14. LEPTOGASTER 751 



fully flevelopcd and the fourth posterior and anal cells closed. The 

 metamorphoses are only imperfectly known, but the larva of L. cylindrica 

 has been found in field earth. 



The flies usually occur in dry meadows, where they rest on grass 

 stems. They are slow and laborious flyers. 



Sj/nnnymy. — Leptogaster was established by Meigen in ] 803 upon quite adequate 

 characters ; Gonypes of Latreille appeared a year later in Nouv. Diet. d'Hist. Nat., 

 xxiv., 191. 



Tahlc of Species. 



1 (2) Hind femora with longitudinal dark stripes. Abdomen with an 



entire dark dorsal stripe. Small cross-vein absent. 



1 cylindrica. 



2 (1) Hind femora with a subapical dark band. Abdomen with incon- 



spicuous pale bands. Small cross-vein almost always present. 



2 giittiventris. 



1. L. cylindrica DeGeer. Abdomen with an entire dark dorsal stripe 

 and with no bands paler than the ground colour. Hind femora with 

 dark stripes ; hind tibite with the apical third black. Upper branch of 

 the fork of the postical vein forming a part of the lower margin of the 

 discal cell, and consequently no small cross-vein present. (Fig. 405.) 



A remarkably slender fly, which is very distinct from all 

 other British species except the next one. 



^ . Face (including the sides of the mouth) densely covered with yellow or pale 

 yellow tomentum ; face-beard yellowish white, small but not so small as in 

 L. guttiventris, composed of about thirty hairs ; frons yellowish grey ; back 

 of the head (especially toAvards the sides and below) ashy greyish yellow, 

 and bearing a little yellowish pubescence on the lower third, while higher up 

 a postocular row of stout brownish yellow bristles ( = the festoon) extends on 

 to the interocular depression and almost meets the row on the opposite side, and 

 some shorter thin pale hairs occur between and in front of these bristles on the 

 upper quarter of the eyes. Proboscis shining black ; palpi obvious, black, and 

 bearing four or five tiny whitish bristles. Eyes with the front facets enlarged 

 and green in life, but the small hind and lower facets more bronzy green. 

 Antennae brownish black ; second joint orange or ferruginous, and both the 

 basal joints bearing bristles ; third joint long and narrowly oval with a fairly 

 long point ; style thick but not pubescent, not quite so long as the third joint. 



Thorax brownish ashy grey, though when viewed from behind the back 

 part and the scutellum are lighter ashy grey ; the usual three stripes are darker 

 brown, and the middle one is sometimes split by a paler line ; the side stripes 

 are shortened anteriorly, and all three stripes are pointed posteriorly and end 

 well before the hindmargin ; pra^sutural bristle sometimes black and some- 

 times yellowish. 



Abdomen lanky (but not so much as in L, guttiventris), ashy grey with 

 (when seen from above) a narrow clear darker brown uninterrupted dorsal 

 stripe, or (when seen from behind) with a broader less regular and less defined 

 dorsal stripe ; pubescence inconspicuous, short greyish white, _ most distinct 

 about the sides and especially (being longer) beneath the eighth and the 

 neighboring part of the seventh segments. Belly unicolorous yellowish 

 ashy grey, with a very short soft pale pubescence. Genitalia forming a 

 moderate knob ; lateral lamelke shining black, long, and bearing obvious pale 

 yellow pubescence, each with an indistinct short basal segment and produced 



