IXTRODUCXION'. 6 



Frontal bladder-seam semicircular, formiuf^ above 

 tlie luniile a distinctly margined upright arch, 

 usually running steeply downwards over middle 

 of face, usually separated and distinctly sepa- 

 rating the clieeks and jowls at the sides. yVual 

 cell generally short and often subequal in length 



with 2nd basal cell EuMYiD^. 



■3. First posterior cell always closed. Tena spuria 



present Syrphid^^. 



First posterior cell always open. Vena spuria 



absent 4. 



4. Arista terminal Platypezid^. 



Arista dorsal Pipunculid^. 



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 EuMYiDiE, unfor- 

 tunately given a family termination, is a combination of the 

 ■CONOPID.T5, ffisTRiD.T;, and Muscid.e, all of which are regarded in 

 the present volume as good and sepai-ate families. 



The PuPiPARA, it is understood, consist of three distinct 

 families, Hippoboscid^, Nycteribiid.^, and SiREBLiDyE. 



The superfamilies herein admitted are those recognised by 

 Verrall in his second published volume on British Diptera, and 

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



Table of Sajper families. 



Three equally well-developed pad-like pulvilli. 



Species absolutely eremochfetous (/. e., strong 



bristles on head and thorax entirely absent) .... Ehemoch^ta. 

 Two pad-like pulvilli only, the empodium being 



sometimes absent or sometimes represented by a 



bristly hair. Species not truly eremochiutous . . 2. 

 Bas.al cells long, the anal cell being open or long 



and pointed, because the branches of the 5th veiu 



only gradually diverge, and the upper branch is 



usually connected wath the discal cell by the 



posterior cross-vein, though sometimes (Bomby- 



LiiDiE, ScENOPiNiD^E, etc.) it foHus 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 Asilidje. 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 Empid.e (Hybo- 



tin-e) and shorter than the preceding basal cell 



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



rather long in the Empid.e only ; 5th vein 



with its lower branch recurrent (except in the 



Hybotin^) and its upper branch quickly lost 



b2 



