956 16. CROTALIDE 
three miles south from Lovic, Oro Grande, and Needles, 
San Bernardino County; Indio, Torres, Mecca, and Blythe 
Junction, Riverside County; and on Echo Island in the 
Salton Sea, at New River near the Salton Sea, Holtville, 
Coyote Wells, Laguna Station, and Pilot Knob, Imperial 
County, and in La Puerta Valley, San Diego County. 
Habits.—In certain parts of its range, as in the Colorado 
and Mohave deserts, this species is very numerous, but owing 
to its coloring and habits individuals seldom are seen. The 
name “side-winder” is derived from its peculiar mode of 
progression: “when disturbed it moves away sideways, keep- 
ing its broadside toward the observer instead of proceeding 
in the usual serpentine manner. * * * One was shot con- 
taining a kangaroo rat (Dipodomys) and two pocket mice 
(Perognathus). * * * During the latter part of April and 
the early part of May these rattlesnakes were often found 
in pairs and were doubtless mating. At such times they re- 
mained out in plain sight over night instead of retreating to 
holes or shelter under desert brush, and on two occasions they 
were found by us on cold mornings so early that they 
were too chilled to move until considerably disturbed.”* 
Heller is quoted by Meek as stating that it is strictly 
nocturnal. I have found it to be not entirely inactive in the 
daytime. Two were found coiled in the mouths of rodent 
holes in clumps of cactus where they were lying in the sun. 
One was found crawling under a bush, and one hidden under 
a tin can. One was found out on the desert at night, and 
it is probable that most rattlesnakes are most active at that 
time. Camp states that both at Needles and near Blythe 
Junction individuals were traced by the characteristic tracks 
in the sand. Each was found closely coiled in a symmetrical 
pad and partly buried fiush with the surface in the hot sand 
“Merriam, N. Amer. Fauna No. 7, 1893, p. 217. 
