THE SPIDER-MONKEYS. 247 



gion, and, to condense Mr. Wallace's account of it, it is of com- 

 paratively small extent; but the whole of its area is mountainous, 

 being, in fact, a continuation of the great range of the Rocky 

 Mountains. It varies in elevation above the sea from 6,000 to 

 18,000 feet. "With the exception of the elevated plateaus of 

 Mexico and Guatemala, and the extremity of the peninsula of 

 Yucatan, the whole of Central America is clothed with forests ; 

 and as its surface is much broken up into hill and valley, and 

 the volcanic soil of a large portion of it is very fertile, it is 

 altogether well adapted to support a varied fauna, as it does a 

 most luxuriant vegetation." In this region only species of 

 Spider-Monkeys (Ateles\ of Howlers (Alouatta), of Capuchins 

 (Cebus\ of Night-Monkeys (Nyctipithecus\ and of Squirrel- 

 Monkeys (Chtysothrix) are found. The Spider-Monkeys and 

 the Howlers alone extend so far North as Mexico, and the 

 Night-Monkeys reach to Nicaragua, while the Squirrel-Mon- 

 keys and Capuchins have penetrated no further than to Costa 

 Rica. 



The Brazilian Sub-region includes all the open plains and 

 pasture lands, surrounded by, or intimately associated with, the 

 forests. Its central mass consists of the great forest plain of 

 the Amazons, from the north-east coast of Brazil to high up in 

 the Andes on the west, a stretch of more than 2,000 miles ; 

 and from the mouth of the Onnoko to near La Paz in the 

 Bolivian Andes, a distance of 1,900 miles, of continuous forest 

 in both directions. Within this area are some open " campos " 

 or patches of pasture lands, along several of the tributaries of 

 the Amazon, and Llanos open flat plains generally flooded in 

 the wet season on the northern bank of the Orinoko. Un- 

 broken forest also covers the country from Panama south- 

 wards by the Magdalena Valley along the western aspect of the 



