196 COLTTBEID*. 



Onlj' the outer row of scales smooth. ; ven- 



trals 130-146 ; suboaudals 64-92 .... 33. asperrimus, p. 232. 



Only the outer row of scales smooth ; usu- 

 ally a single labial entering the eye ; 

 ventrals 145-161 ; subcaudals 54-69 . . 34. annularis, p. 233. 



3. Scales in 19 to 23 rows, strongly keeled ; a single anterior 

 temporal ; one or two labials entering the eye. 



a. Head distinct from neck. 



a. Ventrals 160-197; scales in 19 rows; 4th, or 4th 

 and 5th labials entering the eye. 



35. tessellatiis, p. 233. 



p. Ventrals 147-160; scales in 21 or 23 rows; 3rd 

 and 4th labials entering the eye. 



36. viperinus, p. 235. 



y. Ventrals 126-147 ; scales in 19 or 21 rows ; 4th and 

 5th labials entey:ing the eye. 



Frontal twice as long as broad; scales 



usually in 19 rows, outer row faintly 



keeled 37. validus, p. 237. 



Frontal once and two thirds to twice as 



long as broad ; scales in 21 rows, outer 



row distinctly keeled 38. clarhii, p. 238. 



Frontal broad ; tail compressed at the [p. 238. 



base 39. compressicauda, 



b. Head small, not or but scarcely distinct from neck ; scales 



in 19 or 21 rows ; third and fourth labials entering the 

 eye. 



Frontal hardly once and a half as long as 



broad ; ventrals 140-151 ; subcaudals [p. 239. 



64-86 40. septemvittatus. 



Frontal twice as long as broad; ventrals 



132-142; subcaudals 51-71 41. rigidus, p. 240. 



Frontal once and two thirds to twice as 

 long as broad ; ventrals 156-173 ; sub- 

 caudals 47-65 42. grahami, p. 240. 



4. Scales in 21 to 27 rows ; not more than one labial entering 

 the eye. 



Eye separated from the labials by subocu- 



lars ; frontal once and one third to once 



and a half as long as broad 43. ferox, p. 241. 



Eye separated from the labials by subocu- 



lars ; frontal elongate 44. anoscopus, p. 242. 



Fourth labial entering the eye 45. fasciatus, p. 242. 



