192 AN ACCOUNT OF BRITISH FLIES. 
in the @, joints one to twelve, very small, thirteenth very long, four- 
teenth short and conical ; in the 2 the antenne are pilose, the four- 
teenth thicker than the others, pubescent and more acuminate. 
Thorax elevated ; scutellum rather small; metathorax with a longi- 
tudinal furrow. Abdomen composed of eight segments, long, hairy ; 
more hairy and longer in the ¢ than in the 2. Wings often pubes- 
cent; hairy along the hind border, mediastinal ending at beyond 
half the length of the wing ; subcostal ending at before two-thirds of 
the length ; radial emerging from the preebrachial transverse veinlet, 
ending at beyond three-fourths of the length ; cubital also proceeding 
from the preebrachial transverse veinlet, ending at very little in front 
of the tip, subapical ending at very little behind the tip; subanal 
forming a fork of the prebrachial ; anal complete; subaxillary not 
reaching the border. Posterior margin much excavated. Legs long 
and slender, pubescent, unarmed ; coxze of moderate size, ungues 
very small; in the ¢ the fore tarsi are often pilose, bare always in 
the 2. Plate iv., fig. 6. 
There are as many as nineteen species recorded from Great 
Britain, but five of these seem of somewhat doubtful occurrence, and 
there are four reputed species. 
They may be divided into two groups, (A) those with spotted 
wings, and (AA) those with unspotted wings : 
A. WinGs SPOTTED. 
(a). Thorax with four dark stripes. 
i. Testaceous; ferruginous stripes. ) 
Wings gray, with pale spots and with a 
pale band in the middle. Legs slender, |. Varius, F. 
hairy, tips of the joints dark brown. 
Length, 2 to 24 lin. Common. 
ll, Silver -gray. Wings with a gray ) 
spot near the fore border at three-fourths 
of length and with gray streaks on the 
veins along the hind hone Costal { Naa ae 
veins black. Legs pale testaceous. 
Length, 3 to 4 lin. Common. : 
ili. Hoary. Wings clouded with gray, ) 
nearly limpid along the costa towards 
the base and at the tips; discal trans- | Chorveus, Mg. 
verse veinlet clouded with black. Abdo- >} — fasciatus, Mg., 
men brown, posterior borders of seg- sylvaticus, Mg. 
ments nearly white. Length, 1} to 2 lin. 
Common. y 
