156 
A Monograph of Culicidae. 
and December; District of Columbia in January, March, May, 
June, July, August, October, November, and December; New 
York in May, July, and August; Virginia in June and October ; 
New Jersey in May ; Texas in May, &c., &c. 
Sub-Species and Varieties. 
A very large number of mosquitoes have been received from 
almost all parts of the world in tropical and sub-tropical climates, 
and from some of the warmer temperate zones, which present a 
certain similarity in general appearance, and which present no 
important structural differences from one another. These all 
centre round the East Indian species which was described by 
Wiedemann as Culex fatigans. A typical specimen of this species 
has been described from this region. 
Even in this region the species is subject to considerable 
minor differences in colour, in size, and in chaetotactic 
characters, whilst some of those from distant localities present 
more marked variability from the type. After examining the 
wings, palpi, genitalia, ungues, the scale structure and the chaetae 
of the scutellum in some hundreds of specimens from different 
parts of the world, I am forced to place them all under Wiede¬ 
mann’s species. In regard to the ungues, $ genitalia, palpi, 
and scale structure, they all agree, but there is considerable 
variation in the relative lengths of the two fork-cells and in the 
number of chaetae in the middle lobe of the scutellum. I hoped 
the latter structure would prove of specific importance, but after 
tabulating numbers of specimens I found that the chaetotactic 
characters of the scutellum failed ; and this was particularly 
emphasised in specimens from certain districts in which I found 
the number of chaetae in the mid lobe now and then augmented 
by a smaller one, either a remnant of a degenerating spine or the 
rudiment of a new one, which, I could not decide. The number 
of chaetae in the mid scutellar lobe varies, I find, from six to 
ten; this latter number occurred only in some specimens from 
New Amsterdam. As instances of the variability in this respect, 
I may quote the following from my notes : — 
St. Vincent . . $ 7 mid scutellar bristles. 
Montserrat 
