1901.] NATURAL SCIENCES OF PHILADELPHIA. 17 



b"'. — Scales smooth : 



a^ — Loreal and preocular present: 



1 preocular; 1 nasal; color not green, 



CONTIA. 



1 preocular; 1 nasal j color green, 



LlOPELTIS. 



2 preoculars; 2 nasals, 



DiADOPHIS. 



6^ — Preocular absent: 



2 internasals; 2 nasals; size small, 



Virginia. 

 2 internasals; 1 uasal ; large; bluisli- 

 l)lack with red stripes, . . Abastor. 

 1 internasal ; 1 nasal ; large ; bluish- 

 black with red spots, . . Farancia. 

 1-2 or no internasals; 1 nasal; small; 

 brown, Carphophis 



c\ — Loreal absent: 



Nasal usually fused with first labial, 



FiCIMIA. 



Nasal usually fused with internasal, 



Chilomeniscus. 

 h. — Maxillary teeth longer behind; no interspace: 

 a' — Anal divided : 



Rostral normal, Zamenis. 



Rostral ^vith projecting edges, 



Salvadora. 

 h\ — Anal entire: 

 a". — 2 nasals: 



Rostral normal ; subcaudals divided 



Ophibolus. 

 Rostral projecting; subcaudals entire, 



Rhinochilus. 

 Ir. — 1 nasal, rostral projecting, 



Cemophora. 

 c. — Maxillary teeth longer behind; an interspace: 



a\ — Anal entire; 3-4 loi'eals; rostral with projecting 



edges, PflYLLORHYNGHUS. 



h\ — Anal divided; 1 loreal: 



Scales keeled; rostral recurved, 



Heterodon. 

 Scales smooth, with pits; 2 preoculars, 



Hypsiglena. 

 Scales smooth, without pits; 1 preocular, 



Rhadinea. 



