280 



COLUBRIDjE. 



e". Eye rather small, moderate or 



a. Maxillary teeth few ( to 12), 

 very strongly enlarged pos- 

 teriorly ; eye rather small; 

 rostral shield large. 



a'. Pterygoids toothed 



/3'. Pteiygoids toothless 



ft. 12 or more teeth in each max- 

 illary, increasing in size pos- 

 teriorly. 



a'. Body moderate, not com- 

 pressed ; no subocular ; eye 



rather small 



ft'. Body slender ; a subocular 

 below the prajocular ; longi- 

 tudinal rows of scales in odd 



numbers 



y'. Body slender; longitudinal 

 rows of scales in even 



numbers 



y. 15 or more teeth in each max- 

 illary, subequal in length, 

 a'. 40 to GO teeth in each max- 

 illary ; -scales in 17 rows . . 

 /3'. 13 to 30 teeth in each max- 

 illary. 



a". Scales in 15 to 19 rows, 

 without apical pits, verte- 



brals not enlarged 



ft". Scales in 19 to 27 rows, 

 with apical pits, verte- 



brals not enlarged 



y' 1 . Scales in 17 rows, without 

 apical pits, of vertebral 



row enlarged 



1>, Posterior border of ventral shields with 

 a notch on each side corresponding to 

 a suture-like lateral keel ; scales in 

 13 or 15 rows. 



'. Maxillary teeth equal in length ; 



scales of vertebral row enlarged . . 



&'. Anterior maxillary teeth longest; 



vertebral scales not enlarged .... 



B. Aquatic or seniiaquatic Snakes, with the 



hypapophyses developed throughout the 



vertebral column, and very small nasal 



bones. Scales usually keeled. 



a. Posterior maxillary teeth longest. 



'. Scales on the anterior part of the 



body disposed obliquely, narrow 



and much imbricate 



//. Scales forming straight longitudinal 

 series ; two internasals 



SIMOTES, p. 300. 



OlJfJODON, p. 317. 



COHONELLA, p. 308. 



ZAMENIS, p. 323. 

 ZAOCYS, p. 329. 



POLYODOXTOPHIS, p. 301. 



ABL.ABES, p. 304. 

 COLUBEB, p. 330. 

 XENELAPHIS, p. 336. 



DENDROPHIS, p. 337. 

 DENDREL APHIS, p. 339. 



PSEUDOXEXODON, p. 340. 



TROPIDONOTUS, p. 341 . 



