878 JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, Vol. XVI II. 



Fourthly, we collected a number of mosquitoes in the neighbour- 

 hood ; we observed that anopheles were abundantly present. An 

 examination of these showed that two species were found, viz., 

 Anopheles rossii and Anopheles stephensi. Now the former mosquito 

 can be captured all over Bombay : moreover it has been examined in 

 large numbers on many occasions, but has never been observed to be 

 infected in nature, so that this mosquito did not seem to play any part 

 in spreading the disease. Anopheles stephensi on the other hand 

 has never been found by me in Bombay before. It has since been 

 captured only within the limits of the present epidemic area. We 

 have dissected a large number of these mosquitoes, caught chiefly m 

 the Frere Road : nearly 25 per cent, of them harboured the malaria 

 parasite in some stage of development. This discovery is particularly 

 interesting, not only because it is the first time that this mosquito has 

 been observed to be infected in nature, but also because the other 

 species which have been found infected in India, viz., Anopheles 

 listoni and Anopheles cvlicefacies have been mosquitoes which breed 

 in flowing water— in streamlets and irrigation canals, while this 

 mosquito, Anopheles stephensi, generally breeds in still water — in 

 wells, in cisterns, in chatties and in tinpots. Moreover, it assumes 

 an additional interest in view of the fact that the present epidemic 

 seenis to be associated in some way with the construction of the New 

 Docks. Earthworks of this nature have very often been associated 

 with severe malaria, and if for no other reason than to guard against 

 such eventualities in the future, the present epidemic ought to be 

 thoroughly investigated. 



I have said that this epidemic of Malaria is associated with the 

 presence of two species of anopheles, the one harmless, while the 

 other is responsible for spreading the disease. It is of importance, 

 therefore, to distinguish these mosquitoes from one another. They 

 can be diiferentiated from one another in the stages of imago, larva, 

 and egg. The fully-developed mosquitoes, as you will see, somewhat 

 closely resemble one another ( Plates B and C ) ; but a more careful 

 inspection will reveal the fact that Anopheles stephensi 'is rather greyer 

 than Anopheles rossii which has a somewhat brownish hue. With the 

 naked eye or a hand lens you can readily observe that the marking on 

 the palpi of the two mosquitoes differs. Anopheles stephensi has two 

 broad white bands towards the tips of the palpi separated by a narrow 



