Tropie Zone: Costa Rican Region. 669 
Such types as Pinus, the Cactaceae, the Piperaceae are little represented 
in the flora of Costa Rica and still less in Panama. The flora of the high- 
lands of Costa Rica shows affınities with that of Mexico and may be consi- 
dered to be a southern extension of Mexican types mingled with those 
of a different region. The primeval forests on the eastern slopes of the Cor- 
dilleras consist of plants represented in the flora of Columbia and Venezuela, 
while that on the Pacific coast of Costa Rica is essentially the same as in 
Panama‘). The flora of Chiriqui is essentially the same as that of eastern 
tropic South America, except in the higher regions between 8,000 and 
9,000 feet where, as we have seen, a certain number of species occur which 
are either common to Mexico and Guatemala, or peculiar. The characteristic 
species which enter into the Chiriqui flora, as well, as the whole of the Costa 
Rican phytogeographic region, approach most nearly to those of Brazil, Guiana 
and the coasts of Venezuela and Columbia. Species in common with West 
Indian ones are also found. The Chiriqui flora has very little in common 
with Guatemala and Mexico and still less with Ecuador and the Andean high- 
lands?). Lastly, we have no knowledge of any species of Yucca, Nolina, 
Dasylirion, or Beschorneria south of Guatemala; and records of these genera; 
as well as for Furcraea and Agave, are very few for the territory south of 
Mexico. The last two genera probably enter the Costa Rican region, yet the 
evidence of such distribution is scanty. The following formations contain 
examples of the mixed character of the South American type of the Rain 
Forest Formation with the North American one of oaks and alpine elements. 
FHylaea Formation. The entire territory drained by the San Juan River in 
Nicaragua is covered with tropic forests of extreme density and impenetrableness. 
The trees are very tall and from eight to fourteen feet in diameter, not placed 
so closely as in our northern forests, but the spaces between are covered with 
shrubs and vines and numerous other plants together with parasites and 
epiphytes (ferns, bromeliads, mosses) which cover the branches and trunks of 
the trees®). On account of the unusually luxuriant character of the vegetation, 
POLAKOWSKY*) suggests the name Hylaea for this type of forest growth and 
this name Pittier applies also to the entire Atlantic forest of Costa Rica, 
attributing to it a South American character. 
The Atlantic slope with more constant humidity of air is characterized by 
vast, dense, evergreen, virgin forests (Tropic Rain Forest Formation). 
The tangle of vegetation is so great that the interior of the country can 
1) POLAKowskYv, H.: Petermanns Mitteilungen 1877: see Bibliogr. p- 85- e 
2) WAGNER, Dr. Morıtz: Physisch-geographische Skizze der Provinz Chiriqui. Petermanns 
Geographische Mitteilungen 1863 pp. 280—299, translated by HEMSLEY. Y: 
3) SHIMER, B.: A Forest in Nicaragua. Popular Science Monthly 1894. rs : 
4) PoLAKowsky, H.: Die Pflanzenwelt von Costa Rica 1879, loc. eit. p- 45; u 
Portant recent book and paper: PırrıEr, H.: Ensayo sobre las Plantas usuales de 
Washington 1908, and WERCKL£, CArLos: La Subregion Fitogeogräfica Costaricense. 
Costa Rica. 1909. 
857- 
San Jose, 
