94 
tivity for the remainder of the year. Numbers of large speci- 
mens of Cereus ingens (?) were seen. 
The shrubby opuntias (‘‘Chollas’’) in many places covered 
the entire open space among the small trees, offering extremely 
difficult and dangerous passage for horses. The segments of the 
branches bear spines from one to three inches in length, and are 
very easily detachable. The slightest contact will drive the spines 
into the flesh, and the branch breaking off from the plant, be- 
comes extremely difficult to remove. 
During one day of this trip we crossed the trails of small 
parties of Yaqui Indians, and were compelled to keep the saddle 
Fic. 13. Outfit and crew for ee large cacti in front of a clump of 
‘organ’? cactus, or Cereus Thurber 
almost all the time and to ride far into the night to lessen the 
chance of an encounter with them. Our scant water supply was 
supplemented by using the juices of the fleshy fruits of some’ of 
the opuntias. Along the lower foothills at the edge of the mesas, 
great numbers of small trees with white bark were seen, which 
bore the name of “ Palo blanco”’ being a tree morning-glory 
(fpomva arborescens). Although entirely destitute of leaves at 
this time of the year, a few characteristic white flowers were 
seen, The tips of the branches of this tree furnish an agreeable 
forage to deer, which we saw in great numbers. 
