HETERODON. 51 



Genus flETElKODOIV, Pal. de Beauv. 



Gen. Char. Body short, stout, tail short. Head, neck, and 

 body capable of excessive dilatation. Posterior palatine teeth longer. 

 Head broad, short; outline of mouth very convex, on a single curve. 

 Orbit enclosed by a continuous chain of small plates, the circle com- 

 pleted above by the superciliaries. Rostral prominent, its anterior 

 face very broad, and turned up ; its ridge above sharp. Behind it a >": .- H^ 

 median plate, either in contact with the frontals or separated by small 

 plates. Frontals in two pairs. Nasals two/ Loral one or two/ Dor- /h^Jj^ 

 sal rows of scales 23-27, carinated. Abdominal scutellae 125-150, J ^ l> ttf ^ 

 posterior bifid. Subcaudal scutellse all bifid. 



Colors light, with dorsal and lateral darker blotches, or else brown, 

 with dorsal transverse light bars. Sometimes entirely black. 



The species exhibit a very threatening appearance when alive, in 

 flattening the head, hissing violently, &c. but are perfectly harmless. 



Syn. Heterodon, Pal. de Beauv. in Latr. Hist. Nat. des Kept. 

 IV, 1799. , 



A. Azygos behind the rostral, in direct contact with the frontals. 



1. Ileterodon platyrllillOS, Latr. — Occipitals and vertical longer 

 than broad, about equal in length. Centre of eye anterior. Dorsal rows 25, 

 all carinated, the outer sometimes smooth. Keels of the scales extending 

 to their tips. Scales on the back quite linear anteriorly, posteriorly they 

 are much broader. Color yellowish gray, or brown, with about 28 dark dor- 

 sal blotches from head to anus, and 15 half-rings on the tail. One or two 

 lateral rows. Beneath yellowish. A dark baud across the forehead in front 

 of the vertical, continued through the eye to the angle of the mouth. 



Syn. Coluber heterodon, Davd. Hist. Nat. Kept. VII, 1799, 153. PI. Ix. 

 fig. 28.— Say, Amer. Journ. of Sc. I, 1818, 261.— Harl. Journ. Acad. Nat. 

 Sc. Philad. V, 1827, 357; and Med. & Phys. Res. 1885, 120. 



Heterodon platyrhinos, Latr. Hist. Nat. Rept. IV, 1799, 32, fig. 1-3. 



— HoLBR. N. Amer. Herp. II, 1828, 97. PI. xxi ; and 2d ed. IV, 1842, 67. 

 PI. xvii. 



Hog-nose Snake ; Blowing Viper. 



