phorim;. 237 



oped; coxae stout; femora large, the hind pair sometimes 

 enlarged or flattened; tibiae generally with a few strong 

 bristles. Wings usually large, sometimes very small or 

 entirely absent; with two heavy veins anteriorly which 

 reach only half way to the apex of the wing, and three 

 or four much lighter ones, which run obliquely across the 

 discal portion of, the wing. 



Flies belonging to this family can always be recog- 

 nized by the peculiar antennae and wing venation. They 

 are most frequently to be found about decaying vegeta- 

 ble matter, fallen leaves, dead insects, on windows, or in 

 ant nests. Some have been observed to frequent corpses. 



The larvae are cylindrical and tapering in front. The 

 pupa is oval, distinctly segmented, and bears two slen- 

 der projections from the fourth segment which form the 

 breathing organs. These are connected with the pro- 

 thorax. 



Their habits are extremely diverse. A number of spe- 

 cies have been bred from decaying vegetables, fungi and 

 other decomposing plant matter, while others feed on 

 decaying caterpillars or other insects, as well as snails 

 or other animals. A number live in ant nests, one (Apo- 

 cephalus) as a parasite, and another {Metopina) as a com- 

 mensal. In the case of the former the larva lives within 

 the head of the adult ant, which finally drops off; while 

 the larva of Metopina pachycondylce lives curled about the 

 neck of its host ant-larva, partaking of the food given 

 the latter by the attendant worker ants. Still others live 

 in the nests of certain burrowing bees and wasps, and one 

 is known to be parasitic on spider eggs. 



TABLE OF GENERA. 



1. Wings fully developed 2 



Wings absent, or much reduced in size and venation. . . 12 



2. Third longitudinal vein forked near the tip. ... 3 

 Third longitudinal vein simple, at most thickened at tip. . 5 



23 



