NATURAL AREAS AND REGIONS 



641 



the richest and most variegated that I 

 have ever seen; the smaller birds, such 

 as the flycatchers, parrakeets and 

 hummingbirds, are especially prevalent. 

 The mollusc fauna has more Antillean 

 and Central American elements (such 

 as the Urocoptidae and Pomatiasidae) 

 than does that of the Andes. Arboreal 

 snails {Drymaeus, Auris) are common, 

 while the ground fauna may be exempli- 

 fied by Poteria and the smaller species 

 of Pleurodonlc. From the standpoint 

 of the terrestrial animals, two quite 

 noticeably different types of forest can 

 be distinguished: that with a rich leaf- 

 humus, and that witli a leached-out 

 root-humus. This difference affects 

 even the arboreal snails, as many of 

 these aestivate on the ground. 



The eastern prolongation of the 

 Cordillera Oriental of the Andes is 

 quite markedh' different, both geologi- 

 cally and faunisticly, from the Carib- 

 bean System, from which it is separated 

 by the semidesert region around Bar- 

 quisimeto (Cf. Sievers, 1. c). The 

 appearance of the tropical rain-forest 

 is verj^ similar although larger trees 

 are more prevalent and larger areas 

 are almost completely dominated by 

 tree ferns or palms (root-humus). The 

 scarcity of fan-palm and the rich growth 

 of the similarly leaved Carludovicae 

 among the Heliconiae of the stream 

 borders, are conspicuous differences 

 from the flora of the north-central 

 mountains. In the moUuscan fauna 

 the Urocoptidae and Pomatiasidae are 

 absent, in the region studied, and the 

 prevalence of Streptaxidae is notable. 

 The species are closely related to those 

 of central Colombia. The smallest, 

 rocky brooks are often overgrown with 

 Cyclanthaceae and, although poor in 

 specific diversity, contain numerous 

 individuals of Heieragrion and Philo- 

 genia (Odonata) ; Pachychilus (Mol- 

 lusca) is abundant in the western moun- 

 tains but absent in the Andes. The 

 creeks of the larger valleys are scoured 

 by the torrential floods of the rainy 

 season, and have a very barren fauna. 



3. Montane forest. The temperate 



rain forests occupy the middle belt of 

 the mountains, not at a fixed altitude, 

 but where the condensation of the water 

 contents of the ascending air masses 

 takes place. During the day, this belt 

 may be easily perceived by the distant 

 observer owing to the broad strip of 

 clouds, which stretch horizontally across 

 it, their base, well defined, ascending 

 or descending with the increase and 

 decrease of temperature. Most of the 

 species which form these forests are 

 hygrophytes. The trees have a weakly 

 developed root-system; their leaves are 

 ample and often provided with dripping 

 points and hydatodes. The epiphytic 

 flora is unusually rich, but the lianes 

 are not so abundant as in the tropical 

 rain forest. 



On account of the diversity in their 

 altitude, the flora of these temperate 

 rain forests changes considerably from 

 one place to the other. It would take 

 too much of our limited space to enu- 

 merate even the principal species in 

 each case. Generally speaking, the 

 Lauraceae seem to be the dominating 

 family. Typical of their kind are the 

 beautiful forest around Colonia Tovar 

 in the Coast Range, the flora of which, 

 though investigated again and again, 

 still seems to be inexhaustible in new 

 species. In this region we note, among 

 many others, Cedrela montana, Guarea 

 mollicoma, G. Ruagea, Esckweilera fend- 

 leriana, Weinmannia glabra and Escal- 

 lonia floribunda, which attain here 

 arboreal dimensions, Protium laxiflorum, 

 P. icirariba, Sapium stylare, Styrax 

 macrotrichus, Podocarpus coriaceus, P. 

 Harmsianus, etc. Also quite a number 

 of striking species of palms such as 

 Oenocarpus altissimus, Oe. caracasanus, 

 Oe. utilis, Ceroxylon Klopstockia, and 

 at least three Iriarteas. Lesser trees 

 or shrubs are J lex myricoides, Allophylus 

 excelsus, Guettarda tovarensis and Aegi- 

 phila verrucosa. Under these trees, 

 perpetually dripping and shrouded in 

 mist, there grows again a world of ferns 

 and lower Crj^ptogams, excluded in 

 places by large colonies of the giant 

 grass Planotia nobilis. No less marvel- 



