INTRODUCTION. 6 



Frontal bladder-seam semicircular, forming above 

 tbe lunule a distinctly margined upright arch, 

 usually running steeply downwards over middle 

 of face, usually separated and distinctly sepa- 

 rating the cheeks and jowls at the sides. Anal 

 cell generally short and often subequal in length 

 with 2nd basal cell Eumyidje. 



3. First posterior cell always closed. Vena spuria 



present SvEPHiDiE. 



First posterior cell always open. Vena spuria 



absent 4. 



4. Arista terminal Platypezid^e. 



Arista dorsal Pipunculidje'. 



The two latter families were left in the same divisional group 

 by Brauer, but are easily separated by the character given above. 

 It must be confessed that the table of groups is difficult to put 

 to practical use, especially by a beginner. The Eumyid^e, unfor- 

 tunately given a family termination, is a combination of the 

 Conopid;e, CEstrid.e, and Mttscid.e, all of which are regarded in 

 the present volume as good and separate families. 



The Pupipara, it is understood, consist of three distinct 

 families, Hippoboscid^e, Nycteribiidje, and Streblid^e. 



The superfamilies herein admitted are those recognised by 

 Verrall in his second published volume on British Diptera, and 

 the following table of them is wholly drawn from that work : — 



Table of Superfamilies. 



1. Three equally well-developed pad-like pulvilli. 



Species absolutely eremochaetous (i. e., strong 

 bristles on head and thorax entirely absent) .... Eremochjeta. 

 Two pad-like pulvilli only, the empodium being 

 sometimes absent or sometimes represented by a 

 bristly hair. Species not truly eremochaetous . . 2. 



2. Basal cells long, the anal cell being open or long 



and pointed, because the branches of the 5th vein 

 only gradually diverge, and the upper branch is 

 usually connected with the discal cell by the 

 posterior cross-vein, though sometimes (Bomby- 

 EiiDiE, ScENOPiNiDiE, etc.) it forms a part of the 

 lower margin of the discal cell : wing-venation 

 usually elaborate. Cephalic bristles on frons and 

 vertex not strongly developed, though sometimes 

 visible in AsiLiDiE. Often large or very large 

 species and seldom small, and when small 

 usually with long pubescence among the stronger 



bristles 3. 



Anal cell short except in a few EMPiDiE (Hybo- 

 tin^e) and shorter than the preceding basal cell 

 (when that is present), and the upper basal cell 

 rather long in the Empidje only ; 5th vein 

 with its lower branch recurrent (except in the 

 HYBOTiNiE) and its upper branch quickly lost 



b2 



