526 CALIFORNIA ACADEMY OF SCIENCES. 



this very interesting species has been considered one of 

 the rarest of our reptiles. 



Distribution. — In reality, X. vigilis is the most abun- 

 dant lizard in the territory it has chosen for its home. It 

 seems to be peculiarly dependent upon the presence of 

 tree yuccas. A glance at Dr. Merriams' map* shows 

 that these weird plants grow in each of the localities from 

 which the species has been recorded, viz. : Fort Tejon in 

 the Canada de las Uvas, and Hesperia, in California, and 

 Pahrump Valley, in Nevada. 



Dr. Charles H. Gilbert and the writer collected speci- 

 mens near Mojave, and found a portion of a cast skin at 

 Victor, California, in November, 1893. In September of 

 the following year, the writer found this species common 

 at Mojave and Hesperia, and secured a single specimen 

 near Cabazon on the eastern slope of San Gorgonio Pass, 

 California. The first three of these localities are situated 

 in the great Yucca arborcscens belt, which extends along 

 the southwestern edge of the Mojave desert. The last 

 is in a small and apparently isolated grove of smaller tree 

 yuccas, seemingly of another species. 



Habits. — Mojave, California, Nov. 4, 1893. About a 

 mile from the station, there is a considerable forest of 

 Yucca arborcscens. The many trees and wind-broken 

 branches, which lie decaying on the ground, afford a 

 home to numerous colonies of white ants, scorpions, vis- 

 cious-looking black spiders, and several species of beetles. 

 In a deep crack of one of these branches a small lizard 

 was discovered which, when caught, proved to be a young 

 Xantiisia vigilis. Probably it had not yet learned how to 

 hide from the day, for I have never seen another undis- 

 turbed individual. 



The key to their home once discovered, the collection 



*N. A. Fauua, No. 7, Map 5, 1893. 



