252 
Malaria at Morib 
The relative prevalence of the different anopheline species is indicated 
by the numbers of each captured at Morib within a space of nine 
days: 
(1) 
ludlowi 
236 
of which 
90 
were 
$ 
(2) 
umbrosus .. 
39 
99 
38 
99 
? 
(3) 
rossi 
36 
99 
15 
99 
? 
(4) 
sinensis 
1 
99 
1 
99 
$ 
(5) 
tesselatus 
1 
99 
1 
99 
? 
What we know of the relative infectivity of these species in other 
places, is as follows: 
(1) ludlowi: Christophers, in the Andamans, found 2/53 of this 
species infected; it is thought that the parasites which de Vogel found 
in a rossf-like mosquito were really found in ludlowi. Horne in India 
has also reported finding ludlowi infected. 
(2) umbrosus: Watson has found this species infected, but he 
does not state what proportion were infected; it is reported that it 
has also been found infected in Borneo. Stanton found that of eleven 
specimens which had been exposed to infection not one was parasitised. 
I had previously examined about six of these mosquitoes with negative 
results. 
(3) rossi: Eysell contends that several observers have found this 
species infected, but it seems doubtful whether the species has not been 
confused with ludlowi. Stanton dissected 136 specimens but found 
none parasitised. 
(4) sinensis : this species certainly becomes parasitised (Tsuzuki, 
Kinoshita). Stanton found zygotes in two out of ninety-eight speci¬ 
mens which had been exposed to infection. 
(5) tesselatus: nothing is known regarding the behaviour of 
malaria parasites in this species. 
To these data may be added the result of my dissections at Morib 
as follows: 
ludlowi .. 
umbrosus 
rossi 
sinensis 
tesselatus 
No. examined 
No. found infected 
80 
0 
38 
0 
13 
0 
1 
0 
1 
0 
Conclusions on relative infectivity drawn from these figures would 
certainly be fallacious. It is very probable that rossi, if infective, is 
