412 COLTJBEID^. 



Synopsis of the Species. 



I. Seven upper labials, fourth, entering the eye ; frontal very 

 narrow ; ventrals 167-182 1. surinamensis, p. 414. 



n. Six upper labials, second and third entering the eye ; snout 

 narrow ; ventrals 209 2. heterocMlus, p. 414. 



III. Seven upper labials, third and fourth entering the eye. 



A. Seventh upper labial very small ; rostral large, its upper 

 Y portion nearly as long as its distance from the frontal; 



internasals nearly as long as the praefrontals ; ventrals 215- 

 241 ; subcaudals 21-29 3. euryxanth/us, p. 415. 



B. Seventh labial well developed ; rostral moderate, just visible 



from above ; internasals much shorter than the praefrontals. 



1. First lower labial in contact with its fellow ; posterior 

 nasal not reaching the praeocular ; ventrals 191 ; sub- 

 caudals 23 4. gravenhorstii, p. 415. 



_ 2. First lower labial in contact with its fellow; posterior 

 nasal in contact with the preeooular. 



a. Eye nearly as long as or a little longer than its distance 

 from the mouth ; frontal as long as or slightly shorter 

 than the parietals, which are not longer than their 

 distance from the internasals ; ventrals 189-227. 



o. Frontal once and one third to once and two thirds as 

 long as broad. 



* Frontal longer than its distance from the end of the 

 snout ; anterior chin-shields as long as or a 

 little shorter than the posterior. 



Subcaudals 37-54 ; temporals 1 + 1 ... . 5. langsdorffli, -p. 416. - 

 Subcaudals 39-43 ; temporals 1 + 2. .'. . 6. bucMeyi, p. 416. 

 Subcaudals 29 ; temporals 1 + 1 7. anomalus, p. 417. 



** Frontal as long as its distance from the end of the 

 snout ; anterior chin-shields shorter than the 

 posterior. 



Subcaudals 16-23 ; rostral a little 



broader than deep , 8. heterozonus, p. 417. 



Subcaudals 29-47 ; rostral much broader 



than deep 9. elegatis, p. 418. 



/3. Frontal not or but slightly longer than broad ; nearly 

 twice as broad as the supraocular ; j-ostral little if at 

 all broader than deep ; subcaudals 29-45. 



Temporals 1 + 1 ; third upper labial not 



or but scarcely larger than fourth . . 10. annellatits, p. 418. 



