Mat, 1893.] REPTILES OF THE DEATH VALLEY EXPEDITION. 171 



are constant aud that the two forms d o not intergrade. That Boulenger 

 (Cat. Liz. Br. Mus., II. 1885, p. 206) failed to appreciate the difference 

 is probably due to the fact that he had only two specimens of one 

 species, probably G. ventralis, before him. 



As to the geographical distribution of the two species it may be stated 

 that G. draconoides is restricted to the very southern extremity of the 

 Lower California peninsula — that is, to the zoo- geographical district 

 which has been termed the Cape Begion, or Cape St. Lucas Region. 



While this species, therefore, is of a very limited range, G. ventralis 

 ranges over a comparatively large area, comprising, so far as known, 

 the northern portion of Lower California; the coast of Sonora, Mexico, 

 at least as far south as Guayinas; the desert regions of southern Cali- 

 fornia; southern Arizona as far east as Camp Apache and Fort Buch- 

 anan, at least; southern and western Nevada as far north as Pyramid 

 Lake; southern Utah, where it is restricted to the Lower Santa Clara 

 Valley. * 



It can be asserted with confidence that Gallisaurus ventralis does not 

 occur anywhere within the interior valley of California, not even in 

 Walker Basin. Nor is there any evidence to show that it occurs any- 

 where southwest of the San Bernardino range, within the boundary of 

 the State of California. 



[The gridiron-tailed lizard is the most characteristic reptile of the 

 Lower Sonoran deserts of southern California, southern Nevada, south- 

 western Utah, and Arizona, where it is almost universally distributed 

 and very much more abundant than any other species. It inhabits the 

 open deserts and runs with great swiftness over the sand and gravel 

 beds, carrying its tail curled up over its back as if afraid to let it touch 

 the hot surface of the earth. It starts off at full speed, as if fired from 

 a cannon, and stops with equal suddenness, thus escaping or eluding its 

 enemies, the coyotes, hawks, and larger lizards. When running it 

 moves so swiftly that the eye has difficulty in following, and when at 

 rest its colors harmonize so well with those of the desert that it can 

 hardly be seen. The basal half of its tail is transversely barred under- 

 neath, and the bars are broad and distant, suggesting the name here 

 applied to the species in lieu of a better one. During the breeding 

 season the males develop a conspicuous patch of metallic greenish-blue 

 on the sides of the body and have the power of inflating a pinkish sac 

 under the chin. 



The attitude of this lizard when at rest differs from that of most 

 others in that the knees and elbows stand out at right angles from the 

 body and are elevated to such a degree that they nearly reach the 

 plane of the back. Like many other species, it has an odd habit of per- 



* Some authors even include Texas in the geographical distribution of this species 

 (and genus), hut with no foundation in facts. I am not aware of an authentic record 

 of its having been collected in New Mexico. The type came from what was then ' New 

 Mexico/ hut in those days that included Arizona as well. 



