1913. J 



M. Bbzzi : Indian Trypaneids {Fruit-Flies). 



55 



For the distinction of the numerous genera and species of the Trypaneids^ the 

 following are the principal characters employed : — 



Head. — The general form is important, as the head can be broad or narrow, 

 widened below or not, with the face retreating inferiorly or not. The eyes can be 

 rounded or narrowed ; the epistome prominent or not ; the cheeks broad or narrow ; 

 the occiput swollen inferiorly or not. The antennae are important chiefly on 

 account of their form and of the length of the third joint ; the arista can be bare, 

 pubescent, pilose or plumose on both sides or only on the upper side. 



The proboscis is short, but in some forms is elongated, with the flaps very much 

 prolonged and directed hindwards, and therefore the proboscis appears to be 

 geniculate. 



Very important are the bristles, on account of their position, number and 

 form. These are (fig. i) : — 



Fig. I. — Front view of the head of a Trypaneid, showing typical chaetotaxy. For explanation of 

 the numbers see text. 



1. Vertical bristles (vt.) : on the vertex, two pairs, the inner very long, the outer 

 shorter. 



2. Postvertical bristles (pvt.): on the vertex behind the ocellar spot, only a 

 pair, short and weak, parallel or diverging, rarely wanting. 



3. Ocellar bristles (oc.) : a pair on the ocellar dot, strong, weak or absent. 



