354 REPTILES OF THE WORLD 



bordered with light yellow, extends along the back. 

 The species ranges from Mexico, through Central 

 America, thence well over South America. The South 

 American phase is much the handsomer, having a pair 

 of vivid longitudinal bands on the neck; this marking 

 is utterly lacking on the Mexican and most of the Cen- 

 tral American examples. This species has a very small 

 head, while the scales of South American specimens are 

 so coarsely keeled as to resemble the scalation of the 

 bushmaster, Lachesis mutus. The length of an adult 

 is up to seven feet. 



As a near ally of the South American rattlesnake 

 it is appropriate to mention a strange specimen de- 

 scribed by the author in 1904 as a new species. It was 

 taken inland from Managua, Nicaragua, in a dry, sandy 

 region, and was named the Gray Rattlesnake, C. 

 pulvis. The scalation is coarse and of a uniform blue- 

 gray like pumice dust. It is slightly over a yard long, 

 though it appears to be full grown, as the segments of 

 the rattle are of a uniform size. This type specimen 

 has been presented to the Museum of Comparative 

 Zoology, at Cambridge, Massachusetts. 



In the United States the rattlesnakes exhibit a great 

 variety of pattern but we have several species with the 

 rhomb-like markings like the South American serpent. 

 Largest and most dangerous of the North American 

 species, the Diamond-Back Rattlesnake, C. ada- 

 mantens, confined to the southeastern portion of the 

 United States, grows to a length of slightly over eight 

 feet, while it attains the greatest weight of any known 

 poisonous serpent. The bite of this terrible brute is 

 usually fatal, often within less than an hour's time. 

 The fangs are of greater length in proportion to the 



