132 Ww. M. GRAHAM—RESULTS OBTAINED FROM A MONTHLY EXAMINATION 
has been used for washing clothes, &c. It is very frequently associated with 
S. fasciata in the same vessel and, like it, is found in both pots and barrels. It is 
commonest in pots, probably because the foulest water is usually found in these 
vessels. arly in the investigation my attention was aroused by the strange 
frequency with which this larva occurred, for it seemed improbable that the 
mosquito of the second commonest larva of Lagos should have remained 
unrecognised by previous observers, and should have continued since 1907 to be 
represented by a few males collected in Ashanti. As the insect evidently 
belonged to the genus Culiciomyia, from which it has been separated on account 
of the peculiar scales on the male palpi, I determined to examine the types of 
that genus at the British Museum when I reached London. 
On doing so I found that the scales on the male palpi of Pect/nopalpus were not 
peculiar to that genus. A detailed examination of the male genitalia of both 
genera would be desirable, but in its absence it seems to me that Pectinopalpus 
fuscus, Theo., is likely to prove a synonym of Culiciomyia freetownensis, Theo. 
This larva showed monthly variation in numbers and appeared to be commoner 
at Lagos than at Ebute Metta. 
Culex duttoni, Theo. 
The larva of this mosquito occurred in an average of 8:3 per cent. of the total 
receptacles examined. Its distribution is apparently greatly influenced by 
environment. As shown in the tables, it is rare in Lagos, but at Ebute 
Metta it is the commonest larva with an average of 78°4 per cent. Seeking 
an explanation of this difference in distribution, an analysis was made of three 
samples of water received from Lagos receptacles which did not contain this 
larva, and of the three samples from Ebute Metta water-receptacles in which 
the larva had been found, with the results shown below :— 
LAGos. Epute Mera. 
1. Chlorine... 2°4 parts per 100,000 | 1. Chlorine ... 1-4 parts per 100,000 
is son) HE 53 53 2; 5s eae py lc 
Sowa: +: 16D abe 
” ” 
F Sat # erhss 
” ” 
Apparently then this species prefers water containing only a small amount of 
chlorine, and is sensitive to any great variation in its amount. It also shows a 
seasonal variation in numbers. 
During the progress of this investigation three native patients suffering from 
Calabar swelling were sent to the laboratory for the purposes of diagnosis. 
Filaria diurna was readily found in the peripheral blood, and all three natives 
lived on the mainland (two at Ebute Metta and one at Agage, an adjacent 
