520 University of California Publications in Zoology [Vol. 12 



men from Blythe Junction (no. 5472), the total length is 194 mm., 

 tail length 111 mm. A specimen from Barstow, San Bernardino 

 County (no. 5385), is 223 mm. in total length, and 130 mm. in length 

 of tail. 



This lizard is abundant on the open desert around the Turtle 

 Mountains. It does not occur on the rocky hillsides, and even in the 

 sandy canon bottoms is found but sparingly. It is on the open 

 stretches of desert dotted with creosote bushes that this species is 

 typically at home ; and here it outnumbers all the other diurnal verte- 

 brates combined. Individuals may be observed bobbing up and down, 

 switching the tail from side to side, walking jerkily along with the 

 tail curled over the back, or running with such speed that the eye can 

 barely follow. The writer estimated that one of these swift lizards 

 covered a distance of 90 feet in four seconds, which would be travel- 

 ling at a rate of about fifteen miles an hour. The lizards can stop and 

 start with the most confusing abruptness, and rarely run straight 

 away but describe a circle when pursued. When tired out they may 

 crouch close to the ground and will then permit themselves to be 

 caught ; or they may burrow into loose sand by wriggling the head 

 from side to side and pushing with the hind feet while the front feet 

 remain pressed close to the side. Sometimes when closely pursued 

 they enter holes. 



Of eight stomachs examined not one contained plant remains, the 

 contents being insects, small pebbles, part of a shed lizard skin, and 

 parasitic nematode worms. Perhaps, like some of the geckos, these 

 lizards eat their own shed integument. The insects represented in- 

 cluded eight Orthoptera, eight ants, and several small Coleoptera. 

 Some of the grasshoppers and crickets were of large size (40 mm. long) 

 and had been swallowed entire. These lizards sometimes spring a foot 

 or more to seize a tempting bait; and I saw one, probably by mistake, 

 leap over the edge of an eight-foot wash-bank while jumping for a 

 grasshopper in a bush. At Blythe Junction a gridiron-tailed lizard 

 was seen regularly at a certain doorstep picking up dead crane-flies 

 and other night-flying insects thrown there by the housewife. The 

 lizard apparently became so absorbed in picking up, shaking and 

 swallowing the gauzy-winged flies that it many times permitted the 

 observers to touch it lightly upon the back. 



After sundown the gridiron-tail buries itself in sand, and when 

 alarmed as by an approaching team or pedestrian will start up sud- 

 denlv and dash away. 



