wn 
a — = j —_— oil’ a _——_ 7 a - ee  e 7 a a4 
* - ~— 
178 COLUBRIDR, 
Scales keeled, without pits; nostril in a single nasal. 
8. Xenochrophis, p. 191. 
2. Maxillary teeth minute posteriorly, much larger ante- 
riorly ; eye rather large, with round pupil. | 
Renee mecled .. 0... 03. pets 9. Prymnomiodon, p. 192. 
* 8. Posterior maxillary teeth longest; mandibular teeth sub- 
eaual; eye moderate or large, with round pupil; a pair 
of internasal shields. 
a. Scales forming longitudinal series throughout the body. 
Maxillary teeth 18 to 40, forming a continuous series. 
10. Tropidonotus, p. 192. 
Maxillary teeth 14 to 22, the last two very large fangs separated — 
from the rest by an interspace ; snout rounded; scales keeled. 
11. Macropisthodon, p. 265. 
Maxillary teeth 12 to 14, the last two very large fangs separated 
from the rest by an interspace; snout pointed, projeccing; scales 
smooth ...... ale akin Ioasgre ne eoee 12. Lioheterodon, p. 268. 
b. Scales disposed obliquely on the anterior part of the 
body. 
Maxillary teeth 20 to 28 ........ 13. Pseudoxenodon, p. 270. | 
4. Posterior maxillary teeth longest; eye moderate or small, 
with round pupil; a single internasal shield. 
Mandibular teeth subequal ; nostril in a semidivided nasal; scales 
without pits (,..5 0630050000. 14. Helicops, p. 272. 
Mandibular teeth decreasing in size posteriorly ; nostril between two 
nasals ; scales with apical pits .. 15. Hydrathiops, p. 280. 
5. Maxillary teeth subequal; mandibular teeth equal or an- 
terior somewhat enlarged; eye small or rather small, 
' with round or vertically elliptic pupil. 
4 a. Labial shields not entering the nostril ; subcaudalsin two 
rows. i 
I _ a. Maxillary bone extending forwards beyond the pala- 
F) tines, 
* Scales keeled; a preocular; nostrils on upper surface 
of snout. 
Maxillary teeth strong, abeut 30 .. 16. Tretanorhinus, p. 281. 
7 Maxillary teeth small, 20 to 25 .. 17. Opisthotropis, p. 283. 
** Scales keeled; one or two preoculars ; nostrils 
lateral. 
Maxillary teeth 14 to 18 ..)...... 18. Ischnognathus, Pa 
é _ 
ao 
t , a 
