SYNOPSES AND DESCRIPTIONS. 41 



Scales in 17 rows ; 

 anal entire; 



back plumbeous to black, in adults ; 



two labials in the orbit constricior. 



one labial in the orbit mentovarius. - 



{Masticoj^ihis.) 



Anal bifid; 



dinoy white, mixed with brown, varying to black on the anterior 



^lalf of the body flcujdUformis. ^ 



reddish-brown; anterior scales darker in the center, posterior 



with a light spot at the base testaceus. 



color in longitudinal bands ; 



three preoculars ; brown darkening anteriorly 



auriffitlKs. 



one preocnlar; 



bands broken into transverse blotches anteriorly 



mexicanus. 



a yellow band on vertebral rows; a black line at ends of 

 ventrals spinalis. 



Scales in 15 rows ; 



a broad band of dark color on the back; flanks with narrow lines of 

 light color, separated by dark. taeniatus. 



Coluber constrictor, fl IV, fr/. 3. 



Linm; 1758, Sysl. Nat., cd. X, I, 210; 17(1(;, ed. XII, I, ?..Sr,. 



Elongate, slender, slightly compressed; head distinct from the neck, 

 long, narrow, angled in front, concave on the sides, crown flat, curving 

 downward near the snout; tail about one fourth of the total, slender. 

 Eyes large, over the third and fourth labials, pupil round. ISTouth-cleft 

 deep, curved. Crown-shields normal. Prefrontals bent downwar.l ..n tlie 

 side of the head. Rostral broad, very convex. Nasal in two parts, nostril 

 between. A loreal. Preoculars two, sometimes but one, lower very small, 

 in a notch between the second and third labials. Postoculars two (2—3), 

 lower resting on the fourth labial. Temporals 2+2^-2. Labials seven 

 (7_8), fourth, sixth, and seventh larger. Infralabials nine, fifth very 



