M\MMM.S OF THE MEXICAN BOUNDAET. 



101 



Station No. 34. — San Pedro River at Monument No. 98, 395 kilo- 

 meters (245 miles) west of the Rio Grande. Altitude L,298 meters 

 (4,259 feet). The San Pedro River ;it this point is a good-sized 

 stream, containing many fish, batrachians, and turtles, and its 

 waters and banks are inhabited by numerous aquatic species of mam- 

 mals and birds. There arc however, no meadow- or marshes of any 

 considerable extent along its banks in this part of its course. Trees 

 are limited to the edge of the stream, where willow, ash, boxelder, 

 cottonwood. and mesquite are the common species. (Plate X. fig. 

 2.) The adjacent Iluaehuea Mountains, of Arizona, crossed at their 

 southern extremity by the International Boundary Line some 13 

 kilometers (8 miles) to the westward, are well wooded to the base. 

 I was at this station from October 10 to November 1, 1892; July 27 

 to August 2, and October 10, 1893. Mr. Holzner, from October 10 

 to November 2, 1892. Important collections were made. 



Flora of San Pedro Valley. — The collections of plants made near 

 Monument No. 98 includes the varieties indicated in the lists below. 



The trees are : 



Juglans rupestris Engelmann. 



Salix nigra Marshall. 



Salix occiiJrutiilis loni/ipc* (Anders- 

 son) Bebb. 



Salix taxifolia Humboldt, Bonpland, 

 and Kunth. 



Populus fremontii Watson. 



Celtis reticulata Torrey. 



Mont* celtidifolia Humboldt, Bon- 

 pland. and Kunth. 



Platanus wrightii Watson. 



Acacia greggii Gray. 



Acacia constricta Bentham. 



Prosopis glandulosa Torrey. 



Acer negundo Linnaeus. 



Sapindus marginatus Willdenow. 



Fraxinus velutina Torrey. 



Chilopsis linearis- (Cavanilles) Sweet. 



Other conspicuous vegetation includes: 



Yucca glauca Nuttall. 

 Atriplex sp. 

 Rhus glabra Linnaeus. 

 Mimosa dysocarpa Bentham. 

 Acacia pMculoides (Cavanilles) Tre- 

 lease. 



Covillea tridentata (de Candolle) Vail. 

 Opuntia I several species I. 

 Cucurbita fcetidissima Humboldt, Bon- 

 pland. and Kunth. 

 Apodanthera undulata Gray. 

 Perezia sp. 



Station No. 35. — Huachuca Mountains. Arizona. This isolated 

 but extensive range (called Sierra Espuela by the early explorers) 

 rises from a base level of 1,275 meters (4,183 feet) to the height of 

 2,887 meters (9,472 feet). It is almost wholly within the United 

 States, extending nearly north from Monument No. L02 for a dis- 

 tance of 32 kilometers (20 miles). It is 407 kilometers (253 miles) 

 we-t of the Rio Grande. The highest point. Hasslops Peak, is II! 

 kilometers (9 miles) north of the Mexican line. The higher timber 

 line is not reached by any of the mountains visible from the Mexican 

 Boundary Line. In the Huachuca range the lower timber line de- 



