534 ZOOLOGY— BATRACHIANS AND REPTILES. 



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 Girard. — 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. adamanteus, 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. 



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

 14; 2 rows between them and 1he 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 : 



" G.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. 



U C. tiffris, 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 bands on 

 posterior two-thirds of body. — Deserts of Gila and Colorado. 



ll aa. Upper margin of canthus rostralis, with small scales like the others : 



u d. Prenasal hicontact with rostral; superciliary prolonged into a horn: 

 " G. cerastes, Haliowell. — 2 elongate preorbitals ; rostral broad 



