112. arRactus. 301 
B. Loreal at least twice as long as deep. 
1. Two pairs of chin-shields ; usually a single postocular. 
Scales in 15 rows; prefrontals as long 
as broad ; eight upper labials ...... 4, vittatus, p. 304. 
Seales in 17 rows; prefrontals as long 
as broad ; six upper labials ........ 5. latifrontalis, p. 304. 
Seales in 17 rows; prefrontals much 
longer than broad; six upper labials. 6. longiceps, p. 305. 
2. A single pair of moderately broad chin-shields ; anal entire. 
a. Scales in 17 rows. 
a. Two postoculars. 
* Prefrontals a little broader than long. 
Ventrals 140; rostral broader than deep ; 
Sia uppor labial: 2588 oe ed oie cee we 7. permianus, p. 305, 
Ventrals 143-158 ; rostral broader than 
deep ; seven upper labials ........ 8. guentheri, p. 305, 
Ventrals 175-191; rostral nearly as 
deep asbroad ; seven upper labials .. 9. bocourti, p. 306. 
** Prefrontals as long’ as broad; ventrals 146-161. 
Rostral once and a half as broad as deep ; 
frontal slightly broader than long .. 10. maculatus, p. 306. 
Rostral nearly as deep as broad; frontal 
as long as broad or a little longer.... 15. crassicaudatus, p. 310. 
*** Preefrontals a little longer than broad. 
Frontal as long as broad or slightly 
longer than broad; loreal twice and 
a half to thrice and a half aslong as 
broad; ventrals 163-182 .......... 11. major, p. 307. 
Frontal a little longer than broad ; loreal 
twice as long as broad; ventrals 160. 12. asthmicus, p. 307. 
Frontal as long as broad or a little 
broader than long; loreal twice and 
a half to thrice and a half as long as 
deep; ventrals 143-160 .......... 13. badius, p. 308. 
B. A single postocular ; frontal longer than broad; eight 
uppenlabials: 0s... 14. torquatus, p. 309. 
b. Scales in 15 rows. 
a. Snout obtuse; ventrals 150-172; subcaudals 16-32. 
* Hight upper labials. 
Prefrontals longer than broad; both 
postoculars in contact with temporal. 16. duboisi, p. 310. 
Preefrontals as long as broad ; lower post- 
ocular not in contact with temporal.. 17. occipitoalbus, p. 310. 
