192 BULLETIN 15 4, UNITED STATES NATIONAL MUSEUM 



From observations in the Texas panhandle Strecker (1910, p. 9) 

 rehites that " they were most active early in the morning', when they 

 were out feeding along the edges of cow paths and around the bases 

 of cedars growing along the canyon side. Several adults observed 

 late in the evening were lying along the beveled edges of large 

 masses of stone with their heads extending above the rim in order 

 to get the full benefit of the declining rays of the sun." 



In Texas, New Mexico, and Arizona the writer has found that 

 these lizards ordinarily became active soon after sunrise and con- 

 tinue their activity well into the morning (July). Thus, a young- 

 desert whiptail observed at Hazen, Churchill County, Nev., at 7.30 

 a. m. on August 25, 1928, had taken a position on the eastern side 

 of a desert bush, its head directed toward the morning sun. Here 

 it remained perfectly still, api^arently enjoying the warm rays. In 

 the afternoon fewer specimens seem to be about and it is probable 

 that after satisfying their hunger individuals retreat to some under- 

 ground shelter for rest and digestion, coming out again only when 

 disturbed or hungry. 



Many remarks have appeared concerning the speed, flight, and 

 concealment of the race runners and Avhiptails. In regard to 

 tessellatus^ Stejneger (1893, p. 199) seems to have been the first to 

 state that " It runs wdth great rapidity when alarmed." Ruthven 

 (1907, p. 563), working in the vicinity of Alamogordo, New Mex., 

 noted that "When frightened, specimens did not seek concealment 

 in the nearest bush, but dashed away swiftly for several rods before 

 stopping. They generally stopped near a bush and after looking 

 about for a moment slipped quietly into it, frequently leaving it 

 directly again on the other side for a neighboring one. The tendency 

 to repeat this process makes these lizards very difficult to capture." 

 It was found by the present writer that when two collectors are 

 working together they may turn the tendency of tesselJatus to slip 

 directly through a bush to advantage. When a lizard is seen or 

 heard in a bush it may be " scared " to almost any side of the area 

 by the approach of a person from the opposite quarter. If the second 

 collector remains motionless on the side of the bush at which the 

 whiptail is expected to appear, the animal, apparently unaware of 

 the presence of danger, will usually come into full view. 



A somewhat different behavior was reported at Cabezon, Calif., 

 by Atsatt (1913, p. 40), Avho noted that they " ran along the ground 

 and burroAved in the soft sand or crawled under cactus. At Snow 

 Creek they took refuge between or under rocks without running 

 along the ground for a great distance." A case similar to the lat- 

 ter was observed by the Avriter in Reeves County, Tex., where a 

 specimen was seen taking shelter under a flat stone about a foot in 



