NO. 5 MAMMALS OF PANAMA GOLDMAN 21 



Sapo forms a prominent but little-known ran,ije extending from 

 Garachine Point at the southern entrance to the Bay of San Miguel, 

 southward along the Pacific coast to a junction with the main range 

 near the international border. 



Aside from the higher mountain ranges that form the Isthmian 

 backbone, a multitude of rather steep, extensively eroded ridges 

 separating narrow river valleys ramify throughout the greater part 

 of the republic. Extensive and fairly level plains occur at various 

 elevations, however, in the province of Chiriqui and along the Pacific 

 coast from the Bayano River west to the Canal Zone. 



Owing to the narrowness of the Isthmus most of the rivers are 

 short, and from their sources commonly interdigitating along the 

 opposite sides of the deeply eroded continental divide, flow directly 

 to the sea, but there are several notable exceptions. All of the larger 

 rivers of South America, including the Atrato, flow into the Atlantic; 

 it is therefore of interest to note that in eastern Panama the course 

 of the major streams is reversed in conformity with the abruptly 

 altered trend of the continental mass, and a shifting of the crest 

 from the Pacific to the Atlantic side along the Colombian frontier. 

 The greatest river system of the republic is the Tuyra-Chucunaque. 

 After draining a large and very humid area, these two rivers unite 

 near the middle of the Isthmus and in combination with several other 

 large streams pour an immense volume of water into the Gulf of 

 San Miguel. The second river of the republic in point of size is the 

 Rio Bayano, which takes a westerly course and joining the Rio 

 Mamoni, a much smaller stream, turns southward and under the 

 name Rio Chepo enters the Bay of Panama. The most important 

 river of the Atlantic drainage is the Rio Chagres, whose watershed 

 is an interior basin. The general course of the stream is westerly to 

 a point near where it enters the Canal Zone and bends north to the 

 Caribbean Sea. The Chagres, whose waters are now impounded in 

 Gatun Lake, 164 square miles in area, furnishes the water for oper- 

 ating the locks of the Panama Canal, and through the locks at the 

 southern end of Gailliard Cut a part of its flow is diverted into the 

 Pacific Ocean. 



While climatic conditions vary considerably in dififerent parts of 

 Panama, the region as a whole is subject to the influence of two 

 annual seasons, the duration of which are correlated with the direc- 

 tion of the prevailing winds. During the so-called " dry " season 

 the northeast trade wind blowing daily from about the month of 

 December to the month of May, at times with considerable violence. 



