20 Field Museum of Natural History — Zoology, Vol. xii. 



possible without a knowledge of physical conditions. Hence, although 

 the subjoined list is limited to a small part of the avifauna, it seems 

 necessary to devote some space to a brief description of the principal 

 physiographic features of the region. 



The country around the north end of Lake Maracaibo from the 

 Caribbaean shores on both sides of the Gulf of Venezuela south nearly 

 to the head of the lake, west to the base of the Sierra Perija and east- 

 ward indefinitely is in an arid division of the Tropical Zone continuous 

 with and probably to a large extent identical in character with what 

 Chapman has called the Caribbaean Fauna. It consists of three well- 

 defined subdivisions which may be called arid, semi-arid, and savanna. 

 The arid subdivision extends from the Caribbaean coast south on both 

 sides of the lake to points about 40 miles south of the city of Maracaibo. 

 Within it the soil is sandy and the growth is principally divi divi, cactus, 

 and light scrub. In general it resembles rather closely the conditions 

 found on the island of Curacao. The semi-arid subdivision occupies 

 both sides of the lake to the southward and is somewhat transitional 

 in character between the arid subdivision and the humid tropical which 

 is characteristic of the south end of the lake. It consists of light open 

 forest of fairly large trees in which the lofty Ceiba takes a conspicu- 

 ous place. Some twenty miles back from the lake shore it is replaced 

 by the savanna subdivision but reappears again along the base and on 

 the lower slopes of the Sierra Perija. The savanna subdivision, eight 

 to fifteen miles in width, roughly parallels the lake shore and the Sierra. 

 On the east side of the lake similar savanna occupies the higher ground 

 back from the lake and extends, south to the vicinity of Mendoza, south- 

 east of La Ceiba. 



The southwest comer of the lake and the whole southern end is 

 humid tropical. A broad flat plain, traversed by numerous rivers and 

 containing many cienegas and large lagoons, extends back from the 

 lake to the base of the mountains. This is heavily forested except 

 about certain estuaries where there are extensive open swamps of 

 Heliconias, rushes, and grasses. In many parts of this area the trees 

 are of immense size and the general growth reaches a luxuriance 

 seldom, if ever, exceeded. Such growth was observed along the Rio 

 Catatumbo, Rio Zulia, and Rio Guachi and doubtless is characteristic 

 of the whole region. With some modification it reaches upward along 

 watercourses far into the canyons of the mountains. Along those 

 rivers which descend directly from the mountains it continues upward 

 to meet the temperate forest. In other cases, where larger rivers have 

 broken through or passed arotmd the main mountain wall, the humid 



