POISONOUS SNAKES OF NORTH AMERICA. 439 



warrant us in recognizing? it as a geographic subspecies even. The 

 character is an ancestral one, and its appearance may probably be 

 attributed to reversion. 



Geographical distribution. — Crotalus atr ox covers a considerable area, 

 embracing the arid portion of Texas, parts of southern New Mexico, 

 Arizona, and California, southward into Mexico. In western and 

 southern Texas, west of about the ninety- seventh meridian this species 

 appear to be the Rattlesnake, being apparently common in all suitable 

 localities. It does not appear to occur in the moist region of eastern 

 Texas, and as a matter of fact we do not know which form occupies 

 that region at all, whether C. adamanteus extends so far west as to 

 meet its western representative, G. atrox, or whether there is an actual 

 gap between the two species, occupied by neither. Toward the north. 

 Prof. Cope (Proc. Phila. Acad., 1S92, p. 336), has found it at the eastern 

 foot of the Staked Plain, about the head of the Colorado River, but he 

 did not meet with it on the Plain itself, nor north of the region men- 

 tioned. That it extends considerably farther north is proven, however, 

 by a specimen (Ko. 4225) in the National Museum, collected near the 

 western boundary of Texas, just south of the Canadian River and at 

 the northern foot of the Llano Estacado. 



Habits. — Very little has been written concerning the habits of G. 

 atrox, but in a general way they may be considered to be similar to 

 those of G. adamanteus, except that the former is apparently less 

 partial to water. Being a large and powerful snake, though not quite 

 so large as the Diamond Rattlesnake, it is capable of intiicting very 

 dangerous bites. 



The Red Diamond Rattlesnake. 



Crotalus atrox ruher," Cope. 



1892. — Crotalus adamanteus ruber, Cope, Proc. U. S. Nat. Mus., xiv, 1891, p. 690. 



Description.} — Rostral plate a little wider than high; plates of upper 

 side of canthers rostralis smaller tlian in other subspecies, the posterior 

 especially smaller than the anterior, and partly decurved laterally. 

 One loreal. Five rows of scales between orbit and labial; eight rows 

 between superciliary plates. Second pair of inferior labials with the 

 marginal portion cut off from the postsymphyseal portion. (Perhaps 

 an abnormality.) 



The color is light red, marked above with deep red spots. These are 

 of a longitudinal oval form anteriorly, but posteriorly they have a 

 diamond-shai^ed form. They have no distinct lateral borders, either 

 light or dark, but they are separated on the median line of the back bj- 

 a single row of yellow-tipped scales. Traces of brownish red indefinite 



- * From the Latin ruber, red, ruddy. 



t Original description by E. D. Cope, in Proc. U. S. Xat. Mus.,- xiv, 1891, p. 690, 

 from U. S. Nat. Mus., No. 9209; locality unknown. 



