mid of several Brachycerous families in Diptera. 293 



This being so the venation, invakiable as a generic 

 character, must be a secondary consideration in grouping 

 the families, for which characters derived from the mouth 

 parts are of greater importance. It follows that drastic 

 alterations are necessary not only in the group under 

 discussion, but even in the Cyclorrapha. 



The families of the Brachycerous Orthorrapha are ar- 

 ranged in Mr. G. H. Verrali's list of British Diptera in the 

 order given below in the left column ; in the right column 

 as I propose to rearrange it. 



Stratiomyidse Asilidse 



Tabanida3 Empidse 



Leptidffi Dolichopodida3 



Asilidse Phoridoe 



Bombylida? Lonchopterida3 



Tlierevida3 Leptidce 



Scenopinidre Stratiomyidoe 



CyrtidsB Tabanid* 



Empidse Bombylidffi 



Dolichopodida3 Therevidse 



Lonchopteridse Scenopinida3 



Cyrtidffi 



The Asilida3 are placed first on account of the Nema- 

 tocerous hypopharynx and of the process in the pharynx 

 homologous with the " pharyngeal pump " in the Culicida', 

 and therefore also a Nematocerous character. 



Tlie Empidffi follow, as they have the same organ but 

 in a modified form. It is well seen in E. livida, L. and in 

 many of the minute Tachydromia. 



The Dolichopodidai must come next as the possession 

 of a similar process shows a very close connection between 

 these three families, while the arrangement of the mouth 

 as regards tlie mandibles is also a Nematocerous character. 



Tiie Phorida> follow, not only on account of their Nema- 

 tocerous characters demanding an early place in the 

 Bracliycera, but also from a number of characters which 

 suggest an affinity with the Dolichopodidie, and in a less 

 degree with the Empida3. I propose to state these at 

 length at the end of the paper. 



the Lonchopterida! are placed next on account of 

 similarities in the trophi and many other points, follow- 

 ing Dr. Williston's and the late Baron von Osten-Sacken's 



