214 VERTEBRATE ANIMALS OF THE UNITED STATES 



F. abacura (Holbrook). Horn snake; mud snake. Length 1,250 

 mm.; tail 160 mm.; color blue-black, with a series of large red spots on 

 each side; abdomen red, blotched with black; a horny spine at the end 

 of the tail: Atlantic and Gulf States from Virginia to Louisiana, and 

 up the Mississippi Valley into Indiana; in wet woods, burrowing under 

 logs and in the sand; common in the south. 



4. Diadophis Baird & Girard. Ring-neck snakes. Small snakes 

 with a flattened head and a yellow ring around the neck: 4 species; 

 terrestrial, burrowing, feeding on earthworms, etc. 



Key to the Species of Diadophis 



ai Scales in 1 5 rows. 



bi In the eastern States D. pimctatus. 



b2 On the Pacific slope D. amabilis. 



a,2 Scales in 17 rows. 



bi In the central States D. arnyi. 



bo Along the Mexican border D. regalis. 



D. punctatus (L.) Length 330 mm.; tail 70 mm.; color dark gray or 

 black, with a yellow collar; belly orange, sometimes with black spots; 

 ventrals about 155: United States east of the Mississippi; common. 



D. arnyi Kennicott. Length 310 mm.; tail 50 mm.; color dull 

 black, with a narrow yellow collar; belly yellowish, spotted with black; 

 body slender: Ohio to Iowa, and southward into Texas; common. 



D. amabilis B. & 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. & 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 

 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. 

 a.1 Accessory scales around the azygous plate. 



bi Scales in 25 rows H. simus. 



hi Scales in 22, rows H. nasicus. 



