::os 



ual of North American Diptera (1909) and in Verrall's British Flies, 

 volume 5 (1909). 



Tabular Arrangement of Families 

 Tribes* Superfluities Famitiesj 



Platygenya 



Orthogenya 



{ 



Stratiomyioidea 



Tabanoidea 



Cyrtoidea 



Asiloidea 



Therevoidea 



Empididoidea 



{ 

 { 



{ 



Stratiomyiidae 

 Xylophagidae 

 Coenomyiidae 

 Acanthomeridae 



Tabanidae 

 Leptidae 



Cyrtidae 

 Nemestrinidae 



Mydaidae 

 Apioceridae 

 Asilidae 

 Bombyliidae 



Therevidae 

 Scenopinidae 



Empididae 

 Dolichopodidae 



Keys to Families 

 larvae 



1. Posterior spiracles approximated, situated within a terminal or sub- 

 terminal cleft or chamber, usually concealed ; body entirely sha- 

 greened or wholly or in part longitudinally striated 2 



— Posterior spiracles rather widely separated, visible, situated on ap- 

 ical segment, which may be truncated, chitinized, or armed with 



*Tribe in this paper does not have the application given to it in contemporary 

 papers, but has that which Brauer gave it. He used it to designate his subdivisions 

 of the larger divisions of Nematocera and Brachycera. 



tThe sequence of the families in the keys is not in accordance with the above 

 list, the keys being framed to facilitate identification and not to indicate affinities. 



