170 BULLETIN 187, UNITED STATES NATIONAL MUSEUM 



2. Yellow rings in the triads and on tail split by a very narrow black ring 



(interrupted or not) ; light head ring very narrow, interrupted 



dorsally elegans elegans* 



Yellow rings not split ; light head ring broad, uninterrupted laticollaris 



3. Entire supralabial border light, or a distinct light spot on tip of snout — 4 

 Black on anterior part of head reaching labial border ; no light spot on 



tip of snout 8 



4. Black rings on body generally over 29 (minimum 28) ; scales in red 



areas not uniformly black-tipped affinis apiatus 



Black rings on body 28 or less ; species with higher numbers have the 

 tips of the red scales uniformly black-tipped 5 



5. Scales in red areas not or very feebly black-tipped 6 



Scales in red areas nearly or quite uniformly black-tipped 8 



6. Black rings on body less than nine diastema michoacanensis 



Black rings on body more than nine 7 



7. Ventrals 191 to 210 in males, 207 to 220 in females — diastema diastema 

 Ventrals 208 to 216 in males, 222 to 237 in females diastema distans 



8. Red bands narrow (not over six scale lengths), completely interrupted 



dorsally by a broad black area extending laterally to second or third 



scale row ephippifer 



Red rings not completely interrupted dorsally 9 



9. Scales in red areas not black-tipped or otherwise marked with black— _ 10 

 Scales in red areas black-tipped or black-spotted 12 



10. Ventrals 210 to 220 in males (6), 226 to 230 in females (5) ; black rings 



usually including three or four ventrals, 11+4 to 24+7 (usually over 

 17+4) on body and tail ; yellow rings distinct, covering one and one-half 



scale lengths dorsally browni* 



Ventrals 196 to 207 in males, 213 to 224 in females ; black rings narrower, 

 including 2 or 3 ventrals, 12 to 20 on body, 3 to 7 on tail; yellow rings 

 narrow or broad 11 



11. Yellow rings broader, covering 1% to 2 scale lengths dorsally ; black 



rings 12+3 (female) or 12+4 (male) in known specimens; prefrontals 

 in contact with or narrowly separated from labials. 



nigrocinctus ovandoensis* 

 Yellow rings very narrow, frequently obsolete vent rally, covering less 

 than one scale length dorsally ; black rings 15+4 to 20+5 in females, 

 14+5 to 18+7 in males ; prefrontals broadly separated from 

 labials nigrocinctus zunilensis* 



12. Body with about 40 black spots restricted to dorsum bernadi 



Body with not over 28 black rings or (rarely) spots 13 



13. Black rings covering six or more scale lengths middorsally (excluding 



anterior two or three) 14 



Black rings covering five or less scale lengths middorsally (excluding 

 anterior two or three) 15 



14. Black rings six to nine latifasciatus* 



Black rings more numerous fulvius tenere 



15. Nuchal black band covering eight scale lengths or more ; black bands 



on body seven to ten nuchalis nuchalis* 



Nuchal black band covering less than eight scale lengths; black bands 

 on body not known to be less than 11 16 



16. Black rings broader, covering three to five scale lengths middorsally 17 



Black rings narrower, covering two or three scale lengths middorsally 19 



