one a Bur sera with papery buff colored exfoliating bark, the other a 

 tree of very similar appearance but leafless in the winter season and 

 suggestive of Jatropha. 



It was among these desert hills west of Torres that we had an 

 opportunity to see a Papago Indian extract from a bisnaga (^Echino- 

 cactus emoryi)^ or barrel cactus, water with which to quench his 

 thirst. He cut the top from a plant about five feet high and with a 

 blunt stake of palo verde pounded to a pulp the upper six or eight 

 inches of white flesh in the standing trunk. From this, handful by 

 handful, he squeezed the water into the bowl he had made in the top 

 of the trunk, throwing the discarded pulp on the ground. By this 

 process he secured two or three quarts of clear water, slightly salty and 

 slightly bitter to the taste but of far better quality than some of the 

 water a desert traveler is occasionally compelled to use. The Papago 

 dipping this water up in his hands drank it with evident pleasure, and 

 said that his people were accustomed not only to secure their drinking 

 water in this way in times of extreme drouth but that they used it also 

 to mix their meal preparatory to cooking it into bread (Plate XVIII). 



About eight miles west of Torres Yaki settlements begin (Plates 

 XIX and XX). One abandoned house had a ridgepole made of a 

 palm trunk. This was notched in the manner followed by the aborigines 

 in pre-Columbian times in making a ladder, and it is evident that it had 

 been put to such a use before it was employed as a ridgepole. This 

 palm trunk, it is believed, must have been brought from the mountains 

 westward toward the Gulf of California, and very likely it indicates the 

 occurrence there of groves of Neowashingtonia. This together with 

 the presence of Guaiacum and Haematoxylon shows why this part of 

 the Sonoran desert is treated by some American students as belonging 

 to the tropics, although the desert character of the region is not at all 

 suggestive of the vegetation we are inclined to regard as representing a 

 tropical environment. 



GUAYMAS. 



The flora in the harbor of Guaymas is a desert flora similar to that 

 at Torres but apparently subjected to severer conditions of aridity. 

 The creosote bush (^Covillea tridentata)^ the plant most widely dis- 

 tributed in the more severely dry deserts of the southwestern United 

 States, appears here again after a long intermission across the plains of 

 northern and middle Sonora. Many of the trees and shrubs are of the 

 same species as those in the vicinity of Torres, but of smaller growth. 

 The hecho ( Cereus pecten-abortg-inum') , whose bur-like fruits are often 

 used for hair brushes by the Indians, had appeared along the railroad 



