SYNOPSES AND DESCRIPTIONS. dak 
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 Onychophidia; and without poison-secreting glands and 
fangs, as in the Toxicophidia. 
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 into 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. 
DIPSADIN AE. 
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. Seales 
imbricate, smooth, rarely keeled, generally the vertebral row larger. 
