and of severed Brachycerous families in Bi-ptera. 293 



This being so the venation, invahiable 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 

 ord^r given below in the left column ; in the right column 

 as I propose to rearrange it. 



Stratiomyidse Asilidse 



Tabanidse Empidse 



Leptidas Dolichopodidse 



Asilidse Phoridse 



Bombyiidas Lonchopteridce 



Therevidae Leptidse 



Scenopinidoe Stratiomyidce 



CyrtidsB Tabanidse 



Empidee Bombylidge 



Dolichopodidse Therevidaj 



Lonchopteridce Scenopinidsc 



Cyrtidse 



The Asilidse 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. 



The Empidse 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 Tachydroniia. 



The Dolichopodidse 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 the mandibles is also a Nematocerous character. 



The Phoridaj follow, not only on account of their Nema- 

 tocerous characters demanding an early place in the 

 Brachycera, but also from a number of characters which 

 suggest an affinity with the Dolichopodidse, and in a less 

 degree with the Empida?. I propose to state these at 

 length at the end of the paper. 



The Lonchopteridse 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 



