534 ZOOLOGY BATRACHIANS AND KBPTILES. 



in Southern Arizona, which was probably this species, but he 

 was unable to preserve them ; the rattle and tail showing them 

 to belong to this division of the genus. 



" C. atrox, Baird and Girarcl. Scales 25-7 rows; labials 

 15 ; muzzle with small scales above : yellowish, with a dorsal 

 series of completely yellow edged, brown rhombs; yellow band 

 from supercilian above angle of mouth; tail black ringed. 

 Texas and Sonora. 



" C. adainanteiis, Beauvois. Scales 27 rows ; labials 15-16 ; 

 muzzle above with small scales, acuminate : brown, with three 

 series of brown, yellow edged, complete rhombs, the median 

 larger, only separated by their yellow margins ; a yellow line 

 from supercilian to angle of mouth. Florida and Georgia. 



" C. horridus, Linn. Scales 23-5, all carinate; labials 12- 

 14 ; 2 rows between them and the orbit : light line from 

 superciliary plate to angle of mouth ; two series of dorsal 

 rhombs, confluent except on the anterior part of the body, form- 

 ing transverse zigzag blotches ; tail black. Eastern District of 

 North America. 



"bb. One equilateral broad or depressed rostral: 



"C.enyo, Cope. Scales 23 rows; superior labials 13; super- 

 ciliaries separated by 6 rows ; scales on muzzle small : above 

 yellow, with a median series of small transverse rhombs, which 

 are prolonged into vertical lateral black bars ; former median 

 and longitudinal on neck ; light line to above canthus oris. 

 Lower California. 



"C.ttf/rts, Kennicott. Scales 21-3 rows, numerous smooth 

 plates on top of muzzle, rostral lower; labials 14, separated by 

 2 rows from orbit ; superciliary space wide : yellowish ash, with 

 small dorsal blotches on anterior one-third, and cross bauds on 

 posterior tAvo-thirds of body. Deserts of Gila and Colorado. 



u aa. Upper margin of canthus rostralis, with small scales like tlic others : 



"d. Prenasali-'.i contact with rostral; super ciliary prolonged into a horn: 

 " C. cerastes, Haliowcll. 2 elongate preorbitals; rostral broad 



