VII. AGUE AT PARA AND HABITS OF S. FASC1ATA AND 
C. FATIGANS 
The species of Anopheles met with about the Amazon is one with white tarsi to 
its hind feet, the extreme tip of the foot being black ; it is identified as A. argyri- 
t arsis. 
It was intended to experiment with these in order to ascertain whether it was a 
favourable host for the gnat cycle of the ague parasites. Except at the commence- 
ment of our stay at Para, it was difficult to obtain larvae or pupae in abundance, and 
at the time named we were too much occupied with yellow fever. Had we antici- 
pated this difficulty it would have been well worth while to have sacrificed some time 
to the matter whilst the supply was abundant. It is, therefore, only possible to state 
that the houses near the breeding places where this species was found were all ague 
stricken ; in some cases the presence of the ague parasite was determined in the blood 
of persons from such houses. 
Two individuals of another species ( Anopheles lutzii Theo.J were taken ; this 
has unspotted wings and is all dark, with the exception of a dorsal longitudinal white 
line. None of the larvae from different pools hatched into this kind ; its breeding 
places were not found. 
The larvae of A. argyritarsis were found in small muddy pools a few inches deep, 
the largest pool was only about six feet by three feet. They were never met with 
in large or deep collections of water in pools containing obvious green algal growth. 
They are extremely active, and on the slightest disturbance seek refuge in the mud, 
so that it is possible to bale out much water with a small cup without catching a 
single individual unless some ot the mud is scooped up. It was found in practice 
that a gauze net was the best means of catching them, the individuals being picked 
out with a wire gauze spoon ; in this way one could avoid carrying much mud and 
predacious enemies, such as tadpoles and dragon-fly larvae. In all cases where 
Anopheles larvae were found they could be detected by inspection for a few minutes ; 
I never succeeded in catching any with the net in pools in which they could not be 
detected by watching. 
Observations on some pools in the proximity of some brickworks teach the 
lesson that the absence of Anopheles larvae in given pools may be temporary, and 
indeed, follow an extraordinary abundance. 
Four pools in some sand diggings, close to some brickworks, were examined on 
many occasions. There were cases of ' seisoes ' in nearly all the huts in the neigh- 
bourhood ; two huts had all the occupants sick except one individual ; one of these 
