From the southern frontier of the United States it stretches down to the isthmus which connects the northern and southern mainlands of the great American continent. On the west its shores are washed by the waters of the Pacific; on the east, by those of the Mexican Gulf and Caribbean Sea. Roughly speaking, its area is about 850,000 square miles; its population may number ten souls to a square mile. Its form of government is pseudo-republican; and for administrative purposes it is divided into twenty-five provinces. Its capital, Mexico, has 200,000 inhabitants: its only other important towns are Puebla, 75,000 inhabitants; Guadalajara, 65,000; Guanajuata, 50,000; and San Luis and Merida, about 45,000 each. A glance at the map will show you that Mexico consists in the main of an elevated table-land, which in the south rises up into the Cordilleras of Central America, and on the east and west descends, by more or less gradual terraces, to the sea-coast. Owing to its geographical position, this table-land enjoys the profuseness and beauty of a tropical vegetation; on the other hand, its climate is so tempered by its various elevations, which lie between 5000 and 9000 feet, that it has been found possible to naturalize the European fauna and flora. A remarkable geological feature is the volcanic belt or chain that runs from ocean to ocean between the parallels of 18° 15′ and 19° 30′ north latitude, and is marked by several active as well as extinct volcanoes. Among them may be named Orizaba, Cittalapetl (“The Mountain of the Star”), Popocatapetl (“The Smoking Mountain”), 17,884 feet, Istaccihuatl (“The White Woman”), and Toluca. Most of the mountain chains that break up the table-land are of comparatively low altitude; the principal is the Sierra Madre, or Tepe Serene. The two chief streams are the Rio Santiago and the Rio Grande del Norte.