MAMMALS OF THE MEXICAN BOtTKDABY. 27 



the Portrillo and Seca mountains had been occupied as residences. 

 In the Dog Mountains are small cliff houses, decorated with chal- 

 cedony and in an almost perfect state of preservation. On the banks 

 of the San Bernardino River, in the southeast corner of Arizona, 

 were discovered the large ruined buildings of pueblo pattern. A 

 "gigantic earthwork," in the shape of an ancient dam across the 

 Animas Valley, in the vicinity of Monument No. 67, is fully described 

 and illustrated by Lieutenant Gaillard in the American Anthropolo- 

 gist for September, 1896. 



Watersheds. — After leaving the Rio Grande the first divide, which 

 has gradually risen from sea level at the Gulf of Mexico to the alti- 

 tude of 1,130 meters, or 3,707 feet, at El Paso, is a low one between 

 the Rio Grande at El Paso and the Mimbres at liake Palomas, the 

 latter flowing south into old Mexico. The altitude of the Rio 

 Grande at the initial point of the Survey is, as just mentioned, 1,130 

 meters, and that of the Mimbres at the point where the Boundary 

 Line crosses it 1,210 meters, or 3,970 feet. 



The highest point on the line is the summit near the northern ex- 

 tremity of the San Luis Mountains, having an altitude of 2,048 

 meters, or 6,719 feet. From the Animas Valley or plain west of these 

 mountains the sudden break in the high plateau is decended through 

 Guadalupe Canyon, and we find ourselves in the valley of vhe San 

 Bernardino River, a northern tributary of the Yaqui, with an alti- 

 tude at the Boundary crossing (Monument No. 77) of only 1,133 

 meters, or 3,717 feet. Passing through a gap at the southeastern 

 extremity of the Mule Mountains, west of the San Bernardino River, 

 at an elevation of 1,430 meters, or 4,692 feet, the line crosses into (he 

 basin of the Gila River, which has an elevation of 1,298 meters, or 

 4,259 feet, at the crossing of the San Pedro River; 1,393 meters or 

 4,570 feet, at the first crossing of the Santa Cruz River (Monument 

 No. Ill) ; and 1,130 meters, or 3,707 feet, at the second crossing 

 (Monument No. 118). 



West of the Santa Cruz and of the city of Nogales the Pajaritos 

 Mountains are crossed. The initial Monument (No. 127) of the So- 

 nora azimuth section of the Boundary Line has an elevation of 1,592 

 meters, or 5,223 feet. The drainage from these mountains is toward 

 the Gila River on the north slope, and toward the Altar River on the 

 south. Monuments Nos. 137 to 140, near La Osa, practically mark the 

 dividing line between these basins, .^t this point the altitude is about 

 1,100 meters, or 3,609 feet, but rapidly diminishes to 300 meters, or 

 984 feet, on the Sonoyta Ri-ver at Quitobaquita to the westward. 



From Quitobaquita to the Colorado River lies a gradually sloping 

 stretch of desert sand, crossed by several ridges and two rocky desert 

 ranges of mountains that trend northwest and southeast. At the 

 Colorado River the altitude is 26 meters, or 85 feet. 



