4 COLUBRID.S. 



tftt Internasals fused with the pnefrontals, nasa* 

 fused with the first labial. 



87. Sympholis, II. p. 188. 



/3. Posterior maxillary teeth strongly enlarged and sepa- 

 rated from the rest by a very distinct interspace. 



* Scales with apical pits ; snout rounded or obtusely 

 conical. 



Scales forming longitudinal series ; no suboculars. 



75. Liophis, II. p. 126. 



Scales forming longitudinal series ; a series of suboculars. 



76. Cyclagras, II. p. 144. 



Scales disposed obliquely ; no suboculars. 



77. Xenodon, II. p. 144. 



** Scales with apical pits ; snout projecting, cunei- 

 form. 



Scales smooth, in 19 or 21 rows. 



78. Lystrophis, II. p. 151. 



Scales keeled, in 23 to 27 rows. 79. Heterodon, II. p. 153. 



*** Scales without pits ; snout obtuse ; head narrow. 

 80. Aporophis, II. p. 157. 



c. Longitudinal series of scales in odd numbers ; ventrals 

 with a suture-like lateral keel, and a notch on each 

 side corresponding to the keel. 



a. Scales of vertebral row not enlarged. 



Scales smooth ; subcaudals keeled and notched like the ventrals. 



67. Philothamnus, II. p. 98. 



Scales keeled ; subcaudals keeled and notched like the ventrals. 



68. Gastropyxis, II. p. 102. 



Scales keeled ; subcaudals without keel or notch. 



69. Hapsidophrys, II. p. 103. 



/3. Scales of vertebral row enlarged. 



64. DendropMs, II. p. 77. 



4. Palatine and pterygoid teeth absent or few ; maxillary bone 

 short, with 5 to 8 teeth. 



a. Maxillary teeth forming an uninterrupted series. 



Pupil round; snout projecting, obtuse. 



93. Oligodon, H. p. 233. 



Pupil vertically subelliptic ; snout with angular horizontal edge. 



94. Prosymna, II. p. 246. 



