The Rattlesnakes 



rattle nervously, shift its coils and inflate the body for combat. 

 On three occasions a companion of the same species was placed 

 in the cage, and this in each instance resulted in the original oc- 

 cupant refusing to feed. Upon the third trial it stubbornly 

 fasted for six weeks, when the offending serpent was removed. 

 The big rattlesnake took its rabbit two days after. 



THE MOUNTAIN DIAMOND RATTLESNAKE 

 (Mexican Phase of Crotalus atrox} 



On the Mexican Tableland, which extends into southern 

 Arizona, is a peculiar phase of Crotalus atrox that might be con- 

 fused with a more westerly species Crotalus oregonus owing 

 to the diamond markings (on most specimens) being rather blunt 

 and well separated not forming a connected chain. Such ex- 

 amples are yellowish or greenish, and the black and white bars 

 on the tail are dull and broken. These snakes appear quite 

 different from the powdery gray form, with the vividly marked 

 black and white tail, of the sub-arid plains and the deserts. The 

 head markings resemble Crotalus oregonus, owing to their defini- 

 tion and the breadth of the forward bar. Such specimens have 

 the forward portion of the head covered with irregular plates, 

 but no two examples show this character to be exactly alike. 



For this snake the technical name, Crotalus scutulatus, has 

 been proposed, but the many variations connect it with Crotalus 

 atrox. From the mountains near Tucson, Arizona, the writer 

 has received many specimens and in all degrees of variation; 

 while all of the examples are distinctly green, the pattern varies 

 from a chain of rhomb-like markings (on a few) to a series of well 

 separated, dark brown blotches. The average length is three 

 and a half feet. 



To Dr. Leonhard Stejneger, the writer is indebted for further 

 information concerning this rattlesnake. Following is part of 

 a letter from Dr. Stejneger, relating to some of the Tucson 

 specimens: 



'They are very interesting as they bear out my contention 

 that Crotalus scutulatus is not a definable form, but only repre- 

 sents a tendency in the Arizona-Sonoran specimens to revert to 

 the original condition, or else they represent the last vestiges of 

 this condition, it making but little difference, with regard to the 

 right of the form to have a name, which theory you adopt." 



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