54 



EREMOCH.ETA 



The following contrasts may be noted between the more typical 

 Stratiomyidce and Leiitidm. 



Stratiomyid.e 



(excl. Berime and Xylomijince) 



a Third joint of the antennae fiagelliforni 



and distinctly annulated. 

 b 8cutellum often armed. 

 c Abdomen rounded or oblong. 

 d Pubescence soft. 

 e Tibiae without apical spurs. 



/ I'riulurca starting opposite tlie base of 



the discal cell. 

 [I Discal cell almost always pentagonal. 

 It Costal vein ending before the wing-tip 



at the end of the cubital vein. 



/ Cubital fork (if any) short, and with 

 its lower branch ending long before 

 the wing-tip. 

 k Wing-membrane almost always ribbed 

 or rippled. 



I Thoracal squamae often developed. 



are 



The Beyime possess all the aljove 

 characters except e h and k, and 

 only partially failing in them. 



The Xylomyince fail in h ef g h i 1 



Leptid^ 



(excl. Xi/lophagince and C<X7iom;/ince) 



a Third joint of the antennie simple and 



not annulated. 

 b Scutellum never armed, 

 c Abdomen conical. 

 d Pubescence rather stiff. 

 e Tibi;e on at least the posterior legs 



s^airred. 

 / Pr;efurca starting far before the Ijase 



of tlie discal cell. 

 (f Discal cell hexagonal. 

 h Costal vein continued as a thin amljient 



vein all round the hindmargin of the 



wing. 

 / Cul:)ital fork (absent in Illlarimorpha 



only) long, and with its lower l)rancli 

 • ending after the wing-tip. 

 k \\'ing-membrane smooth. 



I Thoracal s(iuamse absent. 

 The XylophayincH fail in a c d i. 



The CoenoDiyime fail in ((bed. 



The Tabcmidce are the only other family with an annulated third 

 antennal joint, but in the great majority of them the basal part of that 

 third joint is large (fig. 76), and well distinguished from the remainder of the 



joint, which forms an annulated t;one, and that cone 

 seems to indicate a step towards the jointed style 

 which so frequently occurs in the subsequent 

 families. No confusion is likely to occur between 

 the Tdbanidce and the Stratiomyidce, as the large 

 comparatively bare thoracal squanne and the tri- 

 angularly wide open cubital fork (of which the 

 lower branch ends far after the wing-tip) at once 

 distinguish the former, and the venation of the 

 Tahanidre is very distinct in many other respects 

 from that of any of the Stratiomyidw. 



In short, in British species (after excluding the very distinct Tahanidce) 

 an annulated third antennal joint indicates a Stratiomyid or a Xyh2}haf/vs, 

 while spurred tibite indicate a Leptid or a Xylomyia, and Xylomyia may be 

 distinguished from Xylophagus by its closed fourth posterior cell. In 

 European or exotic species other forms occur which are not so easily 

 separated. 



The Stratiomyidce comprise about 1000 described species from all parts 

 of the world, of which rather more than 200 are PaUoarctic, and about 53 



Fig. 70. — Tahinius autumnalis. 

 X 20. 



