NouTu Amehican Dipteka. 



TABLE OF FAMILIKS. 



1. Flies of a leatliory or horny structure, living parasitically in 



the adult state upon warin-blootled vertebrates; head small, 

 either closely united to the emarginate anterior part of 

 the thorax, or folding back into a groove upon the dorsum; 

 mouth- parts incomplete, the palpi wanting; legs separated by 

 the broad sternum ; abdomen indistinctly segmentated ; claws 



well developed. 49 



Flies of softer structure, never living parasitically in the adult 

 state upon warm-blooded vertebrates; head separated from 

 thorax by a free neck 2 



2. Antennas many-jointed, often longer than the thorax, the two 



basal joints, only, differentiated, the remaining joints usually 

 distinct; palpi composed of from tliree to five joints, usually 

 elongate ; anal cell never closed or narrowed at the margin* 



(Nema tocera.) 3 



Antennae rarely as long as the thorax, composed primarily of 

 three joints, the third of which may be simple or complex, 

 (that is, composed of more or less distinct annuli or segments,) 

 with or without a terminal or dorsal arista or style; anal cell 

 closed before the border, or distinctly narrowed in the border, 

 ' or, if other structure, the antennae composed of three simple 

 joints; palpi rarely much elongate, composed of from one to 

 three joints 12 



3. Dorsum of thorax with a distinct V-shaped suturet; wings (want- 



ing in Chionea) many-veined, often with a complete discal 

 fell; ocelli wanting (present in Trichocera); often large 



flies Tii'ULiDyE 



Dorsum of thorax without a V-shaped suture, or rarely with any 

 transverse suture (Blepharoceridae.) ... 4 



* P lee ia, nd perhaps some others, may be exceptions. 



tBittacomorpha, Ptychoptera, and Idioplasta will alone 

 cuiisedoii there. They have the suture incompletely V-shaped aud sinu- 

 OUK. The last will be dislinguished from Uhyphida: chiefly by the 

 absence of ocelli ; tlie two former will be separated Irom the C u 1 i c d as by 

 llie absence of hair on the veins, their large size, aud in Bitiacomorplia 

 by the peculiar clubbed tibia;. 



