SCENOPINUS 597 



for tlie reception of the short thick front femora. Scutellum short, flat on the disc, 

 and quite unarmed ; metanotum fairly large but inconspicuous. 



Abdomen flattened, more or less elongate oblong, and composed of seven or eight 

 segments, while all the middle segments bear across their middle an obvious trans- 

 verse depression, and in the male several of the segments have the foremargins 

 white. Genitalia of the male large. 



Legs short and stout ; front femora especially short and thick ; pubescence and 

 bristles absent except for some spur-like bristly hairs at the tip of the tibiae. 

 Pulvilli two, small. 



Wings with a limited and apparently simple venation ; costal vein extending to 

 the end of the discal vein and then abruptly ceasing so that the ambient vein is 

 absent ; subcostal vein short ; prsefurca rather short ; cubital fork moderately long 

 and rather triangular, with both branches ending in the foremargin of the wing ; 

 discal cross-vein placed just beyond the middle of the discal cell, and consequently 

 the upi^er basal cell nearly twice as long as the lower one ; discal vein apparently con- 

 sisting of a single simple * vein with two cross-veins extending from it to the upper 

 branch of the postical vein and in this way forming the discal cell, and this simple 

 discal vein ends in the wingmargin before (or rarely at) the tip of the wing ; discal 

 cell long and narrow, but gradually widening from base to tip ; postical vein with a 

 long very wide open fork, of which the upper branch forms the whole lower margin of 

 the discal cell, and of which the lower branch curves down rather quickly and joins 

 the anal vein well before the wingmargin, thereby forming a stalked anal cell ; posterior 

 cells three only, the first one being long, narrow, and almost always open ; alulae well 

 developed. Squamae (alar) small, with very short fringes ; thoracal pair hardly 

 developed. Halteres with very large knobs and rather short stems. 



This genus has no ally in the Palsearctic region, and consequently 

 should be easily recognised. The figure, venation, and antennae are each 

 by themselves sufficient to distinguish it. 



Sccnopiivifs contains but few species, of which only two are known to 

 occur in Britain ; from 1845 to 1873 only two other European species 

 were recognised, but since then eight more have been described from the 

 Palccarctic region. The genus is recorded from Europe, Egypt, North 

 America, Surinam, and Hawaii. The flies are usually seen resting 

 quietly on windows, and more especially in stables or outhouses, but I 

 once found some on Asparagus in my garden. Mr Jenkinson once saw 

 some males dancing in the sun and the white markings on the abdomen 

 made them look like beads of silver. 



Tahle of Species. 



1 (2) Legs mainly reddish. 1 fenestralis. 



2 (1) Legs blackish, except on the tarsi. 2 niger. 



1. S. fenestralis Linne. Legs mainly reddish. Frons dull. Eyes of 

 the male touching. 



A rather small oblong dull black fly, which often occurs on 

 windows. 



cJ. Dull black, very densely and coarsely punctate, almost shagreened. Face 

 scarcely existing because the large mouth-opening occupies almost all the 

 space below the antennae, but the narrow bare side-cheeks are dark greyish 

 and slope down into the epistomal depression, which has its upper boundary 

 distinctly above the antennae so that the antennae arise from within it ; 

 the eyes rapidly diverge from the top of the frons down to their lowest 

 part where their interval is about twice as wide as at the antennae ; 

 at the back of the mouth-ojiening is some thin grey pubescence, which extends 

 along the narrow jowls and part way up the shallow back of the head but 



* Vide Corrigenda. 



