The Rattlesnakes 



Following are the measurements of a young specimen cap- 

 tured in Mexico, a short distance over the border and south of 

 Arizona: although these measurements are below that of the 

 adult, they show the general proportions: 



Total Length 20 inches. 



Length of Tail, not including rattle i 



Greatest Diameter f " 



Width of Head if " 



Length of Head i J 



The specimen had a perfect rattle of five segments and, 

 judging from the size of the basal ring, was about two-thirds 

 grown. 



Distribution. — In the United States the range of this species 

 extends but a slight distance north of the Mexican boundary — 

 not beyond the central portion of Arizona and as far north as 

 this it is rare. 



North of the Mexican boundary it occurs from the Pecos 

 River in Texas to slightly more than the central portion of Ari- 

 zona. The most northerly record of capture in New Mexico 

 appears to be Fort Bayard. Two specimens were captured 

 by Dr. E. Coues on San Francisco Mountain, in Arizona.* 



In New Mexico and Arizona, immediately adjacent to the 

 Mexican border the species seems to be common. The writer 

 has received several skins from Tucson, Arizona. Following 

 is a paragraph from a letter from Mr. Herbert Brown, of Yuma, 

 Arizona: "The Black-tailed rattlesnake is fairly common in 

 the Santa Catalina and Rincon Mountains, near Tucson." 



The range of this snake into Mexico is not definitely known. 



Habits. — Like many of the rattlesnakes this species fre- 

 quents rocky places, lurking in the vicinity of the mountain 

 ledges where the numerous fissures afford it shelter. 



THE BANDED OR TIMBER RATTLESNAKE 



Crotalus horridus, (Linn.) 



In its pattern and colours this Eastern species exhibits great 



variation. It is the only rattlesnake occurring over the greater 



portion of its range, but in the South and West its distribution 



overlaps the range of several species; they are so distinct as not 



* Stejneger, Report of U. S. National Museum, 1893, p. 426. 



441 



