SYNOPSES AND DESCRIPTIONS. 37 



Labials 8, sixth and seventh largest. Infralabials 10. Scales smooth, 

 lustrous, in 21 rows. Ventrals 160. Anal bifid. Subcaudals 65 pairs. 

 A band of black along each flank from the nostril to the tip of the tail. 

 One or two of the outer rows lighter. Dorsal region covered by a band 

 of greyish brown, lighter near the black bands. Labials, infralabials, and 

 chin-shields with rounded spots of black. Each ventral has a rounded 

 spot upon the base near each end which form a series along each side of 

 the abdomen. Southern Mexico and Central America. 



COLTTBRINAE. 



Elongate fusiform, stout to slender; head distinct from the neck, elon- 

 gate, crown flattened, sides concave; neck somewhat small; tail rather 

 long, not distinct from the trunk, tapering. Muzzle stout, produced. 

 Mouth deeply cleft, outline curved. Teeth subequal or posterior larger. 

 Eye large, pupil round. Scales smooth or keeled, imbricate; subcaudals 

 in two rows. 



The typical genera of the family are those of Coluber and Elaphis,. the 

 genera to which the common black snakes of the United States belong. 

 Nasal divided; 



edges of rostral free; scales smooth, in 17 series; 



posterior maxillary teeth longer, isolated, smooth 



Salvadoea. 

 Nasal entire; 



teeth equal, smooth; loreal present or lacking; 



anal bifid; scales smooth or keeled, in 15 or 17 series 



Cyclophis. 

 Nasal divided-; 



anal bifid; scales smooth or keeled; loreal present; 



teeth becoming longer posteriorly Coluber. 



anal entire; 



teeth equal smooth; a loreal; crown-shields nine; 

 scales keeled or smooth, in 15 to 23 series 



Spilotes. 

 scales keeled, in 27 to 35 series ; 



crown-shields nine to eleven Pityophis. 



