Carriker : List of the Birds of Costa Rica. 317 



The high peaks, rising above the regions of the central plateau, 

 constitute quite a distinct life-zone, reaching as they do to an altitude 

 of from eight to eleven thousand feet. The principal peaks are the 

 volcanoes, Poas, Barba, Irazu, and Turrialba, grouped together in the 

 central portion of the country, and Pico Blanco and Rovalo in the 

 southeastern part, while between these are many unnamed ranges, the 

 summits of which attain an altitude of from seven to eight thousand 

 feet. 



The main continental range extends from the extreme northwestern 

 corner, where it is low, to the east central portion, increasing in height 

 and ending in a chain of volcanoes, the last of which is Turrialba. 

 Here there is a break formed by two deep, broad valleys, the Reven- 

 tazon from the Caribbean and the Rio Grande de Tarcoles from the 

 Pacific, the sources of which are within a half mile of each other at 

 the narrow divide known as "El Alto," which has an elevation of 

 but five thousand feet. 



Practically the whole of the country to the southeast of these valleys 

 is an unbroken expanse of mountain, valley, river, and jungle, with few 

 inhabitants, except the nondescript and rapidly diminishing Indians. 

 There are no reliable maps of the region and but little is known con- 

 cerning the avifauna outside of the Sicsola Valley on the Caribbean 

 and the Terraba Valley on the Pacific slope. 



On the western side are several more or less isolated groups of moun- 

 tains, ranging in altitude from four to eight thousand feet, the prin- 

 cipal being the Cerro de Santa Maria (2,000 to 4,000 feet) in the 

 upper part of Guanacaste ; the Aguacate Mountains, lying just back 

 of Puntarenas (2,000 to 5,000 feet) ; the Dota Mountains, farther to the 

 south (2,000 to 8,000 feet) ; another (unnamed) lying between the 

 Rio Grande de Terraba and the Pacific coast and lastly a small range 

 in the Peninsula de Osa, outside the Golfo Dulce. 



The principal rivers of the Caribbean slope are the Zapote, Frio, 

 San Carlos, Sarapiqui, Sucio, and Toro Amarillo, emptying directly 

 or indirectly into Lake Nicaragua or the San Juan River, while the 

 Reventazon, Pacuare, Matina, Banana, Estrella, and Sicsola empty 

 into the Caribbean. On the Pacific slope the streams are fewer, but 

 larger. North of the Gulf of Nicoya there is but one of any impor- 

 tance, the Tempisque, which drains the whole of the northwestern 

 portion of the country and empties into the head of the Gulf of 

 Nicoya. The Barranca and Grande de Tarcoles empty into the eastern 



