BRITISH FLIES 17 



and especially the tarsi, rather long and not stont even 

 thongh strong; front coxse long. Scutellum unarmed, except 

 in Ccsnomyia. Perfect insects (with extremely rare exceptions), 

 not blood-suckers. III. LEPXiD.f:. 



The Leptidoi are rather large to rather small elongate flies, not at 

 all flattened, but with a rather conical abdomen and with lono' wind's. 

 Their colours are usually sombre, but many of the larger species have* 

 extensive orange markings on the alxlomen, while others bear very fugitive 

 golden pile. They may be distinguished from the allied families by the 

 spurred tibia% the practical absence of the thoracal squamai, and (with 

 the exception of the Xylophaghue and Coenomyime) the simple thircl 

 antennal joint ; they also bear a characteristic pubescence, which is of 

 a sparse equal bristly nature, though quite devoid of strong bristles 

 ( = macrochsetse). 



The Xylophagiiuf and Coenomyime have a distinctly 8-annulated 

 flagellum, and are consequently allied to the 

 closing subfamilies of the Straiiomyuke, which 

 also agree with them in having the tibiae more 

 or less spurred; the entire ambient vein dis- 

 tinguishes them Ijut is not a very obvious 

 character, and further details of distinction are 

 given under their descriptions. The arista may *•'''• ^^■-SymphoromyUi 

 sometimes appear to be subdorsal (Symphoro- 



myia) because of the peculiar formation of the third antennal ioint 

 (fig. 38). 



8 (3) Thoracal squamoe conspicuously large. Scutellum never armed. 



9 (10) Head large and conspicuous, semicircular anteriorly, but fittino- 



posteriorly squarely on the front of the thorax, and about as 

 wide as, or wider than, the thorax; antenna with the third 



¥m.Z^.~To.hanusmaculicm"n.is ?. x 3. 



joint annulated, but very rarely tlagelliform {Hexatoma, etc.), 

 and the basal annulation much larger than the others so as to 

 almost reduce the other annulations to a thick jointed style, 

 and nev^er with any approximation to an arista. Thorax and 

 abdomen rather flat and broad, never at all gibbous; genitalia 

 never prominent. Venation normal; cubital fork very wide 

 open ; posterior cells always five ; small cross-vein always 

 present ; ambient vein distinctly entire. Tibite always spurred 



B 



