THE MEXICAN EIVERS. 41 



Being skirted by loftier ranges running nearer to the sea, the Pacific side of 

 Mexico presents far less extensive low-lying coastlands and secondary beaches than 

 the Atlantic side. Nevertheless, even here there are a few coast lagoons, especi- 

 ally in the district west of Acapulco. Beyond it the sea receives the waters of 

 the E,io Mexcala or de las Balsas, one of the chief Mexican rivers, whose farthest 

 sources lie on the southern and some even on the eastern sIojdcs of the volcanic 

 range. The Apoyac, its principal headstream, which flows by Puebla, rises on the 

 flanks of Ixtaccihuatl and is fed higher up by the snows melted by the thermal 

 springs, lower down by several saline rivulets. 



The Rio de las Balsas, that is, " of the rafts," as indicated by its name, is, to a 

 limited extent, navigable along its lower reaches ; above the bar it is accessible to 

 small craft, which, higher up, are arrested by rapids, whirlpools, and a high cas- 

 cade. For a space of 220 miles there occur no less than 226 obstacles of this sort, 

 eddies, rapids, or dangerous reefs. The volume discharged through the two 

 mouths of the Mexcala is estimated at 2,500 cubic feet per second. The E,io Tux- 

 pam, or de Colima, and the Amecas, two less copious streams which reach the 

 Pacific farther north, have a mean discharge of 1,100 and 750 cubic feet respectively. 



The Rio Lerma, or Santiago, the Tololotlan of the Indians, is also a considerable 

 stream. By the riverain populations it is, in fact, known as the " Rio Grande," 

 while the inhabitants of Michoacan call it also Cuitzeo, from the large lake situated 

 in their province. It rises in the State of Mexico in the very centre of the Ana- 

 huac plateau, and its farthest sources, issuing from underground galleries, descend 

 from the Nevado de Toluca down to the twin lake of Lerma, the remains of an in- 

 land sea which formerly filled the upper Toluca valley north of the Nevado volcano. 



At its issue from the lake, or rather marshy lagoon, the Lerma stands at the 

 great altitude of 8,600 feet, and during its winding north-westerly course across 

 the plateau, the incline is very slight. In this upland region it is swollen by 

 several afiluents, some of which, like the main stream itself, flow from lakes dotted 

 over the tableland. After completing half of its course at La Barca, the Lerma is 

 still over 5,600 feet above sea-level. Here, some 280 miles from its source, it enters 

 the large lake Chapala, near its eastern extremit}^ ; but about 12 miles below the 

 entrance it again emerges through a fissure on the north side of the lake, and still 

 continues to flow throughout its lower course in the same north-westerly direction. 



Chapala, thus obliquely traversed by the current of the Lerma, is the largest 

 lacustrine basin in Mexican territory ; but this flooded depression, about 600 

 square miles in extent, is very shallow, its mean depth being only 40 feet, and 

 the deepest cavities not more than 110 feet. Evei-y where, but especially on the 

 north and east sides, its blue limpid waters are encircled by an amphitheatre of 

 hills, whose slopes are covered with a rich growth of forest trees and lianas. The 

 shores of this romantic basin present some of the loveliest scenery in Mexico ; but 

 till recently few travellers ventured to visit these almost uninhabited regions. 



At present a railway runs along the north-east side of the lake, and it has even 

 been proposed to found a school of navigation on one of the inlets of the inland sea. 

 Other lakelets dotted over the slopes of the mountains about the western extremity 



