THE ORDER DIPTERA 45 



= horn, or antenna). Flies which are not, or very seldom, 

 midge-like. The antennze are of diverse form : usually they 

 consist of 3 dissimilar segments, the 3rd of which is often 

 elongate, is sometimes compounded of a series of indistinctly- 

 separated subsegments, and often carries a style or an arista, 

 which is terminal, or subterminal, or, rarely, dorsal. (In 

 certain species of one family {LeptidcB) the antennae consist 

 of a large number of segments, and in that respect resemble 

 the antennse of Nematocera.) The maxillary palps are 

 usually composed of i or 2 segments and are not ilexible. 

 The venation of the wings is often complex ; the 2nd longi- 

 tudinal vein is not forked, but the 3rd often is. 



2. Suborder Cyclorrapha. 



The suborder Cyclorrapha is divided into two sections, 

 as follows : — 



Section i. Cyclorrapha A sch';sa (a privative, and (rx/fa = 

 a cleft), in which the frontal lunule is more or less indefinite, 

 and a frontal suture is not present at all. 



Section 2. Cyclorrapha Schizophora {(Ty[t,a = a cleft, and 

 <l)opew=l wear), in which both the frontal suture and frontal 

 lunule are always well defined. None of the veins of the 

 wings are forked. 



The Cyclorrapha Schizophora again are divided into 

 two subsections, as follows : — 



Subsection i. Muscoidea, of which the common house-fly 

 is a typical example. 



Subsection 2. Pupipara, or " Tick-flies," blood-sucking 

 parasites which live among the hairs of mammals or among 

 the feathers of birds. 



