STRUCTURE OF THE ADULT MOSQUITO. 
THE HEAD. 
The head is more or less globose, inserted upon a slender, flexible neck, a large 
part of its surface occupied by the eyes; there is a prominent clypeus, the an- 
tenne are long, and the mouthparts consist of a long sucking proboscis and a 
pair of palpi, usually considered maxillary, inserted at its base. There are no 
ocelli, 
THE EYES. 
The many-faceted compound eyes are large, in most species almost or quite 
contiguous above and beneath. In front the eyes are deeply emarginate to 
make place for the insertions of the antennz and the depth of the emarginations 
varies with the size and place of insertion of these organs according to the 
species or the sex. As the basal joint of the antenne is often much larger in the 
male than in the female, in accordance with this the emargination of the eyes 
is deeper in that sex. 
Aside from the emargination the eyes of the two sexes usually differ somewhat 
in shape and those of the female may be somewhat larger than those of the male. 
In the culicine tribe the eyes are markedly broadest at the sides and are much 
narrowed above the antenne, particularly in the male; beneath they are broad 
and may be contiguous in’ their whole width. In the Sabethini the eyes are 
nearly as broad behind the antenne as at the sides and the sexual differences are 
less marked. In certain genera of this tribe the eyes are broadly contiguous be- 
hind the antennz ; in other forms a chitinous wedge is inserted between the eyes 
in such a manner that the eyes touch at their hindermost angles and diverge 
towards the front. In a curious sabethid from the Philippine Islands, Heiz- 
mannia scintillans, the eyes are separated above by a broad strip of chitin, 
almost a third the entire width of the head. In the Culicini the eyes, when 
contiguous above, are never contiguous along the entire margin. The chitin of 
the occipital region is produced wedge-shaped between the eyes ; when this wedge 
is small the eyes are contiguous, when large they are separated, the separation 
being usually greatest at the broadly rounded hind angles. In this tribe the 
median suture of the occiput may be seen continuing forward between the eyes 
thus clearly indicating that the intra-ocular wedge belongs to the occiput. In the 
Sabethini, as already mentioned, a wedge is inserted anteriorly and the eyes are 
approximated at their hind angles. 
In addition to the compound eyes there are present a pair of rudimentary or 
vestigial eyes. These are situated laterally, close to the hind margin of the 
compound eyes. They are covered by the scale vestiture of the cheeks and are 
therefore not visible; however, they become plainly visible in a balsam prep- 
aration in which the pigment of the eyes has not been destroyed. These vestigial 
eyes consist, in fact, wholly of groups of pigment cells; there does not appear to 
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