190 BULLETIN 15 4, UNITED STATES NATIONAL MUSEUM 



food." They are particularly useful because they often enter alfalfa 

 fields, orchards and other cultivated areas. "The number of race- 

 runners in agricultural sections is now much fewer than formerly. 

 Great numbers have disappeared with reclamation of land, and un- 

 fortunately there has been an accompanying wanton destruction by 

 firearms. Where the race runner comes into contact with cultivated 

 lands it renders a service to agriculture" next to that of our most 

 useful insectivorous birds. " Thus, it becomes evident that this liz- 

 ard, in common possibly with the widespread eastern species (sex- 

 Ihieafm), is the most beneficial lizard in North America." 



An instance of true cannibalism was reported by Ruthven and 

 Gaige (1915, p. 26), who found that the stomach of a Nevada 

 example contained " a young, recently hatched, specimen of 

 Cnemiclojyhorus.'''' This young individual is considered to be tessel- 

 latus because other Cnemidophori are unknown from Nevada. 



Life history. — The life history of the tessellated lizard is very 

 imperfectly known, but the available data are sufficient to serve as 

 a substantial basis for further studies. 



There are apparently only two references to mating activity in 

 the literature. Taylor (1912, p. 334), working in Nevada, stated 

 that " Specimens were seen in copulation on June 10, and pairs 

 were commonly seen after this date. On June 21, one was found 

 pursuing another, but whether for purposes of play or by sexual 

 instinct is not known. Van Denburgh (1922, p. 519) merely said 

 that " It mates near Los Gatos (California) early in June." 



The eggs also have been but rarely studied. An account given 

 by McLain (1899Z>, p. 10) reads as follows: "Mr. Coolidge, while 

 in the Chihuahua Mountains, San Diego County, Calif., during the 

 summer of 1897, found four eggs of this form lying on top of the 

 small pile of earth which he says is always found at the entrance 

 to the burrows of these reptiles. They were lying in the open air 

 exposed to the full glare of the sun, where they had evidently been 

 left to incubate. The embryos were nearing the point of hatching, 

 as all external characters (excepting coloration) were fully devel- 

 oped and the yolk sac was j^retty well absorbed. The shell envelop- 

 ing the young is a tough membranous structure, oval in shape and 

 loss than an inch in length." While collecting in the panhandle of 

 Texas, Strecker (1910, p. 9) found two females with eggs, the num- 

 ber in each case being eight. He stated that these eggs resembled 

 those of gularis, but were a little larger. 



It is not definitely known when the eggs are deposited. However, 

 Ruthven and Gaige (1915, p. 26) wrote that " Females collected as 

 late as July 13 still carried their eggs, but those taken on August 

 8 had laid them. After a field expedition to northwestern Texas, 



