SUBDIVISIONS OF DIPTERA. CULICTDJE, 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^:, 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. 



792. 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 more than 

 six joints : whilst in all the remainder, the antennae are short, 

 not having more than three apparent joints. In the second, NOTA- 

 CANTHA, the last division of the antennae is really composed of two 

 or more ; the proboscis does not project much from the mouth, and 

 is furnished with only two lancets. In the third, TANYSTOMA, 

 the antennas have only three joints, the last usually terminated 

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

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

 capable of being withdrawn into the mouth. 



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

 families of CULICID^E and TIPULID^E ; the former known as the 



Flo. 623. CULEX PIPIENS, female, natural size and magnified, with head of male, and the larva. 



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 ; but coming to the surface to breathe, whicii 



