382 COLTJBEID.E. 



y. Eigb.t upper labials 19. 



[p. 402. 



3. Scales in 21 or 23 rows ; two labials enter the eye. 



a. One prseocular (rarely divided), with a subocular below it ; 

 scales smooth. 



Nine upper labials ; subcaudals not more 



than 100 20. Jlorulentus, p. 402. 



Nine upper labials ; subcaudals more than 



100 21. gracilis, p. 404. 



Eight upper labials ; subcaudals less than 



100 22. fasciolatus, p. 404. 



6. Two prseoculars in addition to the subocular ; scales with 

 an obtuse or faint keel 23. ravergieri, p. 405. 



4. Scales in 23 or 25 rows, usually a single labial enters the 



eye. 



a. Two pra30culars in addition to the subocular. 



Scales obtusely or faintly keeled ; ventrals 



197-216 ; subcaudals 79-101 24. nummifer, p. 407. 



Scales perfectly smooth ; ventrals 219-228 ; 



subcaudals 107-119 25. socotrce, p. 408. 



6. One priBocular, with a subocular below it ; ventrals 214- 

 232 ; subcaudals 87-104 .... 26. algiras, p. 408. 



5. Scales in 25 to 29 rows ; eye usually separated from the 



labials by suboculars 27. hippocrepis, p. 409. 



6. Scales in 31 rows ; two labials entering the eye. 



28. dorri, p. 410. 



II. Praefrontals broken up into three or more shields ; eye separated 

 from the labials by suboculars ; anal entire. 



A. Scales in 25 to 33 rows ; 10 to 13 upper labials. 



Hostral as deep as broad or a little broader 



than deep 29. diadema, p. 411. 



llostral much deeper than broad, wedged in 



far between the internasals 30. arenarius, p. 413. 



B. Scales in 41 to 43 rows ; 14 or 15 upper labials. 



31. microlepis, ]). 413. 



As has been done for the genus Tropidonoius, a table is appended 

 showing the numbers of scales and shields in the different species, 

 with the object of facilitaticg the identification of specimens : — 



