

On Anopheles (Myzomyia) Listoni in Calcutta. 319 . 
Piate 5. Nummulites Orbignyi, Gal. (wemmelensis, de la Harpe and van den acne 
- var. elegans, Sow. 
m, side view of a specimen from Alum Bay ; a and a’, median and transverse sections of 
specimens of the megalospheric form, from Alum Bay ; a and a’, median and trans- 
verse sections of specimens of this form from Huntingbridge ; 8, median section of a 
specimen of the microspheric form (=the WV. Orbignyi of Galeotti), from Hunting: » 
bridge. _ All x 24. 
a” and £#',central regions of sections of the megalospheric and microspheric forms (a” 
- from Alum Bay, 6’ from Huntingbridge). x 200. - 
In Plates 36”, 4a", and 5a” and f’, some indication of the presence of the canal system is: 
given, and in 5 #’, the further side of one chamber is drawn to show the perforations 
in the wall. The perforations are not present in the median planes of the tests. 

On the Occurrence of Anopheles (Myzomyia) Listoni in Calcutta. 
_ By J. R. Avie, M.B. (Lond.), Major, I.M.S., and A. Atcock, M.B., LL.D., 
F.R.S., Major, I.M.S. 
(Received April 15,—Read May 18, 1905.) 
Stephens and Christophers, in their original report* to the Royal Society, 
on the Relation of Malarial Endemicity to Species of Anopheles, state, as 
their second conclusion, “that the distribution of A. Christophersi 
[= Myzomyia Listoni] corresponds closely with an area of extremely high 
endemicity.” 
It will be remembered that they were discussing the relation of malarial 
endemia to species of Anopheles in Bengal; that they found this endemia 
to vary from 0 in Calcutta to '7 in Barrackpore, 12 in Jalpaigori, and 72 in 
' the Duars (increasing as they proceeded north); and that they concluded 
“that the distribution of certain species coincided with areas of high 
endemicity, while other species occurred, and even existed 1 in profusion, where 
very little infection was present.” 
All this is graphically illustrated in their well- known “Sketch Map ” 
(reproduced in their new book) which shows the Calcutta region marked 
Rossii, a non-malarial carrier, and the Duars marked A. _ Christophersi 
[= M. Instoni] an undoubtedly good carrier. 
Stephens and Christophers were careful to say that their observations 
relating to distribution and endemia in Bengal were conducted in June, July, 
* Malaria Reports, Sixth Series, March 6, 1902. 
