( 262 ) 
Notes on the Mosquitoes on the River and Coast Districts 
of the Eastern Side of the Peninsula. 
By C. W. Daniels, m.b., m.r.c.s. 
The rivers on the eastern side of the watershed are comparatively free 
from mine tailings but in rainy weather are muddy to some extent. * The 
Pahang River is the largest, but observations were also made on the 
Kuantan River. One point of resemblance to such African rivers as the 
Zambesi is that the common mosquitoes belong to the Mansonia. The 
commonest species however is not uniformis as on the Zambesi though it 
does occur but cinnulipes and a third species M. aunulata is also found. 
These mosquitoes were much less numerous than on an African river. 
Stegomyici scutellaris was common in some places and in the vicinity of lar^e 
settlements only and therefore to be attributed to them Culex fatigans. 
Anopheles were not found on the boat moored up to the banks during 
fi\ e nights spent on the Pahang River or in two on the Kuantan Riv r er and 
°nl) in the lower reaches were any anopheles larvae found in pools near the 
bank and none were found in the river or pools in connection with the river. 
This is in marked contrast with African rivers where such mosquitoes 
abound. Considering that several species of anophelina A. Treacherii, 
A. cilbirostris , A. willmovi and A. Karwari are found in streams only and that 
at least two of these species are abundant in the streams supplying these 
rivers their absence in the rivers requires some explanation. In the water 
from the Kuantan the larvae can live and probably also in long stretches 
of the Pahang River. The absence of any grass, reeds or sedges growing 
into or on the surface of the rivers is the probable explanation. Such 
grasses abound in the African rivers and the larvae are found in the water 
between the stems and submerged roots. This form of vegetation prevents 
the larvae from being carried away, protects them from fish and probably 
provides them with food supply. 
It is of great importance that the importation of such grasses should 
be prevented. Malaria on the banks of rivers except towards their mouths 
is not common or virulent. In Africa such banks are on the*East coast 
the worst placed for malaria. The introduction of grasses of this character 
might and probably would result in an enormous increase in the unhealthi¬ 
ness of a thickly populated portion of the country. 
I he common larvae found in the pools were C. gelidus, nigrocephalus 
and fatigans. Near the coast the. river broadens out and sand banks are 
numerous and there are backwaters. The numbers of mosquitoes is 
larger especially of those belonging to the genus Mansonia. No anopheles 
were found in the river and those found on shore are not river breeders. 
At the town of Pekan the anophelina M. Rossi, C. Kochii, M. Sinensis and 
M. Umbrosus were found as adults and breeding in pools and more or less 
stagnant water in and near the town. In this town the commonest 
mosquito was still Mansonia annulipes but Culex fatigans and Stegomyia 
scutellaris and M. uniformis were also common. Culex gelidus and biauratus 
