386 ANNUAL EEPOET SMITHSONIAN INSTITUTION, 1908. 



Accompanying this pajDer will be found a bibliography of the 

 more important literature, and in the footnotes some additional refer- 

 ences are given. Nearly all of the literature of the subject has been 

 consulted in the preparation of this review, but it has not been deemed 

 advisable to publish a more complete bibliography, since some of the 

 articles with elaborate titles have in reality little value and, being 

 quite inaccessible to the general student, can hardly hope to hold a 

 place with the more important contributions, which embody the 

 essential truths with fewer errprs. 



Physical and Climatic Regions. 

 THE THREE REGIONS OF PERU. 



The dominant physical feature of Peru is the lofty range of the 

 Andes which lies near the Pacific Ocean and forms a barrier between 

 the narrow strip of desert coast and the extensive wooded plains of 

 the Amazon. Accordingly, the country is commonly recognized as 

 presenting three naturally defined regions which differ in their phys- 

 ical features and climate ; namely, the coast, the sierra, and the forest, 

 or " montaiia," as it is called in Peru. The use of these terms orig- 

 inated with the inhabitants, and they have to a considerable extent 

 found their way into scientific literature. The name " montaiia " is 

 apt to be misleading, especially to a foreigner, since it suggests moun- 

 tains. " Selva," meaning forest, w^ould seem to be more appropriate. 

 If terms are selected which may be broadly used in considering the 

 South American continent one may appropriately speak of the Pacific 

 coastal region, the Andes Mountain region, and the Amazon plains 

 region. These terms have physiographic signification and should 

 come into use in scientific writings. The extension of these regions 

 may be learned from the accompanying map (pi. 1). 



PACIFIC COASTAL REGION. 



Definition. 



The distinction between the coast and the sierra as commonly made 

 is one of climate and is indicated by differences in agriculture. In the 

 coast the agricultural products are those of the tropical and sub- 

 tropical climates, while those of the sierra are such as are found in 

 the temperate zones. The transition from one region to the other is 

 abrupt because of the steep declivity of the Pacific slope of the 

 Andes. 



AVith the exception of the part of Peru adjacent to the Gulf of 

 Guayaquil, the division between the coast and the sierra corresponds 

 with the approximate western limit of general annual rainfall on 



