40 COLUBEID^. 



a pair of enlarged, grooved fangs ; anterior mandibular teeth 

 longest. Head distinct from neck ; eye large, witli vertical pupil. 

 Body more or less compressed ; scales smooth, with apical pits, in 

 17 to 25 rows, the scales of the middle row slightly, if at all, 

 enlarged ; ventrals obtusely angulate laterally. Tail moderate or 

 long ; subcaudals single or paired. Hypapophyses developed 

 throughout the vertebral column. 

 Madagascar; Comoro Islands. 



Synopsis of the Species. 



J. Scales in 17 or 19 rows j internasals much shorter than the 

 prasfrontals. 



A. Scales in 17 rows ; ventrals 187 ; subcaudals 67 pairs. 



1. guentheri, p. 40. 



B. Scales in 17 rows ; ventrals 228-276. 



Posterior chin-shields a little shorter than 



the anterior, and in contact with each 



other ; ventrals 229-248 ; subcaudals 



107-122, all or greater part in pairs . . 2. granuUeeps, p. 41. 

 Posterior chin-shields larger than the 



anterior and in contact with each other ; 



ventrals 228 ; subcaudals 110, greater 



part in pairs 3. inomatus, p. 42. 



Posterior chin-shields shorter than the 



anterior and separated by scales ; ven- 

 trals 255-276 ; subcaudals 93-116, all 



or greater part single 4. gaimardii, p. 42. 



C. Scales in 19 rows ;. ventrals 243; subcaudals 126, single. 



5. macidatus, p. 43. 



II. Scales in 21 to 25 rows ; internasals nearly as long as, or a 

 little longer than, the preefrontals. 



A. Loreal separated from the eye by the prseocular ; subcaudals 



152-159, single. 



Posterior chin-shields large and in contact 



with each other ; ventrals 225-236 .... 6. arctifasciatus, p. 43. 

 Posterior chin-shields very small or absent ; 



subcaudals 251-265 7. variahilis, p. 43. 



B, Loreal entering the eye ; ventrals 226 ; subcaudals 106 pairs. 



8. hetsileanus, p. 44. 



1. StenopMs guentheri. (Plate IV. fig. 1.) 



Eostral twice as broad as deep, scarcely visible from above ; 

 internasals nearly as long as broad, much shorter than the prae- 



