54, ZAMENIS. 381 
** Scales in 17 rows. 
+ Snout moderately projecting, obtuse. 
Third and fourth (rarely fourth and fifth) 
labials entering the eye; ventrals 160- 
190; subcandals 74-104 ............ 5. constrictor, p. 387. 
Fourth and fifth labials entering the eye; 
ventrals 184-197; subcaudals 110-128. 6. lineatus, p. 388. 
A single labial entering the eye; ventrals 
185-202; subcaudals 111-113 ...... 7. mentovarius, p. 389. 
tt Snout very prominent, rather pointed ; ventrals 
180-203; subcaudals 85-99. 
13. spinalis, p. 394. 
fA. Frontal not or but slightly wider than the supraocular ; 
ventrals 182-211. 
A subocular below the preocular; two 
labials entering the eye; subcaudals [p. 389. 
Raises wi gue < vos 5 caciclbpav dpa 8. flagelliformis, 
A subocular below the preocular; two 
labials entering the eye; subcaudals 
EES Diiwt cue cess esisnteacea ss 9. teniatus, p. 390. 
No subocular; three labials entering the [p. 392. 
eye; subcaudals 133-152............ 10. pulcherrimus, 
b. Portion of rostral visible from above as long as or a 
little shorter than its distance from the frontal; ven- 
trals 175-206. 
Three labials entering the eye ; subcaudals 
RUE ys Aaa a's 0.9’ a's » Hama wares 11. mexicanus, p, 392. 
One or two labials entering the eye; sub- 
caudals 75-108... 2.2... .20.cceeees 12. grahami, p. 393. 
2. Scales in 19 rows (rarely 17 in Z. gemonensis). 
_a@. Frontal not or but slightly wider than the supraocular, 
more than once and a half as long as broad. 
Ventrals rather indistinctly angulate late- 
rally; scales with two apical pits...... 14. gemonensis, p. 395. 
Ventrals very distinctly angulate laterally ; . 
scales with a single apical pit ........ 15. dahlii, p. 397. 
b. Frontal anteriorly considerably wider than the supraocular. 
«. Nine upper labials, two of which enter the eye. 
Ventrals 214-262; subcaudals 113-145.. 16. rhodorhachis, 
[p. 398, 
Ventrals 199-211; subcaudals 82-119 .. 17. ventrimaculatus, 
[p. 399. 
jf. Nine upper labials ; a subocular separates the eye from 
the sixth labial .......... 18. karelinii, p. 401. 
