1158 REPORT OF NATIONAL MUSEUM, 1898. 



baud generally preseut, which descends to the edge of the mouth 

 anterior to its angle, or canthus. 



This species presents greater variations than any other known, and 

 its subspecies have been regarded as species. I find transition from 

 one to the other of these forms, however, and they forbid recognition of 

 uiore than one species. This form ranges from the Atlantic to the 

 Pacific in the warmer parts of North America, and descends to Chi- 

 huahua and Cai)e St. Lucas to the southward in Mexico. This is the 

 largest and most formidable species of the genus, examples eight feet 

 in length having been reported to me from the Gulf coast of Florida 

 by Admiral McCauley, U. S. Is. 



The subspecies differ as follows : 



Entire top of head covered with irregular ilat scuta larger than the usual scales; 

 hody colors paler than tail bauds ; dorsal rhombs with truncated angles one ; loreal 

 plate C. a. scuhdatns 



Top of head with large plates on canthus rostralis, but scales elsewhere; two 

 loreal plates; dorsal rhombs complete, not paler than caudal bands; last caudal 

 band a broad ring C. a. adamantens. 



Top of head with plates on canthus and scales between; generally one loreal plate; 

 dorsal rhombs paler than bauds of tail, which is not black at end C. a. atrox. 



CROTALUS ADAMANTEUS SCUTULATUS Kennicott. 



Crofalns adamanteus scutidains CorE, Check-list N. Amer. Batr. Rept., 1875, p. 33; 

 I'roc. Amer. Phil. Soc, XXIII, 1886, p. 287; Report U. S. Geog. Survey W. of 

 100th Mcr., V, 1875, p. 607. 



Caudisona scutulata Kennicott, Proc. Acad. Nat. Sci. Phila., 1861, p. 207. — Cope, 

 Proo. Acad. Nat. Sci. Phila., 1866, pp. 307-309. 



Crotalus scutidatiis Boulengeu, Cat. Snakes Brit. Mus., 2d. ed.. Ill, 1806, p. 575. 



Crotahis salvini GCintiier, Biol. C. Amer., Rept., 1895, p. 193, pi. Lix, fig. A (accord- 

 ing to Bouleuger). 



Eostral triangular, nearly as wide as high. Two rather small inter- 

 nasal plates in contact; four prefrontals, the external the larger. 

 Space between superciliaries narrow, nlled with large flat plates. 

 Scales on the occiput large and frequently representing parts of parietal 

 plates. One loreal. Dorsal rows of scales twenty-five, the external 

 nearly smooth. Labials sixteen above, sixteen below. Three rows of 

 scales between the suborbitals and labials. Light stripe from angle of 

 eye to canthus rostralis above the labials, and another from before 

 the eye to the labials, as in G. a. atrox, but the rostral and space in 

 front of the pit and nostril not lighter than the crown. On the middle 

 third of the body a dorsal series of distinct rhomboids, margined with 

 whitish and with the lateral angles acute, much as in C. a. atrox or C. a. 

 adamanteus; the longitudinal angles sometimes perfect, at others trun- 

 cate or emarginate. Nineteen brown half rings, posteriorly narrow 

 and separated by wider light intervals than in C. a. lucifer. Eings on 

 the tail narrow, irregular, and quite black. 



This subspecies so closely resembles C. atrox that a description of 

 it must be comparative to some extent. The head is longer and nar- 



