4 IQ Bulletin American Museum of Natural History. [Vol. XX, 



are the rivers Cordova, Frio, Gaira, Manzanares, Piedras, 

 Buritaca, and Don Diego. The only swamps are those of the 

 Magdalena estuary, some small patches along the lower 

 courses of the rivers, and the mangrove thickets. 



With the exceptions noted below the whole region is covered 

 with forest; but there are two strongly contrasted growths, 

 which I distinguish as mountain forest and dry forest. Lo- 

 cally these are called mata and pampa, the latter term, in 

 this region, including dry forest as well as grass lands. 



The true mountain forest is a matted growth of trees and 

 vines with numerous epiphytes and ferns; very few trees 

 shed their leaves at stated seasons, and the forest is damp and 

 verdant throughout the year. In the dry forests, on the con- 

 trary, nearly all the trees and vines are leafless during the 

 latter part of the dry season, February to May; the few 

 peculiar ferns die down to the roots. Grasses and herbs are 

 abundant wherever the ground is not too shady, but they 

 wither during the dry months. The distinction of plant 

 species is almost complete, and is all the more remarkable be- 

 cause the two kinds of forest exist side by side; during the 

 rainy months an unpractised traveller will hardly note that 

 he is passing from one flora to another; but in March the 

 dry forest is almost leafless, while the other is green and 

 luxuriant. 



The extreme summits of the San Lorenzo Mountains are 

 generally without large trees, the low growth consisting of 

 bromelias, ferns, bushes, etc. But with these exceptions the 

 mountain forest covers everything down to a level of about 

 2000 feet above the sea; below that it extends in narrow lines 

 along the river shores, sometimes to the coast. Further east, 

 near Don Diego, the mountain forest comes down bodily to 

 the seashore or near it. 



The dry forest covers most of the remaining country, 

 sometimes with a heavy growth of high trees, sometimes 

 lower and more open ; on dry hills near the coast it becomes 

 'scrub,' seldom over twenty-five feet high, but with little 

 change of plant species. In the river valleys it is generally 

 separated from the water by a thin line of trees like those of 



