Oc. Papers, Cau. Acap. Sc1., Vou. X [Van Denpurcu PuaTE 99 
Fic. 1. Crotalus molossus, Black-tailed Rattlesnake 
Section of skin of specimen collected at Cave Creek, Maricopa County, Arizona, April, 1910 
Fic. 2. Crotalus exsul, Red Diamond Rattlesnake 
Section of skin of specimen collected at Ensenada, Lower California, Mexico, February, 190s 
