320 - Majors J. R. Adie and A. Alcock. [Apr. 15, 
and August, and though they came to the general conclusions quoted above 
they insisted that much more extended observations were required. 
In the second edition of their book,* just published, this generalisation is 
repeated—*“ We may have countless numbers of Jf. Ross: as in Calcutta 
(environs) and get a malarial index of 0, and this appears to hold good in 
Madras, Bombay, and, as far as our observations go, universally. On the 
other hand, where we find JZ. Listoni, M. culicifacies, P. Jeyporensis, in India 
we have a high endemic index.” f 
This preface is necessary in order to realise the importance of the discovery, 
lately, of M. Listont in Calcutta. 
During the last Christmas holidays we found, in the Museum tank in 
Calcutta, considerable numbers of Anopheles’ larvee, which were immediately 
examined, and referred to the mgerrimus and culicifacies groups. On 
breeding out, these were found to be JZ. nagerrimus and M. Listont, the former 
being much more numerous. The larve were found in shady spots near the 
bank, chiefly near and under a raft. There was abundant aquatic vegetation 
and fish (Cyprinidae, Saccobranchus, and Ophiocephalus) are numerous ; it was, 
in short, an ordinary Calcuttatank. Our specimens show very well the palpal 
bands as described by Stephens and Christophers, “ palpi, two broad apical 
bands . . . . . one narrow basal.” 
This capture, in the first place, extends the geographical distribution of this 
species given in the books. It is the only malaria-carrier that has been 
reported from Calcutta, other Anopheles being Rossi, fuliginosus, nigerrumus, 
Stephenst. In the next place it seems to show—as, indeed, would be expected 
a priort—that generalisations as to seasonal prevalence of specific Anopheles 
and endemic indices deduced therefrom, can only be made with confidence 
when observations are carried on throughout the year. 
“Endemic index” is described as the percentage of infected children in any 
district, and in the investigations of the Malaria Commission the figure 0 
for Calcutta was arrived at by the examination of only 191 children in June, 
July, and August, and was regarded as confirmed by the absence during those 
months of all the known malaria-carriers. 
_ Now, however, that the approved malaria-carrier Anopheles (Myzomyia) 
Instoni is known to be present in Calcutta in December and January (none 
have been found in February) it seems reasonable to suppose that the June— 
August observations may have merely coincided with the trough of a then 
dormant endemic curve for Calcutta. This would be agreeable to clinical 
* ¢ Practical Study of Malaria,’ p. 258. 
+ See also Malaria Reports, Series VII, p. 23. 
{ P. 195, new edit. 
