2 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL. 62. 
southerly winds and tropical showers, and these increase throughout 
the summer, nearly every day having its afternoon tropical down- 
pour. Except for the slightly drier belt along the Pacific coast very 
little of the country is cleared, and then only along the rivers. Most 
of it, probably about 99 per cent, is tropical rain forest of mixed 
angiosperms. Some cane, oranges, and cocoa are cultivated and much 
chicle is gathered, but the population is sparce except along the south 
coast and in the uplands to the east and west of the low country of 
the isthmus, and trails are few and poor. 
The shores are skirted with thickets of Leguminosae, coco-palms, 
and Hippomane. Low shores and inlets are covered with mangrove 
plants (Rhizophora, Avicennia, Conocarpus, etc.) and the less saline 
marshes abound in Acrostichum, Crescentia, etc. Prominently repre- 
sented in the existing flora of the isthmus are various species of the 
families Lauraceae, Myrtaceae, Anacardiaceae, Anonaceae, Legu- 
minosae, Sapotaceae, Malpighiaceae, and Meliaceae. Species of the 
following genera are especially characteristic: Acrostichum, Cocco- 
lobis, Lonchocarpus, Haematorylon, Inga, Dalbergia, Ficus, Banara, 
Fagara, Cedrela, Achras, Leucaena, Erythrina, Crescentia, and Exos- 
tema. Six of these genera are represented in the Miocene flora of 
this region. 
The described fossil flora comprises 33 species, all but 4 of which 
are new. There are 2 ferns, 1 monocotyledon, and 30 dicotyledons. 
The last represent 11 orders and 20 families. The largest order is 
the Rosales, with five families and seven species. The orders Gerani- 
ales, Thymeleales, and Myrtales follow, with four species each. The 
largest single family is the Lauraceae, with four species, and the 
families represented by more than a single species (two each) are the 
Moraceae, Melastomataceae, Apocynaceae, Bignoniaceae, and Rubi- 
aceae. 
The fossil flora, like that of the recent lowland flora of the same 
region, is essentially South American in its facies. It is strictly 
tropical except for the presence of Liquidambar fruits, representing 
a genus still present near by at elevations over 800 meters, and 
which may have been washed into the basin of sedimentation from 
Miocene uplands near at hand. 
Too little is known about the fossil floras of the Tertiary of tropical 
America to enable precise age determinations to be made. Intrin- 
sically the flora obviously belongs in the Neogene division of the 
Tertiary. The only species positively identified which has an outside 
distribution is Nectandra areolata which occurs in Colombia and in 
the Miocene of Costa Rica. Less certainly determined forms with 
an outside distribution are Ficus talamancana and Goeppertia ter- 
tiaria, which occur in the Miocene of Costa Rica, and Guettarda cookei, 
which occurs in the Miocene of the Dominican Republic. The fossil 
