40 UNIVERSITY OF COLORADO STUDIES 



Professor T. D. A. Cockerell, and Messrs. W. L. Burnett, L. J. 

 Hersey, J. C. Smiley, H. G. Smith and A. G. Vestal. 



Systematic Account 



By means of the following key any of the forms found in Colorado 

 belonging to the classes Amphibia and Reptilia may be separated 

 readily, although considering these classes as a whole, there are forms 

 which it does not cover. The detailed zoological definitions of these 

 classes are given under the class headings, which descriptions cover 

 all forms. 



A. Body smooth, without scales or other epidermal structures on the body; 

 frogs, toads, salamanders and tree frogs. Class AMPHIBIA (page 48). 

 AA. Body with scales or epidermal plates of some sort (excepting the soft- 

 shelled turtles, which may be recognized by their dorsal and ventral 

 shields); snakes, lizards and turtles. Class REPTILIA (page 61). 



Class AMPHIBIA 



Poikilothermous vertebrates with two occipital condyles, most 

 species with functional gills in the early stages; skin without scales 

 (except in the Gymnophiona) ; embryo without amnion and allantois, 

 usually passing through a "tadpole" stage. 



A. Tail present throughout life. 



Order CAUDATA, the Salamanders and Newts (page 48). 

 AA. Tail not present in the adult stage. 



Order SALIENTIA, the Toads and Frogs (page 50). 



Order CAUDATA 



This group of Amphibians, although fairly large, is represented by 

 but a single species in Colorado. 



Family Ambystomidae 



Four limbs present and well developed; eyes with eyelids; side 

 of the head without a spiracle in the adult. This family of Salaman- 

 ders is represented in North America, South America, Asia and Japan, 

 although the majority of the species are found in the new world. 



