BACOT : MOSQUITOES AND THE DANGER OF MALARIA. 249 
resemblance to Anopheles maculipennis, by reason of the spots 
on its wings, though it belongs to the Culicidae. This insect 
must be distinguished with care from the much more dangerous 
•species. 
Just as all the available evidence points to Anopheles 
mosquitoes as being alone responsible for Malaria, so also does 
it point to certain Culicince as the sole responsible agents 
in the case of yellow and* dengue fevers—the former being 
definitely proved as due to the presence of Stegomyia fasciata ; 
while the latter, though formerly thought to be due to Culex 
fatigans, is now said to be conveyed by the same mosquito as 
yellow fever. C. fatigans is, however, definitely incriminated 
as conveying Filaria bancrofti, the causative agent of elephan¬ 
tiasis. There is, in the case of this disease, evidence which 
•suggests that certain Anopheles mosquitoes, as well as Stego¬ 
myia fasciata, may also be incriminated ; for the embryonic 
forms of the worms which block the lymphatics and thus cause 
the characteristic swellings are found occasionally in the thoracic 
muscles of these mosquitoes. 
As we are concerned in this country only with Malaria (or, 
to use its old English name, “ Ague ”), I do not propose to 
deal further with these other diseases, but will confine myself 
to the incidence of Malaria and the mosquitoes which convey 
it, and will conclude with some general remarks on the local 
distribution of mosquitoes and on methods for their control. 
The eggs of Anopheles mosquitoes are deposited singly (PL vi., 
1 and 2). Although they may collect into small groups on 
the water-surface, they are never cemented together into rafts. 
They can be distinguished at once from those of all other tribes 
of mosquitoes by their side frills or floats. Generally, if not 
always, thev float until hatched and are unable, so far as is 
known, to resist desiccation or defer hatching after incubation, 
as do the eggs of the yellow fever mosquito and its relatives. 
The larvae (PI. vi.—3 and 4) may be distinguished at once 
by the fact that they have no syphon tube, and that, when at 
the surface of the water, they rest in a horizontal position, 
while the larva? of other tribes hang head downwards by their 
•syphon tubes in a more or less vertical or oblique position. 
Further distinguishing features are the star-shaped processes (PI. 
vi., 5), a pair of which are present on the dorsal area, of the 
