HETERODON. 63 



the angle of tlie mouth across the last labial. Behind this a much 

 broader yellowish band, continued without interruption into the neck 

 behind the angle of the mouth. In 11. nasicus the most conspicuous 

 feature is a narrow white band, much narrower than the darker patch 

 before and behind it. The dark patch, to the angle of the mouth, 

 is much broader, continuous as it were, with the broad bar between 

 the middle and anterior light lines, which corresponds with the nar- 

 row black line of H. simus. The other distinguishing features are 

 evident. The three dark patches behind the head are much as in 

 H. simus. 



In the larger specimens from Sonora and the Copper Mines, the 

 ground-color is yellowish gray, each scale minutely punctate with 

 brown. The blotches are all obsolete, only one dorsal and two lateral 

 on each side being defined by darker shades. The blotches on the 

 sides of the abdomen are wanting, but the black in the middle is 

 strongly marked. The other characters, however, are preserved, 

 except that the exterior row of dorsal scales is more or less carinated. 

 Rio Grande. 138+1. 45. 23. 7f. U. Gen. S. Churchill. 



RedRiver,Ark. 148+1.40.23. 12. U. { ^'^^'cLtlZ*^ 



Ft.Webster Santa | ^ ^^ ^S. 21. 2h Col. J. D. Graham. 



Rita del Gohre. ) 

 Sonora, Mex. !l50+1. 39. 23. 24. 3. « 



A specimen from California has the rostral rather less developed, 

 and four irregular plates on top of head. The coloration differs in 

 having the light transverse intervals between the dorsal blotches 

 narrower, especially posteriorly. 

 California. 137+2. 48. 23. 22}. 4. Dr. Wm. Gambel 



