76 Bulletin American Museum of Natural History. [Vol. XXXVI, 



arid, covered with wild dense jungle growth, and so deeply ravined as to be 

 impassable. These merge into the low Llanos, over which are scattered 

 Savannas, immense meadows of fine succulent grasses, dotted with high 

 bushes, clusters of palms, and thickets of other trees. During the wet or 

 winter season, much of the land is subject to inundation, and consequent 

 fertilization, by the swollen rivers." 



Hettner,^ writing of the country lying at the eastern and western bases 

 of the Eastern Andes in the Bogota region, describes the Llanos and accounts 

 for their lack of forests as follows : 



"The two lowlands which take in the western and eastern foot of the 

 Cordilleras, bear altogether different plants; the lowland of the Magdalena 

 River below Honda is covered with a thick, primeval forest; the eastern 

 low-lands, the so-called Llanos, are on the other hand, wide grassy plains, 

 which are only interrupted by a line of forests on the banks of rivers. This 

 difference of plant growth has a relation with the rainfall, for the lowland 

 of the middle part of the Magdalena River has two rainy and two dry 

 seasons, which are, however, of short duration; in the Llanos, on the other 

 hand, the one dry season shrinks together to a few weeks, while that of the 

 other is extended to from five to six months. With so long a dry season 

 near the equator, the forest growth is out of the question. If we should 

 travel southward in the Llanos and reach the territory of the equatorial 

 rains, we should find here likewise a luxuriant forest, and vice versa, at the 

 lower part of the Magdalena River, somewhat north of 8 degrees, where 

 the tropical rains begin, the forest is gradually crowded out by grassy plains, 

 interspersed with single trees, or in other words, by savannas." 



The Caribbean forestless region corresponds to the Caribbean faunal 

 area. It is a semi-arid or arid region in which the absence of forest-growth 

 is presumably due to insufficient or irregular rainfall with long periods of 

 drought. 



The coast region itself, from the Rio Sinu to the Goajira Peninsula, 

 except for the mangrove-bordered lagoons, and the section of forest-covered 

 shore north of the Sierra Nevada of Santa Marta, may be described as arid. 

 Cacti, thorn-bearing bushes and other xerophilos forms comprise its char- 

 acteristic vegetation. Farther inland we pass to the semi-arid savannas, 

 a grazing country with scattered mimosas and acacias and frequently 

 marshes. 



Carriker writes: "The semi-arid coast belt begins a few miles south of 

 Cienaga (town on the Santa Marta Railway) and extends around the coast 



1 ' Die Kordillere von BogotS,' Petermann's Mittheilungen, Erganzungsband, 22, p. 76. I am 

 indebted to Dr. Chester A. Reeds for this and following aj^stracts from Hettner's valuable paper. 



