10 CROTALUS. 



6. CrotalSSS B3:io2ossaiS, 13. & G. Muzzle broad ; rostral small. 

 Scales between superciliaries small, uniform, except the two anteiior. Two 

 frontal plates, four postfrontal. Two inter superciliary, all in contact. Five 

 rows scales between the labials and suborbital row. Middle row, not ex- 

 tending beyond the middle of the orbit. Labials 18 above, fifth and sixth 

 largest ; 17 below. Dorsal rows of scales 29. Two external rows small. Tail 

 uniform black. Color roll sulphur, a series of chestnut -brown transverse 

 lozenges, with exterior corners produced to the abdomen. Centres of lozenges 

 with one or two spots. Each scale but one color. A brown patch below and 

 behind the eye. 



One of the most strongly marked of all the species. Head very 

 broad in front; outline nearly rectangular. Rostral small. Two 

 anterior frontals ; behind these four plates, the exterior resting on 

 the superciliary; behind these two other plates, between' and in 

 oontact 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. 



General color above that of roll sulphur, beneath pale yellowish, 

 posteriorly very faintly clouded with brownish. Tail black. Ante- 

 riorly the scutelljB are entirely immaculate. Along the back is 

 a series of transverse reddish or chestnut-brown lozenges embraced 

 in a width of 12 or 14 scales and 4 or 5 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 

 centres 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 brown is in a dorsal series. In fact, for 

 the anterior fourth 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 suc- 

 cessive 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 



