FAMILY COLUBERID®. 51 
GENUS HETERODON. Pal. de Beauvois. 
Teeth unequal ; the posterior maxillary teeth largest. Head triangular, pointed. Rostral 
plate pyramidal, triangular, ridged above, and pointed at the tip. 
THE HOG-NOSED SNAKE. 
HETERODON PLATYRHINOS. 
PLATE XIII. FIG. 28, a. PLares oF THE HEAD. —(CABINET OF THE LYCEUM.) 
Heterodon a large nez. LATREILLE, Hist. Rept. Vol. 4, p. 32. 
Heterodon. Daup. Vol. 7, p. 153. 
Coluber heterodon. Say, Am. Jour. Vol. 1, p. 261. Harzan, Med. and Phys. Res. p. 120. 
Heterodon platyrhinos. Hoiproox, N. Am. Herpetology, Vol. 2, p. 97, pl. 21. 
H. id. Storer, Mass. Rep. p. 23]. Troost, Ann. Lyc. Vol. 3, p. 183. 
Characteristics. Greyish tinged with yellowish, and a triple series of blackish blotches. 
i Dorsal series largest, bordered with black; lateral series smaller, and 
irregularly rounded. A dark band through the eyes. Length two feet. 
Description. Body robust, and covered with oval-oblong carinate scales ; the two or three 
series next to the abdominal plates, smooth. The body tapers rather suddenly from the vent. 
Tail short, one-sixth of the total length, ending in an acute tip. Ventral scale divided. Head 
large, triangular, flattened above, with a pointed snout. Teeth in the posterior part of the 
jaw long, hollow, not perforated, and four in number. The plates cover but a small portion 
of the head. Central plate irregularly six-sided, the lateral margins being longest, and the 
anterior meeting at an obtuse angle ; supra-orbital oblong, broadest behind, and projecting over 
the eye. Around the eye are arranged ten small orbital plates ; besides these, there are two 
pair of anterior nasal plates, of which the superior are largest, the lower plate being behind the 
posterior nasal plate, and furrowed in its centre. Nasal plates two on each side ; the anterior 
lunated behind, the posterior excavated in front to complete the nostril. Occipital plates 
triangular, with the apices truncated at their junction with the vertical plate. Frontal plate 
uniting laterally with the anterior and posterior nasal plates ; between the frontal plates is a 
long narrow azygous plate, ridged above, and uniting in a sub-imbricate manner on nearly the 
centre of this plate with the rostral plate. Rostral plate triangular, upturned in front, with a 
strong carina on its upper surface, and excavated beneath. Labial plates above eight on each 
side of the lower jaw ; nineteen in all. Nostrils large, lateral, and near the rostrum. Eyes 
large, prominent. Head in repose not much larger than the neck ; but when irritated, it 
distends to twice its usual breadth, the summit becoming flattened. 
Color. Brassy yellow above, with three series of irregular subquadrate or rounded deep 
chesnut, blackish or ash grey blotches, occasionally united on the posterior part of the body 
and tail, forming rings ; the series on the sides much smaller, and alternating with the larger 
ones. Summit of the head dark rufous, with irregular blotches and dots of dark brown. A 
