General and local distribution. 



which occurs in Java, the Malay Archipelago, Old Calabar, &c. , and 

 A. maculatus, which occurs in China. The group of Indian species, 

 including A. listoni and A. culicifacies, is also very near, if not iden- 

 tical with, the African group, including A. funestus and its allies, 

 and the unspotted winged species A. aitkeni is a near neighbour 

 of the European species A. bifurcatus, and the Algerian species 

 A. algeriensis. It would seem, therefore, that many of the Indian 

 species have a wide distribution in nature. But a distinction must 

 be made between the general distribution of a species and its dis- 

 tribution in the particular countries where it occurs. There seems 

 no reason to doubt that some "anopheles," such as A. rossi, do not 

 habitually act as carriers of malaria in nature. To whatever cause 

 this is due whether to the fact that such species have become 

 immune to the malaria parasite, or because they habitually feed on 

 the blood of domestic animals rather than on that of man it is the 

 chief reason why a knowledge of the local distribution of individual 

 species is so important. Although the geographical distribution 

 of a species may be wide, its local distribution may be very limited. 

 A. listoni, for example, though it has been found in India as far 

 north as the foot of the Himalayas and as far south as Goa in the 

 Bombay Presidency, is quite unknown in the Punjab. A. rossi and 

 A. stephensi, also, though they are very common in Calcutta, are 

 very rare or absent in many parts of the Duars, which is only a com- 

 paratively short distance away. A. jeyporiensis, again, has been 

 found up to the present only in two districts, namely, the Jeypore 

 agency in the Madras Presidency, and Nagpur in the Central Pro- 

 vinces ; and A. elegans in only one place in the Bombay Presidency. 

 It even happens, not infrequently, that the anopheles fauna of two 

 places only a few miles apart is entirely different. In some cases this 

 localized distribution of species is due to differences in the charac- 

 ter of breeding grounds. In Calcutta, for example, almost the only 

 breeding places are ponds and pools of water the favourite breed- 

 ing grounds of A. rossi, while in the Duars the prevailing breeding 

 grounds are running streams the favourite breeding places of A f 

 listoni. Climate is also an important factor, as in the cases of A. 

 lindesayi and A. gigas, which are found only in hill districts, and a 

 particular kind of food supply may also have some influence, as in the 

 case of A. rossi, which is never found very far from human dwellings. 

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