144 
MALARIA 
for A. albimanus. Since the coastal lands 
are most suitable for agriculture, there is 
a natural tendency for the rural population 
to be concentrated near sea-level, a combina¬ 
tion of circumstances which favors the 
transmission of malaria. 
During the dry season some of the sur¬ 
face collections of water may disappear. 
The current in the rivers becomes slower 
and anopheline vectors may propagate in 
algal mats which form on the surface. In 
the upper portions of the rivers, particu¬ 
larly in the dry season, the running 
streams may give way to isolated pools and 
in them anophelines find suitable breeding 
places. 
Malaria in Puerto Rico is most severe in 
the coastal plain (Earle 1930a), although it 
occasionally becomes epidemic in the foot¬ 
hills at the southern part of the island. A. 
albimanus, A. grabhami and A. vestitipennis 
are found on the island, and none of them 
occurs in abundance above an elevation of 
600 feet. In all regions where epidemics 
have been investigated A. albimanus has 
been the predominant anopheline found. 
It has a wide range of habits and breeds 
well in both temporary and permanent 
waters in the lowlands (Earle 1930a). 
A complete malaria survey of Cuba has 
not yet been made, but is now in progress 
under the direction of Henry P. Carr. In 
the first detailed report of the work to date 
(Carr, Melendez and Ros 1940) the prov- 
Figs. 6, 7. Topographical map of Jamaica. Distribution of malaria in Jamaica (from Boyd and 
Aris, 1929). 
