246 LEPTID^ 



Legs long and thin, almost without pubescence ; front coxie notably long, thin, 

 and pubescent ; front tibise with one rather long spur ; posterior tibi» each with 

 two rather long spurs ; empodium forming a middle pulvillus which is larger and 

 broader than the other two ; claws small. 



Wings (fig. 179) long and narrow, rather clouded or apparently spotted ; prsefurca 

 beginning very considerably before the discal cell ; radial vein ending in the costa 

 near the subcostal vein • cubital vein originating from the prgefurca almost opposite 

 the base of the discal cell, and ending in a long conspicuous fork of which the lower 

 branch ends almost in the wing-tip while the shorter upper branch ends about half- 

 way between the wing-tip and the radial vein ; discal cell emitting three simple 

 veinlets to the wingmargin, and the fourth posterior cell wide open though slightly 

 narrowed towards the wingmargin ; small cross-vein sometimes distinct but often 

 reduced to a point at the place where the upper branch of the postical vein touches 

 the discal cell ; anal cell closed or almost closed at the wingmargin ; fork of the 

 lostical vein rather short because all the basal cells are unusually long and the 

 ower branch of the postical vein is short and steep • ambient vein present, though 

 "aint after the lower branch of the cubital fork. Alula absent. Wing-membrane 

 minutely pubescent all over, but not rippled or ribbed. Alar squamae moderately 

 developed and with a short pale marginal fringe which is composed of several rows 

 of hairs. Halteres rather large and with long stems. 



The larvae live under the bark of rotten trees such as Birch (Betida), Alder 

 (Alnus), and Fir (Pinus), where they are said to be predaceous upon other larvae 

 such as Pyrochroa coccinea, etc. Dr Sharp states however that they only act as 

 scavengers and refuse to eat anything except freshly dead larvae, and he further 

 says that they will not touch rotten larvae but are always on the lookout to suck 

 the juices of (not to eat) any larva which has just died. They are amphipneustic 

 and show relationship to the Leptmce, and the pupa throws off the larva-skin. 



The flies are uncommon, but may be found on the stems of those rotten trees 

 which show signs of wood-feeding coleopterous larvae ; they run about actively and 

 apparently imitate some genera of Hymenoptera. 



This genus used to include Xylomyia (Siibida), which it resembles in 

 the annulated third joint of tlie antennae and somewhat in the venation, 

 but Osten Sacken remarked (Berlin. Ent. Zeitschr., xxvi., 364, 1882) that 

 in Xylomyia " the prosternal plate, intervening between the front coxa3 

 " and the anterior thoracic orifice is large ; the front coxae short ; the 

 " abdominal segments but little extensile; in these characters Subula is 

 " like the Beridina. In Xylophagus, on the contrary, the prosternal plate 

 " is small, and hence, the interval between the front coxse and the anterior 

 •' thoracic orifice is" short ; the front coxae are inserted very near the head ; 

 " they are long, cylindrical and very movable ; the abdominal segments 

 " are loosely joined, with extensile connecting membranes; all these 

 " characters are those of the group Tabanidae-Leptidse " (figs. 155, 156). 

 The result of these distinctions is that Xylomyia is now relegated to the 

 Stratiomyida:, while Xylopliagus is considered to belong to an outlying 

 subfamily of the Leptida:,. 



Xylophagus is composed of very few species, and only two have been 

 well recognised from Europe, and even of these two the male of X. cinctus 

 has hitherto been scarcely distinguished. I am however of opinion that 

 closer examination will produce more European species, as I shall 

 have to describe one from Central Europe as new to science. Several 

 species occur in North America, of which some are very closely allied to, 

 oven if not identical with, European species, and one species has been 

 recorded from South America. 



Synonymy. — Xylo/Jidi/us was established by Meigen in 1803 with " Xemotehts 

 " cinctm Deg." given as a representative species, but even in 1804 and 1820 Meigen 

 had not yet seen a specimen of X. cinctus and therefore could not have established 



