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146 as in habit. These the student should learn to distinguish.

The principal of the mosquito-like blood-suckers are the Midges (Cheironomidæ) and the Sandflies (Phlebotomus). The following are the diagnostic points:—

Mosquitoes have a long suctorial proboscis, and the veins of their wings are fringed with scales.

Midges are very slender and minute, have a short suctorial apparatus, and wings without scales.

Sandflies are small, slender, and very shaggy, have a comparatively short suctorial apparatus, comparatively long legs; narrow, pointed, hairy wings, and long hairy antennæ.

Fig. 34.—Wing of Culex concolor (male), to illustrate terminology.

The medical man should be able not only to recognize mosquitoes but also to determine genera and species. Obviously, it would be impossible to give here minute descriptions of the large number of species that have been described; I must, therefore, refer the reader to the monographs on the subject already mentioned. On the next page is given a synoptical table which will enable the student to identify the main groups or sub-families to which any given mosquito belongs. It has been prepared after a careful consideration of the various classifications proposed. Most authorities separate the Culicidæ into two sub-families, namely (1)