SYNOPSES AND DESCRIPTIONS, 51 
PITyorPHuis. 
Holbrook, 1842, N. A. Herp. IV, 7. 
Long, moderately stout, compressed; head distinct from the neck, sub- 
conical, broad posteriorly, pointed at the muzzle; tail rather short. Eye 
moderate, pupil round. Teeth equal, smooth. Crown-shields nine to 
eleven. Prefrontals one to two pairs. Nasal divided. A loreal, rarely 
suppressed. One to two preoculars. Postoculars two to five. Scales 
keeled, in 27 to 35 rows. The individual variation is very great in 
specimens belonging to species of this genus, particularly so in those of 
the Rocky Mountains, 
PITYOPHIS MELANOLEUCUS. 
Colter MELANoLEUCUS Daudin, 1799, Hist. Nat. Rept. VI, 409. 
Piryoruis MELANOLEUCUS Holbrook, 1842, N. A. Herp. IV, p. 7, pl. I. 
Long, moderately stout, slightly compressed; head moderate, distinct 
from the neck, appearing subquadrangular when viewed from the front, 
narrowing forward, conical or pointed, crown slightly convex, very broad 
behind; snout prominent; tail short, rather less than one seventh of the 
total, stout, tapering. Eye moderate, pupil round. Mouth-cleft deep, 
slightly curving. Crown-shields more or less irregular, commonly two 
pairs of prefrontals. Rostral very prominent, narrow, swollen, extending 
on the upper surface of the head, between the internasals. Internasals 
short, wide. Outer prefrontals extending on the side of the face to the 
loreal, inner narrow posteriorly. Frontal broad anteriorly. Supraciliaries 
prominent, broadening backward. Parietals large, nearly as wide as long. 
Nasal in two parts, nostril between. Loreal small, sometimes united with 
adjacent plates. One preocular. Postoculars three to four. Two or more 
temporals in contact with the postoculars, sometimes broken into small 
seales. Labials eight, fourth below the eye, fifth under the postorbital, 
seventh largest. Infralabials thirteen to fourteen, fifth and seventh large, 
hinder very small. A pair of large submentals, followed by a pair of 
smaller ones, which are separated by a pair of small plates. Scales 
lozenge-shaped, usually in 27 or 29 rows (ranging in the different varie- 
ties from 27 to 35), outer broad, lateral smooth, vertebral keeled. Ven- 
trals 212—216, broad. Anal entire. Subcaudals 58 to 60 pairs. 
Color whitish, tinged with red on the back, with a dorsal series of large 
spots of dark brown or black—becoming bands posteriorly—thirty or more 
