356 KANSAS UNIVERSITY SCIENCE BULLETIN. 



Order OPHIDIA. 



Body elongated, slender ; covered with scales. Limbs want- 

 ing (vestigial hind limbs present in some species). Mandibles 

 loosely articulated, quadrate long and freely movable. Shoul- 

 der girdle absent. No eyelids or external organs of hearing. 



KEY TO FAMILIES. 

 No pit between eye and nostril. No erectile fangs. Pupil of eye 



round CoLUBRIDyE. 



Pit between eye and nostril. Erectile fangs. Pupil of eye elon- 

 gated, vertical Crotalid.e. 



COLUBRID.a;. 

 I. — Dorsal scales carinated. 

 a. — Anal entire. 



Scales in 27-33 rows Pi/yoph is. 



Scales in 1723 rows Eutacnia. 



Scales in 19 rows. One nasal Tropidoclonium. 



b. — Anal divided. 



1. — Loreal present. 



Scales in 17 rows. One nasal Ci/clophis. 



Scales in 23-25 rows. Rostral large, recurved. . . Heierodnn. 



Scales in 19-29 rows. Gastrostegee less than 170 Natrix. 



Scales in 27 .3.") rows. Gastrosteges more than 170. . . Coluber. 



2. — Loreal absent. Scales in 15-17 rows Storeria. 



II. — Dorsal scales smooth. 

 a. — Anal entire. 



Urosteges in two series Ophibrihis. 



Urosteges undivided Rhiiiovhilus. 



b. — Anal divided. 



Scales in 13 rows. One nasal. No anteorbital Carphophioj)^. 



Scales in 15-17 rows. A pale ring on the neck DiadnpJiis. 



Scales in 15 rows. Color green Liopellis. 



Scales in 15-19 rows Zomenii'. 



Scales in 15 rows. No loreal Tcintilla. 



Scales in 13-17 rows. One nasal. Anteorbital present Contia. 



CROTALID.ff:. 



I. — Rattle present. 



1. — Top of head with plates Sish-uriis. 



2. — Top of head with scales Crota/iis. 



II. — No rattle present Ancistrodon. 



