76 



Key to the Native Families of Ophidia. 



Maxillary bones elongated, with a row of several teeth in each ; none 

 of these grooved or perforated ; no poison glands or fangs present. 



ColubridcB, p. 76. 



Maxillary bones each with a single erect, immovable poison fang, 

 which is grooved in front. No pit between eye and nostril. Body with 

 rings of black, red, and yellow. Elapidce, p. 121. 



Maxillary bones much shortened, bearing each a large, erectile poison- 

 fang, with a few supplementary fangs; these perforated and the func- 

 tional fang connected with the duct of a poison gland. A pit between 

 the eye and nostril. Crotalidce, p. 122. 



Family I. COLUBRID^. 



Figure 9, PI. 3. 



Form elongated. Head more or less distinct from the neck. Tail 

 tapering to a point. Head covered with large epidermal plates.* Max- 

 illary long, furnished with a row of conical, solid teeth. No poison 

 fangs or glands. Pupil circular. No j^it in front of eye. No rattle. 

 No anal spurs. 



Key to the Genera of the Family' Colubridoe. 



A. Anal plate divided. 



a. Dorsal scales not keeled, f 



b. Loral absent ; anteorbital present. Tantilla. 



bb. Loral present ; anteorbital absent, 

 c. Nasal single, pierced by nostril. 



Rows of scales 13. Carphoplm, p. 78. 



Rows of scales 19 ; two prefrontals. 



Abastor. Appendix. 

 Rows of scales 19 ; prefrontals united. 



Farancia, p. 79. 



cc. Nasals 2, with nostril between them ; rows of scales, 



15 or 17. Virginia, p. 80. 



*For plates illustrating the heads of North American species, see Volume X of the 

 Pacific Railroad Survey Report. 



t Sometimes in Coluler only the scales of the upper rows have keels, and occasionally 

 all may be smooth. 



