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these species, especially those of the Sabelini, possess dorsally on 
the apex of the sipho some highly developed crooked bristles, upon 
which they rest when lying on the bottom; similar bristles may 
also be found on the dorsal side of the seventh segment. The 
number and direction of the bristles in the swimming-brush of 
the ninth abdominal segment and of those which belong to the 
sipho, are likewise very much different in the various species. Our 
knowledge of the biology of the animals is, howerer, still very 
small so that we are at the present incapable of de- 
monstrating the presumed accordance between struc- 
ture and function of the hair-complexes. 
In Mansonia the lateral comb of the eighth seg- 
ment consists of about 20 teeth placed in a single row; 
the teeth are long and very acute. Fig. 18 shows two 
of them highly enlarged. In the American species BE NES 
the number of teeth is smaller. At the end of the on the eight 
row of teeth we find a. tuft of 3—4 hairs and, at the g 
base of the sipho, four tufts each consisting of 3—4 ocular. 
rather conspicuous hairs. 
The anal segment (fig. 19) is much longer than broad, at the 
base provided with a band of chitin and furnished with a chitin 
plate which completely surrounds the segment. Laterally the plate 
has a tuft of 5 bristles, and along the edges it bears two small tufts 
each consisting of two bristles. 
The ventral brush is large, but there are no small tufts of 
hairs in front of it. Dorsal tufts divided into four. The whole 
organ differs but at little from that of other Culicid-larvæ (fig. 20), 
and is most in accordance with that of M. perturbans. The system 
of transverse stripes of chitin supporting the tufts (fig. 21) is very 
Similar to that of other Culicid-larvæ. 
One of the most peculiar features in the structure of the Man- 
Sonia larva is the high development of the swimming-brush on 
the Øth segment; this brush is here, in the almost sedentary larva, 
larger than in many of the free-swimming Culex-larvæ. Most 
observers would be inclined to think that it were a powerful organ 
of locomotion; this is far from being the case; even the strongest 
use of the organ is unable to bring the larva to the surface; it 
