47. SISTRURUS 



of small chestnut-brown blotches along the sides and a row 

 of large brown dorsal blotches. A pair of elongate brown 

 blotches extend from the supraoculars back onto the neck. 

 A narrow chestnut-brown band extends down and back from 

 the prefrontal plate to the eye and on to the neck, and is 

 bordered below by a narrow yellowish stripe which extends 

 from the nostril to the angle of the mouth. The snout and 

 upper jaw are brown, with two yellow rays diverging from 

 the pit. The chin and lower jaw are mottled with brown 

 and yellow. The dorsal blotches are about 34 to 45 in num- 

 ber between the head and the anus, and are somewhat irreg- 

 ular in shape. They are brown bordered with black and 

 margined with yellow. There are about four to eight simi- 

 lar blotches on the tail. The lateral blotches are proportion- 

 ally small, and alternate with the dorsal and the other lateral 

 series. Those of the upper series are more or less obsolete. 

 Those of the second series are darker and occupy scales of the 

 second, third and fourth rows. The lowest series is con- 

 fined to single scales of the first and second rows. The 

 belly is light straw-color, irregularly dotted and sprinkled 

 with brown. 



Length to anus 187 248 380 412 450 



Length of tail 28 32 53 63 70 



Distribution. — Edwards Massasauga ranges from Okla- 

 homa through western Texas to the Mexican border. Three 

 specimens have been found in southeastern Arizona. Two 

 of these, collected by H. W. Henshaw, have no more defi- 

 nite locality. The third specimen was secured, by Dr. Wil- 

 cox, on the parade ground of Fort Huachuca, Cochise 

 County. 



