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A careful description of the markings on each leg, commencing with those
on the femur and ending with those on the fifth tarsal segment, should be
made. In some species complete bands of white scales encircle the legs near
the joints, and the position of these bands should be noted. In addition
small patches of white scales will be found in some species on certain seg-
ments of the legs ("speckling") and in some species one or more of the
terminal tarsal segments of the hind legs will be found to be white-scaled in
their whole length.
Finally the ungues, sharp-pointed horny structures attached to the tip of
the fifth tarsal segment of each leg, will be examined.
Generic dif-
ferences are
founded upon
scale charac-
ters.
The description being completed we must attempt to classify the mosquito
in its correct genus and species. At present the shape and arrangement
of the scales found on the head, thorax, abdomen and wings of mosquitoes
are the anatomical characters upon which the distinctions between the
different genera in the sub-family Anophelin are based, but there
are many who maintain that a generic grouping founded upon these
characters is not satisfactory, and the matter is not yet settled. The subject
of scale structure, however, is interesting, and, with the saving clause
that the opinions now held by entomologists on the matter are liable to
correction as a result of future work, we may give here a brief sum-
mary of the characters by which the different genera in the sub-family
Anophelin met with in India are distinguished from one another. These
genera are:-
1. Anopheles.
2. Myzomyia.
3. Stethomyia.
4. Pyretophorus.
5. Myzorhynchus.
6. Nyssorhynchus.
7. Cellia.
8. Neocellia.
The shape and arrangement of the scales and hairs on the thorax and
abdomen serve as the primary characters by which these genera are distin-
guished, and our examination must be directed firstly to these regions. So far