TEIID LIZAEDS OF THE GENUS CNEMIDOPHORUS 193 



diameter. According- to Camp (191G, p. 530) "The tessellated 

 lizard, when running swiftly, elevates its tail so that the ground is 

 just cleared, and the tip lashes about as the lizard runs. Grinnell 

 and Storer (1924, p. 632) have pointed out that this lizard is 

 "specialized in somewhat the same manner as the kangaroo rat, 

 and to achieve the same result. Its whole organization is modified 

 for the attainment of speed in running on the surface of the 

 ground. * * * The legs are stout, especially the hind pair, and the 

 toes are long, particularly those of the hind feet. When frightened 

 one of these animals appears to get over the ground, for a short dis- 

 tance at least, faster than a man can run. Its usual procedure is to 

 start up suddenly, make a rapid dash of about 50 to 100 feet, then 

 stop abruptly, often dodging around behind a bush at the instant of 

 stoi^ping. The long tail serves as a counterpoise and perhaps also as 

 a rudder, in movement. The sudden start, extremely swift run, and 

 quick stop are, to the human eye, confusing, and may have the same 

 effect on any animal, such as the road-runner, which might attempt 

 to prey on the lizards. When undisturbed the whiptail forages 

 about with jerky movements of the body. The tail is then usually 

 dragged on the ground and leaves a characteristic trail between the 

 marks of the feet. When pursued one of these lizards will often take 

 shelter in some hole in the ground, usually at the base of a bush. 

 One was seen to enter a ground squirrel burrow." 



The burrowing habits of tessellatus are interesting and have been 

 rather fully recorded. The most complete account has been given 

 by Pack (1918, pp. 51-52), who described the process of burrowing 

 as follows: "The lizard began by scooping aside the sand with its 

 front feet. It used these feet alternatingiy, one stroke only being 

 made b3^ each foot at a time. Then, discontinuing the alternate 

 strokes, it would rest one foot while making a number of backward 

 strokes with the other. Soon it rested the employed foot and used 

 the other. After a short time it reverted to the way of digging 

 first described * * * When the burrow was well under way and 

 the excavated sand began piling up, the lizard turned around in 

 the depression, began slowly crawling outward, and instead of 

 scooping aside the sand, pushed it back with the face of the hands. 

 Then reentering the burrow, it resumed its digging, using the method 

 already described * ''' '' It continued burrowing until its move- 

 ments were again interfered with by the accumulating sand, which 

 it Avould once more push out. This process of digging was continued 

 until the burrow was finished. The lizard then, with its head facing- 

 outward, assumed a resting position at the end of the excavation." 

 Van Denburgh (1922, p. 519) Mrote that when hard pressed " It often 

 tries to elude pursuit by burrowing, although it can run very 



