20 BRITISH FLIES 



12 (1) Two pad-like pulvilli only, the empodium being sometimes absent 



or sometimes represented by a bristly hair (fig. 42). Species 

 not truly eremoch?etous. 



Third joint of the antennte never truly annulated, though indica- 

 tions appear in the blunt antennae of Srenb/miiihe and in the remarkably 

 jointed style or club of Jli/daidce, and while any style or arista is apical 

 or subapical in the earlier* groups, it may become dorsal in some of 

 the MiOKOPHONA. Anal cell almost always closed, 

 long in the earlier* families, but short in the Um- 

 pidce, and obsolete in the subsequent families ; 

 cubital vein almost always with a long fork in the 

 earlier* families, ]jut often simple in the E/iij/uke, 

 and almost always simple in the subsequent 

 families ; fourth posterior cell often closed in the 

 earlier* families; thoracal squamae always un- 

 developed. Species often predaceous in the perfect 

 state, but never blood-suckers. 



Exceptions may occur in the pulvilli being 



obsolete (Leptor/aster, Anthrax., etc.) or (said to be) 



three in number {Cyrtosia). The Scenopinidw 



Fia. ii.—Asihis era- ^'^^ MydaidcB appear to be eremochagtous, l)ut 



'broniformis S- they are curiously l)ald flies, and are undou1)tedly 



related to the Tlierevixht' and Axi/idcp. Some 



Asilidce are apijarently not chjetopliorous, but that is caused by dense 



coarse pubescence being substituted for the normal bristles {Laphria, 



etc.). Some Bonihylidce {Plntyp)ygus., Cyrtosia, etc.) have the cubital 



vein simple. 



13 (24) Basal cells long, the anal cell being open or long and pointed, 



because the branches of the postical fork only gradually 

 diverge, and the upper liranch is usuall}' connected with the 

 discal cell by the small cross-vein, though sometimes 

 {Bomlylidce, Scenopinida', 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 Asilidce. Often large or very large 

 species and seldom small, and when small usually with long 

 pubescence among the stronger bristles. 



14 (17) Aerial species almost always clothed with dense furry pubescence. 



Legs thin and only suitable for alighting, and consequently 

 armed with little more than spicules (not true bristles) on the 

 femora and tibiae. Eyes nearly always touching in the male 

 ( = holoptic), and never bulged out because of a sunken vertex. 



TROMOPTERA. 



Sometimes long strong bristles or bristly hairs occur on the thorax 

 and scutellum, and then the legs bear stronger spicules, and in the 

 Therevidct apical circlets of spines occur on the tilua?. Antenna? with 

 an apical style (if any) whicli sometimes l)reaks up into a pencil of 

 hairs. Proboscis very long, thin, and porrect in many Boinhylidw. 

 Very rarely some species are quite bare of pubescence {(TlaheUuhi, 

 Systropits, etc.) and the exotic Systropimf are very elongate, very thin, 

 quite bare species. 



* The term "earlier " aiipliiis to all t.liose faniilii.'s liefure l.bu EmpiLhe. 



