Tropic Zone: Guatemalan Region. 665 
Cohune Ridge Formation?). Between the pine ridges and the rivers are what are 
called cohune ridges in consequence of the predominance of the noble cohune palm, Attalea 
cohune (see plate V at p. 304). The distribution of this palm is affected by the near presence 
of running water, for it often monopolizes the banks of rivers and is not so generally represented 
farther away. It is found vegetating in clumps, small and large together, over which are masses 
of thick, woody creepers. Associated with this tree is the mahogany, Swietenia mahagoni. 
Ferns are abundant in the shady depths of this forest though there appears to be only one tree 
fern, Alsophila. — 
Pine Ridge Formation. The tree which occupies almost exclusively the 
dry gravelly soil of the broken ridges is Pinus caribaea (= P. heterophylla = 
P. cubensis), a species which has the northern limits of its distribution in 
South Carolina. Except in the narrow valleys, the forest of this pine is a 
fine one. One hundred and one trees have been counted to the acre and the 
growth is tall and straight. In some places, the pine ridge plants give place 
to groves ofoak, probably Ouercus virginiana, and some of these oaks attain 
great size. This pine ridge formation, according to SAPPER®), occurs in Bri- 
tish Honduras on the central Monkey River, in Guatemala southeast of Lake 
Peten, on the shore of the Sea of Yzabal. In Honduras, the pine ridges occur 
in isolated localities such as at Trujillo on the north coast, while stretching 
from the Brus Lagoon on the north shore to the Rio Grande (Nicaragua) in 
latitude 13° is a broad continuous strip characterized by the dominance of 
the plants of this formation alone. ‘This strip reaches its greatest width on 
the Coco River (Nicaragua) extending from the littoral forest on the east to 
the tropic rain forest at S. Geronimo on the west. In general the littoral 
forest bounds the forests of Pinus cubensis on the east and northeast, but in 
several places the tropic rain forest is interposed. On the Pacific slope this 
formation is not represented. 
Pine- and Oak Forest Formation. This formation in large part covers the 
south central part of Guatemala equally on each side of the 15° north lati- 
tude, extending into the province of Huehuetenango quite to the 16° north 
latitude with an eastern arm following the Rio Motagua beyond the Sea of 
Yzabal. Southeastward, this formation extends into San Salvador, north of 
the Savanna Chaparral formation. The whole of the central part of Hon- 
duras, as far east, as west longitude 85° 30’ is occupied by the oak-pine 
forest, except where its continuity is broken by savannas, chaparrales, tropic 
rain forests and the like. In general, this formation occupies a country wit 
a pronounced dry climate conditioned by the direction of the mountain 
chains which influence the distribution of rain. The drier the local climate, 
the more does the pine predominate over the oak, and conversely, but in 
Honduras the pines seem to be more widely distributed than in Guatemala. 
and two meters yearly, but this 
The rainfall i i ines is between one 
ainfall in the region of oaks and pines 15 anni 500 
amount may be modified by local conditions. On the Paeifie 
ee 
1) Hooper, E. D. M.: See Bibliography p. 84- 
2) Sarper, K.: See Bibliography p. 86: Guatemala: see Bibl. p. 85. 
