CROCODILIANS, LIZARDS, AND SNAKES. 1155 



middle ol" the orbit. Lubials eigliteen above, fifth and sixth largest; 

 seveiiteeu below. Dorsal rows of scales twenty-nine. Two external 

 rows small. Tail uniform black. Color roll sulphur, a series of 

 cliestnut-brown transverse lozenges, with exterior corners produced 

 to the abdomen. Centers of lozenges with one or two spots. l^>acli 

 scale but one color. A brown patch below and behind the eye. 



Head very broad in front; outline nearly rectangular. iJostral small. 

 Two internasal frontals; beliind these four i>lates, the exterior resting 

 on the superciliary; behind these two other plates, between and in con- 

 tact with the superciliaries. Anterior nasal subtriangular. Top of 

 head with numerous smooth subtuberculous scales. Suborbitals large, 

 extending to the anterior canthus. General aspect smoother than in 

 Crotali generally, scales rounded at the posterior apex, carinated but 

 slightly. 



(ieneral color above that of roll sulphur, beneath pale yellowish, pos- 

 teriorly very faintly clouded with brownish. Tail black. Anteriorly 

 the scutelhe are entirely immaculate. Along the back is a series of 

 transverse reddish or chestnut-brown lozenges embraced iu a width of 

 twelve or fourteen scales and four or five scales long, and with the 

 exterior angles produced to the abdomen. These lozenges are frames 

 with the outline generally one scale in width and with the centers of 

 the ground color; sometimes divided by a median line of brown, so as 

 to show two yellowish spots inside of the lozenges. The scales exterior 

 to the lozenges are rather lighter. Sometimes the brown rings and the 

 lozenges widen at the abdomen and indicate lateral spots of four scales; 

 at others, and especially anteriorly, the rings are obsolete, and the 

 browu is iu a dorsal series. Iu fact, for the anterior foui'th of the body 

 we have a dorsal patch of brown, showing alternately at successive 

 intervals one large yellowish spot and then a pair of smaller ones, 

 owing to the confluence of the successive lozenges. The superciliaries 

 and scales anterior to them, as well as a broad patch below and behind 

 the eye, light greenish brown. Tail uniform dark brown above, paler 

 beneath. Only one button with two necks, no rattle. 



A remarkable character of this species is that each individual scale 

 is ol' a uniform tint to its base, and does not show two colors, as in 

 other species. 



Cat. No. 1<S5; rows of scales, 29; j^astiostoges, 203; urostfgi's, 21; total lougtli, 

 1,097 lum. ; tail, 79 iimi. 



This large species is the only one within our political limits which 

 l)Ossesses the characters of the head scales found in the Neotropical 

 species. Among these it approaches nearest the G. hasULsvun Cope.' 

 That species has, however, well-defined dorsal rhombs, as in C. tcrriJicHS, 

 C. (((!(( iiiantcus, etc. Its habitat is southern New Mexico ami Arizona 

 and northern Souora and ijrobably Chihuahua. It is the largest and 



' Proc. Acad. Nat. Sci. Phila., 1861, i>. 160. 



