1920. NATURAL SCIENCES OF PHILADELPHIA. 139 



" 10-11, " "Angostura" and Frasquillo, " 

 " 13-14, " Boca Verde. 

 Upper slopes of Cordillera Occidental: 



February 23, 191S. Paramo de Chaquiro, Bolivar 

 c " 25, " Cascada Chorron. 

 Alone; Rio Antizales: 



February 25-26, 1918. Antizales, Bolivar. 

 Along Rio Esmeralda : 



February 26, 1918. Boca Antizales, Bolivar 



27, " "Las Dantas" to "Puerto Canoa," Bolivar 



28, " "PuertoCanoa" to "Salvajin." 

 Along Rio Sinu : 



March 1, 1918. Boca Esmeralda, Bolivar 

 4, " Boca Verde, 



" 5-6, " Frasquillo and "Angustura," Bolivar 



" 7-10, ." Boca Tai and Tierra Alta, 



" 11, " Morrocoquiel, " 



" 12, " "Los Hurtados," 



" 21, " Monteria, 



" 23, " Vilches, " 



" 25, " "El Pueblo," below Lorica. 

 Northern Seacoast: 



March 26-27, 1918. Cartagena and Turbaco, Bolivar 

 April 1, " Santa Marta, Magdalena. 



Of chief interest has be*en the comparison of the vegetation of 

 different altitudinal Hfe-zones, and these upon the slopes of the 

 three divergent Cordilleras of the Andes. The central axis of the 

 AndeS; entering Colombia from the South, soon divides into three 

 ranges, all of which, rising from the midst of a broad low Tropical 

 plain, reach high elevations. Also in the northeast is the wholly 

 isolated Sierra Nevada de Santa Marta. Upon each mountain 

 system, one ascends from Tropical lowland, forest or prairie (''Sa- 

 bana"), through Subtropical forest, through Temperate forest or 

 "Sabana," to the "Paramo," as the treeless chill slopes above 

 timber-line are called. Temperature and moisture cause the floras 

 of the different zones to differ, and similarly the isolation of the 

 different mountain systems accounts for a divergence in the floras 

 of the same zone on each chain. 



Dr. Frank M. Chapman, in his ''Distribution of Bird Life in 

 Colombia," has given us a masterly presentation of this problem, 

 and I adopt his system of life zones and his terminology of each. 

 As stated in his summary on page 85 of volume 36 of the Bulletin 

 of The American Museum of Natura^ History, these are: 



Tropical Zone— sea-level to 4,500-6,000 ft. (1350-1800 meters). 

 Subtropical Zone— 4,500-6,000 ft. to 9,000-9,500 ft. (2,700-2,850 



meters) . 

 Temperate Zone— 9,000-9,500 ft. to 11,000-13,000 ft. (3,300-3,900 



meters) . 

 Paramo Zone— 11,000-13,000 ft. to snow-line, 15,000 ft. (4,500 



meters) . 



