Carriker : List of the Birds of Costa Rica. 315 



life-zones of the country, so far as my experience has enabled me to 

 determine them. With the hope that what I have attempted to set 

 forth in this paper may be of some assistance to students of ornithol- 

 ogy, I respectfully submit it to those to whom it may be of interest. 



Geography and Physiography. 



The little Central American Republic of Costa Rica lies almost 

 entirely between the parallels of 8° and n° N. Latitude, has an 

 extreme length of two hundred and fifty miles, and an extreme width 

 of one hundred and fifty miles, with an area of about twenty thousand 

 square miles. 



The greater portion of the country is very mountainous, there being 

 but narrow coastal plains on both sides, ranging in width from almost 

 nothing to twenty-five or thirty miles in the northeastern part. In 

 fact the whole of the northern portion is comparatively flat and low, 

 draining into the San Juan River and Lake Nicaragua. The drainage 

 system is complicated, large streams being numerous, especially on the 

 Caribbean slope. All these rivers have their sources high in the 

 mountains, are fed by many branches, which, descending rapidly to 

 the coastal plain, usually flow through deep narrow valleys, or gorges, 

 separated from one another by abrupt forest-clad ridges. The divides, 

 or watersheds, are usually very narrow ; while in many cases the 

 sources of streams flowing in opposite directions will overlap each other 

 on the divide. The drainage-system can best be understood by con- 

 sulting the map at the end of this paper. 



With few exceptions (these only on the Pacific slope) the whole 

 country was, and still is, to a great extent densely wooded, the forests 

 consisting of a great many species of trees of all sizes, some attaining 

 enormous girth and height. The forests of the whole Caribbean 

 watershed on account of the tremendous rainfall are much denser than 

 those of the Pacific, that is to say, there is a much greater abundance 

 of undergrowth, vines, and small trees, making the problem of pene- 

 trating them very serious, and almost impossible without the free use 

 of the machete. On the other hand the forests of the Pacific lowlands 

 are usually quite free of entangling undergrowth, the trees are larger, 

 taller, and closer together, while progress through them is compara- 

 tively easy. 



The exceptions to the forest conditions are found in the peninsula 

 of Nicoya, or more properly speaking in the region known as Guana- 



