AMPHir.IANS AND REPTILES OF SaxTA ^NFaRTA 23 



large spreading trees, intermingled with smaller trees and considerable 

 undergrowth. However, it is not properly a humid forest, since the types 

 of trees are those of the driei* woodland, developed to a more luxuriant 

 degree, rather than those of the true humid forest, leading one to believe 

 that the moisture, on which depends its luxuriant growth, is drawn from 

 the subsoil rather than from the surface water of the rains. There is no 

 doubt, however, that the rainfall is greater south of Valle de Upar than to 

 the north of it, and these valley forests evidently extend unbroken down 

 to the Rio Cesar and thence to the Magdalena River, because the bird fauna 

 present here is strictly Magdalenan and very different from that to the 

 north of Valle de Upar. This forest (along the trail) ends very abruptly 

 at a small creek, the character of the soil changing equally abruptly, which 

 leads me to believe that the presence or absence of luxuriant forest may 

 be dependent to a considerable degree on the character of the soil, or, more 

 strictly speaking, the subsoil, which I have found to be usually an extremely 

 hard, impervious formation wherever savannas are found in the lowlands. 

 This association of savanna and hard subsoil does not, however, hold good 

 on mountain slopes. The savannas of the Macotoma Valley and elsewhere, 

 I am led to believe, are the results of deforestation and repeated, systematic 

 burning on the part of the inhabitants, rather than to any lack of humidity 

 or nature of the soil. 



As mentioned above, the flood-plain forest at Valencia ends abruptly to 

 the west, changing to scattered clumps of low trees and tangled shrubbery, 

 intermingled with areas of savanna. (PI. VIII, fig. i.j The savanna is 

 not typical, however, as certain easily recognized and characteristic species 

 of grasses and shrubs are absent. The whole plain from here on to Cam- 

 perucho is very flat, trees and shrubs become less frequent and the tract of 

 savanna larger and larger, until the woodland is confined to the immediate 

 banks of the little streams which descend at rather frequent intervals from 

 the nearby foothills. As Camperucho is approached the country becomes 

 slightly rolling and hilly, for not far beyond here the trail crosses the last 

 remnant of the great southwest spur-ridge. Here in this hilly country the 

 savannas present a truly typical aspect, true savanna grasses and shrubs 

 being present. 



Soon after leaving Valle de Upar the trail again approaches the very 

 margin of the foothills which rise abruptly from the level plain, a peculiar 

 characteristic noted from the time we left Fonseca. From here on to Cam- 

 perucho the trail is never far from the foot of the hills which present the 

 same barren aspect all the way across from Fonseca. Higher up savannas 

 abound, but from about 3,000 feet down little or no grass is present, except 

 for scattered areas, while the narrow valleys and ravines and lower slopes 

 of the valleys are slightly wooded. 



Soon after entering the savanna district, south of Valencia, num.erous 

 large palms began to appear, becoming more and more numerous until we 

 were traveling through a veritable forest of giant palms growing out of 

 clean, open savannah. This same palm, locally known as "Coroso," is 

 abundant over the whole western lowlands as far as Santa Marta, growing 



