11. lACHBSIS. . 531 



** Keels on the dorsal scales extending nearly to the 

 extremity. 



Scales in 29-35 rows; ventrals 167- 



188 ; suhcandals 31-51 7. alternatus, p. 541. 



Scales in 21-27 rows ; ventrals 168- 



182 ; subcaudals 41-53 8. neuwiedii, p. 542. 



Scales in 23-25 rows; ventrals 149- 



160 ; subcaudals 30-38 9. ammodytoides, p. 543. 



5. Upper head-scales all smooth ; dorsal scales not strongly 



keeled ; scales in 27 rows ; ventrals 196 ; subcaudals 



54 , 10. soanthograminus, 



[p. 543. 

 B. Subcaudals all or greater part single. 



1. Second upper labial forming the anterior border of the loreal 



pit ; scales in 25-27 rows ; ventrals 230-253 ; subcaudals 

 72-83 11. castelnaudi, p. 544. 



2. Loreal pit separated from the labials. 



a. Supraocular narrow, separated from its fellow by 7-10 

 series of scales ; scales in 23-27 rows ; ventrals 121- 

 134 ; subcaudals 26-36 .... 12. nummifer, p. 544. 



6. Supraocular large, separated from its fellow by 5-7 series 



of scales. 



•Snout not turned up ; rostral not deeper 



than broad ; scales in 21 rows ; ven- 

 trals 135-142 ; subcaudals 22-34 . . 13. godmani, p. 545. 

 ■Snout turned up at the end ; rostral once 



and one third to once and a half as 



long as broad ; scales in 25-27 rows ; 



ventrals 152-159 ; subcaudals 29-35. 14. lansbergii, p. 546. 

 ■Snout much produced above at the end ; 



rostral once and two thirds to twice as 



deep as broad ; scales in 23-25 rows ; 



ventrals 132-150 ; subcaudals 27-38 . 15. bracTiystoma, p. 547. 



H. Asiatic species ; subcaudals in two rows. 



A. Scales between the eyes smooth or obtusely keeled; gular 

 scales smooth ; first lower labial in contact with its fellow 

 behind the symphysial. 



1. Scales in 21-25 (rarely 27) rows ; ventrals 129-158 ; sub- 

 caudals 21-57 ; 5 to 9 series of scales between the supra- 

 oculars ; tail not prehensile. 



Supraoculars large, separated by 5 to 8 

 series of scales ; scales smooth or 

 feebly keeled ; canthus rostralis 



obtuse 16. montieola, p. 548. 



2ii2 



