1142 REPORT OF NATIONAL MUSEUM, 1898. 



eral borders are concave but vertical in adaptation to the prenasal plate ; 

 below it is slightly expanded; above it slightly truncates the other- 

 wise triangular internasals. The prefrontals have an open angle at the 

 junction of the superciliary and frontal scuta. The frontal is but little 

 wider than each superciliary and presents an open angle forward. 

 Posteriorly it has a parabolic and not an angular outline, and its aj)ex 

 is on a line with the posterior angles of the superciliaries, with which 

 it incloses a deep notch. Each parietal is about the size of the frontal ; 

 it is short and is broadly rounded behind. 



Both nasal scuta are higher than long, the postnasal the narrowest. 

 One loreal higher than long, entirely separating the postnasal and pre- 

 oculars. One or two small scales below it and in front of the one which 

 borders the pit. Two preoculars, the inferior sometimes divided into 

 a short posterior and a longer anterior. Superior labials, ten or gener- 

 ally eleven, separated from the front of the orbit by one scale, from the 

 rest of it by two scales. Temporals, except lowest two rows, keeled. 

 Three pairs of geneials separated by a groove; the anterior pair largest, 

 Gular scales smooth. Dorsal scales in twenty-one, sometimes twenty- 

 three, longitudinal rows, all carinated, the first and second rows slightly. 

 On the terminal fifth of the tail the urosteges are in two rows. The 

 rattle is a miniature of that of other rattlesnakes, and has a gradual 

 acumination of form. The gastrosteges are fewer in number than in 

 other species, ranging as low as one hundred and twenty-three. 



Ground color grayish ash of various depths, punctuated with dark 

 brown. A series of from thirty-eight to forty-five subcircular dorsal 

 blotches extending from head to tail, dark brown, each with a narrow 

 distinct yellowish border. Interval rather narrower than the spots 

 themselves. A broad band of purplish red passes from head to tail 

 through the blotches. On each side may be distinguished three series 

 of blotches, the first on the first and second lateral rows of scales and 

 j)artly on the abdominal scutelhu. The second, alternating with this, on 

 the second, third, fourth, and fifth rows of scales, and opposite the 

 dorsal series. The third, alternating with the second and the dorsal 

 series, on the fifth, sixth, seventh, and eighth rows of scales. The 

 latter series is dusky and obsolete; the others are uniform and dis- 

 tinctly black. 



The shape of the blotches is subjected to some variation, according 

 to individuals. Generally subcircular or slightly oblong, they become 

 sometimes a transversely elongated quadrangle, three times as long as 

 wide. Their shape varies, according to the region of the body on which 

 they are found. On the anterior third they are subquadrangular, an- 

 teriorly and posteriorly emarginated; on the middle region they elon- 

 gate, and toward the posterior third become nearly circular. Back- 

 ward of the anus the five or six blotches of that region extend on the 

 sides, without, however, meeting on the lower surface. The blotches 

 of the first lateral row are subquadrangular and a little smaller 



