 



A large genus of cosmopolitan distribution. Tongue free pos- 

 teriorly and fastened to the floor of the mouth anteriorly; pupil of the 

 eye horizontal; digits, 4-5, toes webbed. The toads are of large 

 economic importance because of their feeding habits. It has been 

 shown by various observers that the number of insects destroyed by 

 a single toad is remarkable. Since toads are absolutely harmless and 

 are quite inoffensive, they should be protected. Five forms are 

 recorded from Colorado. 



a. Top of the head without bony crests. 



b. Ventral parts spotted; parotoids rounded ; webbing between the digits 

 deeply indented B. boreas Baird and Girard. 



bb. Ventral parts unspotted; parotoids elongate, wider posteriorly; webs 



short B. debilis Baird. 



aa. Top of the head with elevated bony crests. 



c. Median crests parallel, joining the lateral crests at right angles; no 

 diagonal crests B. woodhousei Girard. 



cc. Median crests diverging posteriorly. 



d. A short, diagonal crest, directed mesially from the angle at the 

 junction of the median and lateral crests on each side. 



B. americanus LeConte. 

 dd. No diagonal crest ; median crests diverging widely posteriorly. 



B. cognatus Say. 



