204 



VERTEBRATE ANIMALS OF THE UNITED STATES 



D. amahilis B. and G. Length 430 mm. ; tail 90 mm. ; color bluish or 

 greenish-black with a reddish collar; belly reddish: Oregon to Lower 

 California; common. 



D. regalis B . and G. Length 600 mm. ; color dark bluish-gray above ; 

 belly yellow or reddish, with many small black spots; coloration some- 

 times faint or absent : Texas to Arizona. 



5. Heterodon Latreille. Hog-nosed snakes (Fig. 117). Moderate 

 sized snakes with a broad, upturned snout (rostral plate) and an extra 

 plate (the azygous) back of the rostral; scales in 23 to 25 rows; ventrals 



Fig. 117. — Heterodon conlorlrix {from Cope). 



about 140; upper labials 8: 4 species, all in the eastern and central 

 States; terrestrial, feeding on toads and insects and burrowing with the 

 peculiar snout ; when alarmed they dilate and flatten the neck and head 

 while hissing loudly, and often throwing themselves into contortions 

 or feigning death; they are harmless. 



Key to the Species of Heterodon 



ai No accessory scales around the azygous plate; scales in 25 rows. .H. contortrix. 

 ao Accessory scales around the axygous plate. 



bi Scales in 25 rows //. simus. 



hi Scales in 23 row^s H. nasicus. 



H. contortrix (L.) {H. platyr/iinus La.trei\\e) (Fig. 117). Puffing or 

 spreading adder; blowing viper. Length 700 mm.; color brown or 

 reddish, with about 28 dark or black dorsal patches between the head 

 and tail, and a series of similar patches on each side alternating irregu- 



