LEPTID.E 233 



bristles or spicules but usually Avith some very tiny l^ristles placed in rows down 

 the tibite or beneath the femora, and with all or at least the posterior tibife spurred 

 (hind tibiae only in Lampromyia sericea), there being sometimes one spur on the 

 front tibiae, always two (except as just mentioned) on the middle pair, and one or 

 two on the hind pair (in Hilarimorpha the spurs are stunted) ; front coxse elongate. 

 The legs never exhibit any dilatation (hind tibiae slightly clubbed in Vermileoninw) 

 or structural ornamentation, but very frequently " touch-hairs " exist beneath the 

 front tar.si. Pulvilli three (two in Lampromyia 2)0,llida, and perhaps in Hilari- 

 morpha), the empodium being pad-like. 



Wings in typical Leptidm (tig. 160) with a comparatively simple venation, because 

 the discal and small cross-veins are well developed and no veins anastomose or crowd 

 together anteriorly, while all the veins run out separately to the posterior margin 

 except that sometimes the long anal cell is closed just before the wingmargin ; cubital 

 vein with a long simple usually bell-mouthed fork of which the lower branch usually 

 ends well after the wing-tip, but hardly so in Ptioliivx (fig. 161) and Spania (fig. 209) ; 



Fig. 161. — Ptiolina ohscura $. x 13. 



discal cell long and almost hexagonal and emitting three almost parallel veinlets 

 to the hindinargin, and consequently the five posterior cells are open and 

 simple ; discal cross-vein before the middle of the discal cell (usually well 

 before, but in Spania at the middle); basal cells long and almost equal in 

 length ; ambient vein entire and obvious though sometimes thin all_ round the 

 hindmargin of the wing. The venation however in some of the subfamilies exhibits 

 considerable modification as in Coenomi/ia (fig. 186) the small cross-vein is absent 

 and the upper branch or the postical vein forms for a long distance the under- 

 margin of the discal cell; while in Xylophagus (fig. 182) the cubital fork is 

 comparatively short and its lower branch ends in the wing-tip, and the small cross- 

 vein hardly exists because the upper branch of the postical vein often just touches 

 the undermargin of the discal cell ; and in Rhachiceriis (which may belong to the 

 Xylom)/ince) 'And in Lampromyia (fig. 183) the third veinlet from the discal cell 

 bends sharply downwards and almost or quite closes the fourth posterior cell; in 

 Vermileo (fig. 184) the cubital fork is comparatively short but the lower branch 

 ends far below the wing-tip, and the lower branch of" the discal vein runs parallel 

 and rather close to the upper branch of the postical vein, and it would only require the 

 anastomosis of these two latter veins and the absence of the cross-vein at the base 

 of the third posterior cell, which sometimes even occurs in Vermileo (fig. 185), to 

 produce the remarkable venation of Hilarimorpha (fig. 1 78) which is the only genus 

 of the Leptidm with four posterior cells and no discal cell. Wing-membrane smooth 

 and often glittering, in no way ribbed or rippled but very minutely pubescent. 

 Alula usually but not always well developed. Alar squamae fairly even if not 

 strongly developed, and fringed on the margin with numerous hairs (Leptis, etc.) 

 or with one row of hairs {Chrysopilus, etc.) ; thoracal pair absent, but the frenum 

 distinct and developing a rather broadened membrane near the angle. Halteres 

 conspicuous, rather large and with a rather long stem. 



The Leptidcv are usually easily distinguished from the Stratiomyida: hy 

 their simple non-annulated third antennal joint, by their spurred tibise, 

 and by the prajfurca starting long before the base of the discal cell, but 

 the boundary line between the two families is not easily defined and has 

 been discussed by me at some length in the notes vmder the Straliomyidcv. 

 The only Lc^tidm with an annulated flagelliform third antennal joint are 



