230 Orthorrhapha brachycera. 



on the tlbiæ. There are two claws, two pulvilli and a linear em- 

 podium with bristles at the margin. The wings have the mediastinal 

 vein not reaching the margin, (in raptoria the mediastinal vein is 

 wanting, or at all events so weak, that it is practically wanting); the 

 cubital vein is forked, and thus there are two cubital cells; the discai 

 vein likewise forked, thus four posterior cells. — For the rest the 

 wings fall, with regard to venation, into two categories, answering to 

 the two groups of species in the genus, which for the rest each ought 

 to be a separate genus. In the first group [precatoria, stigmatica, 

 melanocephala) {Hemerodroinia s. str.) the subcostal vein is long, and 

 the radial and cubital veins issue near the middle of the wing; a 

 discai cell is present sending two veins to the margin, the upper is 

 branched, the lower is the upper branch of the postical vein, closing 

 the discai cell below; an anal cell is present, and the anal vein is 

 a little recurrent; the first basal cell is a little longer than the second, 

 the anal cell much shorter; stigma is present. In the second group 

 {raptoria, oratoria) {Microdromia Big.) the subcostal vein is short, 

 the radial and cubital veins issue near the base; there is no discai 

 cell and generally no anal cell, the lower branch of the postical vein 

 wanting or only indicated, and the anal vein generally wanting; the 

 second basal cell is much longer than the first; stigma absent. — 

 The axillary lobe is very small. Alula not developed, the margin 

 here fringed. Alar squamula is narrow, long fringed at the margin. 



The developmental stages of H. precatoria have been described and 

 figured quite recently by Brocher (Ann. de Biologie lacustre, IV, 1909, 

 44, fig. 1 — 2). The larva lives in the mud in streamlets. It has a 

 length of 6 mm. ; the body is spindle-shaped, but most attenuated 

 towards the head, more obtuse at the posterior end and here pro- 

 vided with a pencil of six to seven hairs. The abdominal segments 

 have small, transverse swellings below. The tracheal system is de- 

 scribed as closed, and the two large lateral tracheal trunks terminate 

 at each end of the body with „un bouquet de fines trachées", the 

 larva may thus be termed amphipneustic. The pupa resembles chiefly 

 other Empid pupæ, but it seems only to have girdles of small spines 

 but no long bristles above on the abdominal segments. The eight 

 pairs of spiracles are continued out into long threads, which are sup- 

 posed to be tracheal gills. Thus both larva and pupa are evidently 

 adapted to live in water, According to the observation of Brocher 

 of a larva in the aquarium it seems to attach itself a little above 

 the water before pupation. 



The species of Hemerodromia occur in, or in the neighbourhood 

 of woods, generally in the vicinity of water, at the border of lakes 



