AMPHIBIA AND REPTILIA OF COLORADO 85 



on their mesial edges. Top of the head dark brown to almost black, 

 lighter in the rostral region; labials and postorbitals yellowish or 

 bluish, the labials rather completely crossed at their junctions by 

 black bars. Each ventral with a dark spot on its anterior margin at 

 or just below its junction with the first row of scales, the remainder of 

 each ventral usually of a uniform color, although not infrequently with 

 small black dots or clouds of color. 



This description will cover only average specimens. The variation 

 in color is considerable, so that the various elements of the pattern 

 may be either accentuated or obscured. 



The food of this active species has been reported by numerous 

 observers. The smaller individuals feed upon earthworms, insect 

 larvae and small tadpoles. As the snake grows, larger food is taken, 

 frogs, large tadpoles, fish, in addition to insects of various sorts. 

 They are particularly fond of grasshoppers. Ruthven^ has observed 

 this species feeding upon the tree frog, Chorophilus nigrUus. In habit 

 Thamnophis radix is almost amphibious, being foimd most abundantly 

 in the sloughs and high grass near streams. When disturbed it will 

 go into the water, where it swims and dives actively. It is rarely 

 taken more than a mile from water and the swampy zone along streams 

 is to be regarded as its habitat. It is a viviparous species and pro- 

 duces from fifteen to forty young at one time. These are bom in the 

 latter part of the summer, although a specimen taken at Boulder, 

 Colo., in early July, 1912, contained twenty well-developed embryos. 



Thamnophis radix is strictly a species of the plains region. It 

 ranges from western Indiana to the foothills of the Rocky Mountains, 

 north into Canada and south to Oklahoma. 



Colorado specimens.— University Museum: Boulder, April 29, 1906 (4 

 specimens, 430-710 mm.). No. 227; University Campus, Boulder, October, 1906 

 (2 specimens, 500 and 580 mm.), No. 228; Niwot, August 31, 1911 (725 mm.), 

 F. Rohwer, No. 226; near Boulder, July 7, 191 2 (190 mm.), M. M. Ellis, No. 230; 

 Julesburg, July 17, 1912 (660 mm.), J. Henderson, No. 229; Boulder, October 29, 

 1912 (240 mm.), M. M. Ellis, No. 231; Colorado State Historical and Natural 

 History Museum: Denver, June 27, 1890 (540 mm.), H. G. Smith; Denver, July 

 31, 1890 (460 mm.), H. G. Smith; Denver, August 15, 1900 (960 mm.), W. C. 



■ U.S.XM. Bull. 61, p. 75, 1908. 



