116 BULLETIN 56, UNITED STATES NATIONAL MUSEUM. 



(411 miles) west of the Rio Grande and 198 kilometers (123 miles) 

 east of the Colorado River. Altitude, 400 meters (1,312 feet). The 

 Mexican town of Sonoyta, beside which our camp was located, is 

 near the head of the Sonoyta River, a pretty creek containing several 

 species of fish, which rises south of Monument No. 164 and flows 

 west to Quitobaquita, where it almost touches the International 

 Boundary Line, and thence southwest to the Gulf of California. 

 Some months prior to our arrival, during a period of unusual rain- 

 fall the river had washed away its banks in such a manner as to 

 destroy the then existing system of irrigation entirely and to prevent 

 its reconstruction. At the time of our visit only a few fields on the 

 right (north) side of the Sonoyta River were under irrigation, and 

 these received their water from springs at some distance from the 

 river. Trapping would have yielded better results for our mammal 

 collection had we been there during the period of agricultural pros- 

 perity. 



Below the village of Sonoyta is a settlement of Papago Indians, 

 who successfully irrigate large^fields from the Sonoyta River. The 

 ground had been well plowed with the ingenious wooden plows made 

 by the Indians. 



A few miles farther down the stream is the Mexican town of Santo 

 Domingo, distant about 14.5 kilometers. (9 miles) from Sonoyta. 

 The freshet, which had been calamitous to the people of Sonoyta, 

 had greatly benefited the residents of Santo Domingo by turning all 

 of the water of the Sonoyta River into their irrigation canal. 



These settlements of the Sonoyta Valley are surrounded by low 

 mountains and hills — the Sierra de Sonoyta. The highest peaks 

 (altitude, 1,348 meters, or 4,423 feet) are about 15 kilometers (9 

 miles) south of the Boundary, while those to the north of it, in the 

 vicinity of our station, are from 600 to 900 meters (1,000 to 1,450 

 feet) in altitude. They are covered with a growth of shrubbery and 

 cactus, so that open, grassy stretches of country are no longer visible 

 to the eye, when viewing the country from an elevation, as they are 

 in the region east of the Baboquivari Mountains. The bushy or 

 chaparral country begins about 16 kilometers (10 miles) east of Pozo 

 de Luis (Station No. 52 south of Monument No. 152) and extends 

 west to La Represo (Monument No. 179). From the latter point to 

 the Coast Range of mountains, near the Pacific coast, lies the most 

 barren desert of America. 



Desert vegetation is abundant around Sonoyta. Fig trees thrive 

 in a half-wild state, cottonwoods and willows border the fields and 

 acequias, and a luxuriant thicket of young mesquite edges the So- 

 noyta, where it has not been dug away to make place for fields and 

 gardens. On the hills the giant cereus and pitaya are the most 

 marked features of the arboreal vegetation, the latter preferring the 



