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       (2) The "palmate hairs." (Figure 7, C.)

       If the dorsal surface of the abdomen of the larva be examined at about the
third or fourth segment, a pair of prominent small conical or fan-shaped hairs will
be seen. The hairs are arranged in pairs—one pair to each segment of the abdo-
men—and their function is to keep the larva floating in a horizontal position at
the surface of the water. Each palmate hair consists of a stalk, to the free end
of which is attached a conical bundle of about fifteen to eighteen hairs,
arranged round the stalk, like the petals of a flower of which a portion of the
circle is incomplete. At the surface of the water these leaflets spread out and
form a series of little cup-shaped organs which keep the larva afloat.

       Both the number and the shape of the palmate hairs of different species of
larvæ vary considerably, so that in this fact we have a second means of dis-
tinguishing between the larvæ of different species of mosquitoes.

       In some species, for example, the larvæ are provided with a pair of palmate
hairs on the thorax and on all the segments of the abdomen except the last two,
e.g., A. Fluviatilis, A. Culicifacies.

       In other species there are no palmate hairs at all on the thorax and only
rudimentary ones on the first and second abdominal segments, the true palmate
hairs being present from only the third to the seventh segments of the abdomen
(e.g., A. Rossii, A. Stephensii). In other species again, the first three abdo-
minal segments are devoid of true palmate hairs (rudimentary ones may be
present on the third segment), e.g., A. Turkhudi. As regards the shape of the
palmate hairs, considerable differences exist, which are useful points of distinction
between larvæ.

       Thus, in A. Rossii larvæ each leaflet of the palmate hair is provided with a
very long terminal filament (see Fig. 7), in the larva of A. Fluviatilis and
A. Theobaldi, on the contrary, the terminal filament is so short as to form only
short spine.

       A reference to the figures of the different larvæ will show other differences
in the shape of the palmate hairs by which the larvæ can be recognised.

       (3) The Antennœ. (Fig. 7, B.)

       These structures are of course very easily recognised, and in the larvæ of the
majority of Indian species the characters of the antennæ differ but little. A
very small hair (E, Fig. 7) should be noted on the outer side of the antenna
in the majority of Indian species. Two of the Indian species, however (viz.,
A. Nigerrimus and A. Barbirostris), are easily distinguished from all other larvæ
by the fact that their larvæ possess a stout branching hair on the inner side of
the antenna, quite distinct from the small external hair referred to above.

       (4) The pattern on the head.

       Although the pattern on the dorsal surface of the head of anopheles larvæ

E