12
makes it difficult to hazard a guess as to whether it is likely to be a carrier
there or not : that it breeds in numbers in non-malarious villages does not
necessarily mean that it is not a carrier in malarious ones.
Ny. jamesii—This is the species which seems to replace Ny. fuligi-
nosus in Bombay Island, where it is very much commoner as a tank mosquito
than in Salsette. It is distinguishable from Ny. fuliginosus in having speckled
legs, and also by having certain differences in the scale markings of the veins
of the wings. Even at a glance it is possible to tell the one from the other
by the fact that Ny. fuliginosus gives the impression of having a dark wing
with white spots, Ny. jamesii of having a light wing with black spots.
This mosquito is capable of being experimentally infected in the
laboratory, though it has not been found infected in nature. It does not occur
sufficiently commonly in Salsette to make it likely to be much of a carrier in
any case.
Pyretophorus jeyporiensis.—This is not a widely-distributed species.
Only one specimen, an adult, was found in Salsette. Its markings were as
described in James and Liston.
Nyssomyzomyia rossi.—This is infinitely the commonest of the
anopheline mosquitos. Though its breeding places are such as rapidly dry up
at the end of the monsoon it was, as usual, present in houses and cowsheds in such
numbers as very seriously to interfere with the collection of more important
species. Neither in Bombay, where Dr. Bentley dissected large numbers of
specimens, nor in other places has this, the first described of the Anophelines.,
been found to be infected. Were it a carrier hardly any one would escape
Malaria.
Nyssomyzomyia punctulata.—This species is easily told from all other
Anophelines by its having half the proboscis black, and the other half white.
Adults were found in a few places in the eastern side of the island. No descrip-
tion of its larvse has as yet been published, and it was not found to hatch out
from any of the samples of larvae brought for identification in Salsette.
Myzomyia barbirostris.— This mosquito is the third commonest in the
houses and cowsheds of Salsette, and its larvse are by far the commonest in the
wells. It has a great preference for dark, shady places. It has been infected
experimentally, but has not, so far, been found as a carrier in Nature.
GENERAL CONCLUSIONS.—In the absence of dissection of cap-
tured adult mosquitos, to discover which are the carriers, it cannot be said that
any definite indication can be found from a study of the distribution of
Anophelines in Salsette. Mosquitos there are, which have a definite reputation
elsewhere as carriers of rural Malaria, but they are to be found in places that,
as tested by the Spleen Census, are quite free from Malaria, as well as in places
notoriously subject to it, and the carrier of the urban Malaria of Bombay is very
scare in Salsette.
Whatever be the carrier it is evident that something more than the
presence of facilities for breeding in abundance is required. The presence of
sufíicient dampness and shelter from the wind to enable the female to survive
in considerable numbers till she becomes infected, and, further, until the
parasite has gone through that part of its cycle which takes place in her body 9
and is present in her salivary glands, appear to be the factors which must be
present to determine the malariousness of a locality.