SYNOPSES AND DESCRIPTIONS. 11 



ACACOPHIDIA. 



Head and tail more distinct from the body, and eyes and teeth more 

 perfectly developed than in the Scolecophidia; without claws at the side of 

 the vent, as in the Onycliophidia; and without poison-secreting glands and 

 fangs, as in the ToxicopMdia. 



This group includes all the common, non-venomous snakes of the ground, 

 trees, or fresh waters. It contains but a single family. For convenience 

 this is divided info subfamilies, nearly corresponding to what have hereto- 

 fore been accepted as families, and for which the old names have been 

 retained. 



COLUBRIDAE. 



Elongate, tapering, compressed; head broad; pupil generally elliptical 



Dipsadinae. 

 Moderately slender, subcylindrical ; head moderate ; pupil elliptical 



SCYTALINAE. 



Slender, long; head long, narrow; eyes large; pupil round 



Dendrophinae. 



Fusiform, slender to stout ; head broad behind ; posterior maxillary teeth 

 usually larger; scales generally keeled Natricinae. 



Elongate, tapering to head and tail; head distinct from the neck, mod- 

 erately broad; crown-shields regular; loreal usually present; teeth 



smooth COLUBRINAE. 



Subcylindrical; head more or less distinct, short, shields commonly regu- 

 lar; scales rarely keeled Coronellinae. 



Cylindrical ; head short, rather indistinct ; usually some head-shields united ; 

 scales smooth or keeled Calamarinae. 



dipsadinae. 

 Tree snakes. Bodies more or less elongate and compressed, tapering to 

 head and tail; head large, distinct, somewhat triangular, broad behind, 

 depressed, muzzle broad and rounded ; tail short to long and slender. Eye 

 large to very large, pupil generally elliptical. Nostrils lateral. Teeth 

 varying much. In the majority of the species the posterior maxillary 

 teeth are longer and grooved. Head-shields nine, short, broad. Scales 

 imbricate, smooth, rarely keeled, generally the vertebral row larger. 



