1883. ' 91 Trans. N. Y. Ac. Sci. 



form its eastern rim, has excavated a series of deep and rocky cafions, 

 which are impassable by boats and rival in their wild scenery those of 

 the Colorado of the West. The country, immediately bordering the 

 river, is much broken, but north and south there are intervals be- 

 tween the numerous and disconnected mountain-ranges, which are 

 grassy plains, presenting on a smaller scale the features of the Llano 

 Estacado on the north, and the Bolson de Mapimi on the south. 



Further west, we reach a still more broken and arid country, in New 

 Mexico, Arizona, Chihuahua and Sonora, where the ragged outlines 

 of the mountains, and the peculiar vegetation — mostly cactus — give a 

 special aspect to the scenery. This latter country, the home of the 

 Apaches, has been the theatre of active mining operations, for many 

 years, and the scene of unnumbered bloody tragedies. The country 

 lying within southwestern Texas, eastern Chihuahua and western 

 Coahuila, less rich in gold and silver, seems not to have proved suf- 

 ficiently attractive to the Mexicans to induce them to brave the danger 

 of its occupation, and it has been not only unoccupied, but much of it 

 unexplored. The line of the Mexican Central Railway, which is 

 being pushed southward from El Paso to the City of Mexico, passes 

 about 200 miles west of the belt of country referred to ; and the rail- 

 way which crosses the Rio Grande at Laredo, and is now extended 

 southwest to Monterey and Saltillo, is about as far away on the east. 

 A concession has been granted by the Mexican Government to Euro- 

 pean capitalists, to build a road from Presidio del Norte, or Eagle 

 Pass, or both, to Topolovampo, on the Gulf of California, and this 

 road will probably traverse, almost centrally, the district under con- 

 sideration. The general altitude of this country is from 4000 to 

 5000 feet, the Rio Grande, as it passes through it, falling from 3000 

 to 1000 feet above the sea level. 



BOTANY. 



The country bordering the Rio Grande, in Chihuahua and Texas, is 

 nearly destitute of trees, a feature which marks the aridity of the cli- 

 mate ; yet, in certain localities, as on the bottom lands of the Rio 

 Grande and Rio Concho, a vigorous and somewhat varied forest-growth 

 was found at the advent of the whites. No better illustration of the 

 relation between the kind of vegetation and the water supply in a 

 country can be found, than that afforded by the luxuriant growth of 

 trees of several kinds along the Cibola in the Chinati Mountains, Texas ; 

 while on all sides this oasis is surrounded by an apparently boundless, 

 grass-covered prairie, where the rain-fall is inadequate for trees. On the 

 mountain-summits, south of the Rio Grande, is a sparse growth of 

 pifion {Pinus eduh's), and evergreen oak, {Quercus Emoryi). The 



