MAMMALS OF THE MEXICAN BOUNDARY. 115 



of the pitaya cactus {Gereiis thurheri)^ wliich to the westward 

 become a conspicuous feature. Large game was abundant in these 

 mountains. General collections of unusual interest were made here 

 by Mr. Holzner and the author from December 29, 1893, to Januar}' 

 8, 1894. The winter season was unfavorable for collecting reptiles, 

 Uta stanshurkina being, as usual, the only lizard common at that time 

 of the year. 



Flora of Pozo de Luis. — The trees are : 



Salix nigra Marshall. 

 Populus frcmontii Watsou. 

 Acacia grcggil Gray. 

 Prosopis glandulosa Torrey. 

 Parkinsonia microphylla Torrey. 

 Cercicliinn torrcijanion (Watson) Sar- ! Cercus giganteus Engeliiianii. 

 gent. I Cereus tliurheri Engehnann. 



Olneya tcsota Gray. 

 Opuntia fulgida Eugelniann. 

 Opuntia versicolor p]ngelniaiHi. 

 Opuntia spinosior (Engehnann) Tou- 

 rney. 



Other conspicuous plants are of the genera Ephedra., Y^icca., Dasy- 

 Urion, A(/a/:e, Amaranthus, AtHplex, Fouqideria, CoviUea, Simiriond- 

 sia, Ehus, Zizyphns, Cactus, Echinocereus, Eehinocartus, Opuntia, 

 DatiiTG, Bo}ira7'dia, G ucurhita, Xanthium, and Baccharis (several 

 species, including B. emoryi). 



Station Xo. 53. — Xariz Temporal, Sonora, ]Slexico. Station about 

 10.5 kilometers (6.5 miles) south of Monument Xo. 159, 626 kilo- 

 meters (389 miles) west of the Rio Grande, and 233 kilometers (145 

 miles) east of the Colorado River. Altitude, 500 meters (1,640 feet). 

 Our camp was at the south end of the Xariz Mountains, beside a pool 

 of surface water, at the western border of the Great Plain, which 

 stretches between the Cobota and Xariz mountains. Much of the 

 Great Plain, which is from 100 to 200 feet lower on the west than on 

 the east side, is covered with grass, though shrubs and cacti cover 

 large portions of it. The Xariz Mountains are very rocky, but sup- 

 port considerable undergrowth, especially near the base, which is also 

 wooded with pitaya cactus, Sonoran ironwood {Olneya tesota). 

 palo verde, and acacia. Along the laguna at the foot of the Xariz 

 Mountains is a heavy growth of mesquite, about 15 feet in height. 

 A very superficial examination of this interesting locality was made 

 by Mr. Holzner and myself on January 8 and 9, 1894, when a few 

 specimens were collected. Major Emory had taken the horned toad 

 {Anota modesta Girard) at this place. 



Station Xo. 54. — Santa Rosa Valley, at Monument Xo. 161, 632 

 kilometers (393 miles) west of the Rio Grande, and 343 kilometers 

 (141 miles) east of the Colorado River. Altitude, 516 meters (1,693 

 feet). Visited by myself and Mr. Holzner January 9, 1894. 



Station Xo. 55. — Sonoyta, Sonora, Mexico. The camp was at 

 the edge of a mesquite flat beside the Sonoj'ta River, about 3 kilo- 

 meters (2 miles) south of Monument Xo. 168, which is 661 kilometers 



