I88J.] GENERA SrCYDIUM AND LENTIPKS. 155 



II. Anterior mandibular teeth larger than the fol- 

 lowing. 



A. Teeth in the upper jaw bicuspid. 



a. Margin of the upper lip serrate 8. S. pugnans. 



B. Teeth in the upper jaw tricuspid. 



a. Scales subequal. 



a. First eight or ten rows on the occiput very 

 small. Head four and a hall in the length 

 (without the caudal). Caudal with a dark 

 horseshoe-like marginal band met by a 

 second passing along the middle i-ays from 



the root. D- 6^. A. ^ 9. S. tteniurum. 



jS. First two or three rows of scales on the 

 occiput very small. Head five and a half 

 in the length (without the caudal). Caudal 

 with a dark horseshoe-like marginal band 

 met by a second passing along the middle 



rays. D. 6—. A. yy 10. S. lagocephalum. 



y. Diameter of the eye is nearly equal to the 



interorbital space. D.6-;. A. r^ 11. S. ekgans*. 



£. Diameter of the ej-e equals the interorbital 

 space. The maxilla extends to the 

 vertical from the middle of the eye. 



T).-^. A. j^ 12. S.xanthurum*. 



6. Head and anterior portion of the trunk 

 scaleless. Diameter of the eye equals the 



interorbital space. D. 5-6y^. A. r^— yr 13. S. gi/mnauchen*. 



t,. A broad white band from the tip of the 

 snout to the root of the caudal, below 

 which is a longitudinal row of large 

 black spots 14. S. albo-tmniatum*. 



b. Scales on the middle of the trunk larger or 



much larger than those on the anterior 

 paris and tail. 

 a. Upper lip with a slight median cleft ; 



caudal much shorter than the head, with 



a black horseshoe-like marginal band 



met by a second passing along its middle 



rays ; the diameter of the eye is one third 



of the interorbital space. D. 6tt. A. rr. 



L. trans. 15 15. 8. micrurum. 



/3. Tipper lip without median cleft ; the last 

 ray of the dorsal much produced, extend- 

 ing past the base of the caudal. Colour 



uniform black. D. 6t-t. A. rr. L. trans, 



16 Ifi. S. nigrescens. 



y. Upper lip with a deep median cleft, and 

 two round lateral notches below the 



nostrils. D. 6^. A. ~. L. trans. 13 ... 17. S. stimpsoni. 



S. Upper lip with a slight median cleft ; 

 caudal longer than the head, olive with a 

 yellow margin ; diameter of the eye half 

 the interorbital space ; the maxilla ex- 

 tends to the vertical from the anterior 



11* 



