54. ZAMENIS. '381 



** Scales in 17 rows. 



t Snout moderately projecting, obtuse. 

 Third and fourth (rarely fourth and fifth) 

 labials entering the eye ; ventrals 160- 



190 ; subcaudals 74-104 5. constrictor, p. 387. 



Fourth and fifth labials entering the eye ; 



ventrals 184-197 ; subcaudals 110-128. 6. lineatm, ]}. 'dS'ii. 

 A single labial entering the eye ; ventrals 



185-202 ; subcaudals 111-113 7. men^ovari««, p. 389. 



ft Snout very prominent, rather pointed ; ventrals 

 180-203; subcaudals 85-99. 



13. spinalis, p. 394. 



ft. Frontal not or but slightly wider than the supraocular ; 

 ventrals 182-211. 

 A subocular below the prseocular ; two 

 . labials entering the eye ; subcaudals fp. 389. 



80-1 12 \ 8. flnrjdUformis, 



A subocular below the prneocular ; two 

 labials entering the eye ; subcaudals 



115-157 ' 9. fcmiatiis, p. 390, 



No subocular : three labials entering the [p. 392. 



eye; subcaudals 133-152 10. j^uh-herrimns, 



h. Portion of rostral visible from above as long as or a 

 little shorter than its distance from the frontal ; ven- 

 trals 175-20(5. 

 Three labials entering the eye ; subcaudals 



127-135 11. mexicanus, p. 392. 



One or two labials entering the eye ; sub- 

 caudals 75-108 12. qrahami, p. 393. 



2. Scales in 19 rows (rarely 17 in Z. gemoneiisis). 



a. Frontal not or but slightly wider than the supraocular, 

 more than once and a half as long as broad. 

 Tentrals rather indistinctly angulate late- 

 rally ; scales with two apical pits 14. r/emonensis, p. 395. 



Ventrals very distinctly angulate laterally; 



scales with a single apical pit 15. dcMii, p. 397. 



h. Frontal anteriorly considerably wider than the supraocular. 



«. Nine upper labials, two of which enter the eye. 

 Ventrals 214-262; subcaudals 113-145 . . 16. rJiodorJiachis, 



[p. 398. 

 Ventrals 199-211 ; subcaudals 82-119 .. 17. ventrimaculatus, 



[p. 399. 

 />. Nine upjier labials ; a subocular separates the eye from 

 the sixth labial 18. Icardiaii, p. 401. 



