SUBDIVISIONS OF DIPTERA. CULICID^E, OR GNATS. 197 



amongst the hair or feathers. That which is parasitic on Sheep 

 is known as the Tick. One minute species infests the Hive- Bee; 

 and this is remarkable, not only for being destitute of wings, but 

 of eyes also. In the other family, that of NYCTERIBIID^E, the 

 general form still more nearly approaches that of Spiders. The 

 group contains but a small number of species, all of which are 

 parasitic upon Bats, and are termed Bat-Lice. 



726. The remaining Diptera, constituting by far the larger 

 proportion of the class, may be subdivided into four sections. 

 In the first, NEMOCERA, the antennae are composed of six joints ; 

 whilst in all the remainder, the antennae are short, not having 

 more than three distinct joints. In the second, NOTACANTHA, 

 the last division of the antennas is really composed of two; the 

 proboscis does not project much from the mouth, and is furnished 

 with only two lancets. In the third, TANYSTOMA, the antennae 

 have really only three joints, the last being usually terminated 

 by a seta or bristle. And in the fourth, ATHERICERA, the 

 antennas are only two- or three-jointed, and the proboscis is 

 capable of being withdrawn into the mouth. 



727. Section I. NEMOCERA. To this division belong the two 

 families of CULICHXE and TIPULID.E ; the former known as the 



FIG. 423. CULEX PIPIENS, female, natural size and magnified, with head of male. 



Gnat tribe, the latter as the Harry Long-legs. Both are 

 remarkable for their beautifully-tufted antennae ; but the former 

 are distinguished by the length of the proboscis. Gnats are 

 well known to abound chiefly in damp situations ; the reason 

 being, that their larvae are inhabitants of the water. In this 

 state they are very active, swimming with great agility, and 

 often descending ; bu^ coming to the surface to breathe, which 



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