93 
on a trip through the country to the westward toward the 
Gulf of California. The trip was made on horseback, our bed- 
ding and food being carried behind our saddles and camp 
was made in the open country. This gave me the opportunity 
of crossing a great mesa west of Torres transversed by a stream- 
way, which at that time of the year was entirely dry. At widely 
distant points, a few huts of Papago Indians were encountered, 
the inhabitants of which secured their water supply by digging to 
a depth of several feet in the streamway bed. This great sandy 
plain was partly covered with a forest of small acacia trees, 
Fic. 12. ‘*Cholla’’ or arborescent opuntia near Torres, Sonora. 
shrubby opuntias, and a Parkinsonia. The last named tree has 
finely subdivided switch-like branches and is known as “ Palo- 
verde,’ which formed the sole food for our horses during the 
entire trip. A very curious plant, known as ‘‘ Huarequi,’’ con- 
sisting of a large woody tubercle which rests on the surface of the 
ground under acacia trees, was seen for the first time. Durin 
the rainy season a rapidly growing vine is sent up which bears 
a profusion of white flowers, then the plant goes into inac- 
