466 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1911. 
Atlantic slopes and to the high mountains. Thus, in the mountain- 
ous parts of eastern Guatemala (Alta Verapaz), where according to 
the native saying ‘‘it rains 13 months out of every 12,” tree ferns 
are exceedingly abundant, a few species occurring at and near sea 
level, but the most of them at from 4,000 to 6,000 feet altitude. 
West of this region, in the dry interior basin, they are wanting; and 
only two species, Cibotium Wendlandt and Hemitelia costaricensis, 
are reported from the higher region near the Pacific, even the moist 
forest belts of the volcanoes Fuego and Agua having none, so far as 
known. 
In Costa Rica a relatively small number of tree ferns are found in 
the moist Atlantic lowlands, but they are elsewhere of very general 
occurrence, excepting only the half desertlike slopes facing the Pacific 
and the dry and open portions of the interior table land, which has 
a temperate and delightfully equable climate. The latter area 
(meseta central) is relatively small, and one has only to go out a few 
miles to the lower mountain slopes to find tree ferns m profusion. 
The greater part of Costa Rica, however, and by far the most inter- 
esting, is the exceedingly broken, mountainous region to the north- 
ward, from which rise the four great volcanic peaks Turrialba (11,128 
feet), Irazti (11,312 feet), Barba (9,412 feet), and Poas (8,786 feet), 
from east to west. These intercept most of the moisture from the 
Gulf, and it is here that the Cyatheacee reach their highest develop- 
ment, both as to species and size and number of individuals, in any 
part of North America. Christ, indeed, regards it as ‘‘the richest 
tree fern region of the world.” Certainly it is an endemic center of a 
high order, and when adequately explored is likely to yield many 
more than the 50 species it is now known to contain. It embraces 
altitudes above 5,000 feet; and although snows are wanting from all 
Costa Rican volcanoes, heavy frosts occur more or less regularly from 
6,000 feet upward. The extremes of temperature endured by the 
tree ferns of this region must be very great. 
Chiriqui, the westernmost Province of Panama, apparently does 
not differ greatly from Costa Rica as a tree fern region. Although 
there are a few coastal species, here also the great majority are found 
in the high mountains, which form a definite cordillera paralleling 
the coast line, east and west. Recent exploration has shown that 
they are mainly those known hitherto only from Costa Rica. The 
Cordillera gradually decreases eastward, until in the Canal Zone only 
three or four lowland tree ferns are found. One of these, Hemitelia 
petiolata, first described from Panama, is common in ravines and wet 
thickets. 
In Mexico, also, as might be expected, tree ferns are wanting from 
the interior, arid, high plateau region, whose flora has been so thor- 
oughly investigated during the past 35 years. Upward of 20 species 
