442 REPORT OF NATIONAL MUSEUM, 1893. 



Scales on the top of the head less carinated. Scales between super- 

 ciliaries smaller and more numerous, 5 or C in number instead of 4. 

 Two lateral rows of scales smooth, first, second, and third gradually 

 increasing in size. Scales more linear than in C. atrox. 



General color yellowish brown with a series of subquadrate dark 

 blotches, with the corners rounded and the anterior and posterior sides 

 frequently concave, the exterior convex (fig. 53). These blotches are 10 

 or 11 scales wide and -lor 5 long, lighter in the center, and margined for 

 one-third of a scale with light yellowish. The intervals along the back 

 light brown, darker than the margins of the blotches. Anteriorly the 

 interval between the dark spots is but a single scale; posteriorly it is 

 more, becoming sometimes 2 scales, where also the spots are more 

 rhomboidal or lozenge shaped ; nearer the tail, however, they become 

 transversely quadrate. The fundamental theory of coloration might 

 be likened to that of Crotalus adainaiiteus, viz, of 40 or 50 light lines 

 decussating each other from opposite sides; but the angles of decus- 

 sating, instead of being acute, are obtuse, and truncated or rounded otf 

 throughout. Along the third, fourth, an<l fifth lateral rows of scales 

 is a series of indistinct brown blotches covering a space of about 4 

 scales and falling opposite to the dorsal blotches; between these 

 blotches, and opposite to the intervals of the dorsal blotches, are others 

 less distinct. Along the fifth, sixth, seventh, and eighth rows is a 

 second series of obsolete blotches, each covering a space of about 4 

 scales, and just opposite the intervals between the dorsal spots. Tlie 

 dorsal and lower series are separated by an interval of 3 scales, this 

 interval light brown. Beneath the color is dull yellowish, and 10 or 13 

 darker half rings are visible on the tail. 



In point of coloration the principal features, as compared with C. 

 atrox, lie in the dorsal blotches, being disposed in subquadrate spots 

 instead of subrhomboids; the intervals thus forming bands across the 

 back perpendicular to the longitudinal axis. This tendency to assume 

 the subquadrangular pattern has broken up thechainwork into isolated 

 portions, as in Coluber eximius or Crotalophorus tergcminus {Sistnirus 

 calenatus). The intervals of the dorsal blotches are wide and darker in 

 the middle, while in C. atrox they are narrow, not linear, and unicolor. 

 The sides of the head (fig. 59) present the usual light stripe from the 

 posterior extremity of the superciliary; it passes, however, to the angle 

 of the jaw on the neck, along the second row of scales above the labials. 

 A second stripe passes in front of the eye to the labials, widening there, 

 A small, light vertical bar is seen below the pit and another on the 

 outer edge of the rostral. On the superciliaries are seen two light trans- 

 verse lines inclosing a space nearly one-third of ihe whole surface. In 

 C. atrox there is a single median line. Sometimes, as in C. atrox, the 

 single blotches on the nape are replaced by two elongated ones parallel 

 to each other. 



