82 Bulletin American Miiseum of Natural History. [Vol. XXXVI, 



Under the first-named condition, rain usually falls from May or June 

 to November or December, and the season is termed "invierno" or winter; 

 while the months from November or December to May or June are dry and 

 the season is known as " verano " or summer. 



North of latitude 8° the seasons are characterized by one dry and one 

 rainy period; south of this latitude two rainy and two dry seasons are the 

 rule. The comparatively arid Caribbean Fauna possesses therefore but 

 one rainy season, while the humid Cauca-Magdalena Fauna has two, 

 annually. There is, however, much irregularity both north and south of 

 latitude 8°, while the amount of variation in annual precipitation at stations 

 separated by only a few miles may exceed 300 inches ! 



For example, at San Jose, thirty-seven kilometers from Buenaventura, the 

 observers of the Pacific Railway recorded a deposit in 1912 of 400.88 inches, 

 while during the same year Caldas, distant 45 kilometers from San Jose, 

 received only 54.46 inches, a difference of 346.42 inches. The topographic 

 conditions responsible for this remarkable variation will be found described 

 under the description of the route followed by our expedition No. 1. 



Ocean currents, comparative temperatures of the air over land and sea, 

 prevailing direction of the wind in relation to mountain slopes, relative 

 height of ranges in the same chain of mountains are among the more im- 

 portant local causes affecting rainfall in Colombia. The subject is inti- 

 mately related to the distribution of life and particularly to the breaking 

 up of zones into f aunal areas, but, as already remarked, few exact data exist 

 and I therefore merely present those I have obtained through the courtesy 

 of others, without further comment. 



Record of Rainfall at Paio Mines on the Rio NechS, Antioquia, from August, 



1913, to July, 1914. 



143.6 



