20 BULLETIN 114, UNITED STATES NATIONAL MUSEUM. 



q ^ Whitish cross bands little if any widened on 

 the lower rows of dorsal scales, and the scale 

 rows more than 17 on the anterior portion of 

 the body, 

 r^ Red scales usually tipped with black. 

 s^. Snout black, with usually a light transverse 

 bar on or near the prefrontals; two tem- 

 porals in the first row; caudals usually 



not less than 49 polyzonn, p. 139, 



(Southern Mexico to Costa Rica.) 

 §2. Snout yellowish with transverse black spots; 

 a single, anterior temporal, or, if two, the 

 upper much the smaller; caudals not m.ore 



than 49 micropholis, p. 149. 



(Panama to Colombia and Ecuador.) 

 r'^. Red scales not tipped with black. 



i^. Whitish annuli usually more than 30; 

 snout black. 

 u^. Ventrals more than 200; black rings 

 often meeting across the red dor- 

 sally multicincta, p. 222. 



(California.) 

 u^. Ventrals less than 200; black rings not 

 meeting across the red dorsally. 

 ruthveni, p. 221. 

 (Southern Mexico.) 

 t^. Whitish annuli less than 30. 



v^. Dorsal red areas usually continuous 

 across the belly; snout whitish, 

 specked with black. 

 w^. Ventrals usually more than 210 



(199 to 231) nelsoni, p. 155. 



(Western Mexico.) 

 iv"^. Ventrals usually less than 200, 



(180 to 212) amaura, p. 172. 



(Lower Mississippi Valley.) 



v^. Spaces on belly between the yellow 



rings filled with black; snout 



totally black, or only very slightly 



lightened on the top or sides. 



x^. Yellowish rings 19 to 25; black 



spaces on belly usually longer 



than the intervening yellow 



ones annulata, -p. lo9. 



(Plateau region of southern 

 Mexico north to extreme south- 

 ern Texas.) 

 x^. Yellow rings 25 to 40; black 

 spaces on belly usually shorter 

 than the intervening yellow 



ones gcntUis, p. 165. 



(Texas to South Dakota, west 

 to Utah and Arizona.) 



