14 BULLETIN 18 7, UNITED STATES NATIONAL MUSEUM 



30. Vertebral scale row at least somewhat enlarged, or an azygous scale 



bordering mental posteriorly 31 



Vertebral scale row not at all enlarged; no azygous scale following 

 mental Tropidodipsas (part) (p. 149) 



31. Vertebral scales strongly enlarged; and no preocular Sibon (p. 126) 



Vertebral scales scarcely enlarged, or one or more preoculars (or both). 



Dipsas (part) (p. 49) 



32. Scales keeled over most of body Storeria (p. 156) 



Scales smooth, except perhaps on tail and near vent on body 33 



33. Scale rows 15 46 



Scale rows 17 34 



34. Internasals fused with anterior section of nasal Stenorrhina (p. 132) 



Internasals distinct from nasal 35 



35. Two or three preoculars (including suboculars, if any) 36 



One preocular 38 



36. Pattern in rings of red, black, and sometimes yellow ; no scale pits. 



Pliocercus (p. 109) 

 Pattern in stripes, uniform or with only a light neck ring 37 



37. Striped (sometimes not strongly) ; no scale pits — Rhadinaea (part) (p. 115) 

 No stripes whatever, either light or dark; uniform dark above, except 



for a light nuchal ring (absent in only one race) ; pits present. 



Diadophis (part) (p. 46) 



38. Uniform dark above except for a light nuchal collar ; uniform light 



(orange) below ; no scale pits ; eight supralabials Ehadinella (p. 119) 



Not colored as described ; pits present or not ; labials variable 39 



3.9. Black above and below, top of head lighter; no pits Amastridium (p. 31) 



Color not as described ; pits present or not 40 



40. Large dorsal si>ots ; snout pointed ; no loreal ; prefrontals and inter- 



nasals distinct Pseudoficimia (p. 112) 



No large spots on dorsal surface or, if present, prefrontals fused with 

 internasals on each side ; snout pointed or not ; loreal variable 41 



41. Red, black, and yellow rings about all or part of hody and tail, the 



remainder of which (if not all ringed) nearly unicolor. 



Scaphiodontophis (p. 28) 

 Color not as described 42 



42. Nine upper labials ; a pair of black dots on each ventral, near middle 



anteriorly but divei'ging laterally toward posterior part of body and 



tail ScapModontophis (part) (p. 28) 



Eight or fewer labials; venter not marked as described 43 



43. Striped ; no scale pits ; seven or eight supralabials ; a loreal ; nasal com- 



pletely divided ; temporals 1-1 or 1-2 ; snout normal ; head flattened. 



Bhadinaea (part) (p. 115) 

 No stripes, or only a dark line on vertebral scale row ; scale pits present ; 

 six or seven supralabials ; loreal sometimes absent ; nasal divided or 

 not ; temporals 1-2 ; snout pointed or produced ; head rounded 44 



44. Usually no preocular; nasal completely divided; tail long, with 85 or 



more subcaudals ; ventrals 174 or more Enulius (p. 61) 



A preocular ; nasal not or partly divided ; tail short, with not over 50 

 (46 maximum known) subcaudals; ventrals 150 or less (145 known 

 maximum) 45 



45. Posterior maxillary teeth not enlarged or grooved Conopsis (p. 45) 



Posterior maxillary teeth enlarged and deeply grooved Toluca (p. 143) 



