42 SYNOPSES AND DESCRIPTIONS. 
large, posterior two small. Submentals two pairs. Seales smooth, in 
17 rows, medial narrow, outer and caudal as broad as long. Ventrals 
175—190. Anal entire. Subcaudals 80—110 pairs. 
Uniform lustrous black above, varying to olive or leaden, more or less 
yellow, on the western prairies; chin, throat, and portions of the labials 
white. The white extends upward behind the jaws, or is limited to the 
chin. 
The young are olivaceous with a dorsal series of large, darker-edged, 
irregular-shaped brown spots, the largest of which forms a transverse 
band immediately behind the head. Sides and abdomen with irreg- 
ularly placed spots of brown, varying in size from that of a dot to 
that of a couple of scales. The spots become obsolete backward. Head 
yellowish brown above, spotted or mottled with dark, below yellowish. 
Mississippi Valley and eastward. 
var. FLAVIVENTRIS. 
Say, 1823, Long’s Exp. II, 185. 
The “Blue Racer” of the prairies is rather stouter than the “Black 
Snake” of the Eastern States. On the back it is light olive, greenish 
or blueish; beneath yellowish, some of the scales and interspaces showing 
darker. The young are mottled like those of the black snake and without 
spots below. 
var. MENTOVARIUS. 
CoryPHODON MENTOVARIUS Duméril & Bibron, 1854, Erp. Gén. VIT, 187. 
Back greenish-brown. <A single labial entering the orbit. This species 
resembles greatly C. constrictor; it is distinguished by the single labial 
beneath the eye. The head is comparatively more elongate, and the eye 
larger. The hinder submentals are longer than the anterior, which is not 
the case in C. constrictor. (Dumeéril.) Mexico. 
CoLUBER FLAGELLIFORMIS. 
Holbrook, 1836, N. A. Herp., ed. I, 107, pl. XIX. 
Long, slender, with flat belly; head distinct, elongate, narrow, subquad- 
rangular in transverse section, as deep as wide at the eyes, crown flat, bent 
downward slightly in front of the orbits; tail long, near one fourth of total, 
slender, tapering regularly to the tip. Eyes large, over the fourth and 
