4 
posterior legs the darker; hind femora with a dense row of short 
hairs below the basal half, these hairs have their apices curved 
backwards and touching each other thus forming a characteristical 
fringe (somewhat similar is found in albipennis Wood); the hind 
tibial bristles distinet though not strong. Wings somewhat dark 
tinged, veins blackish; costa nearly half the wing-length (0,46— 0 , 47 ), 
costal divisions proportionately about as 4—2—1; angle at fork 
not large; costal cilia rather long; fourth vein evenly curved. Hal- 
teres yellow. — Female. Similar to the male and distinguished 
from albipennis by the wings and from pleuralis by the costal 
divisions; hind femora without fringe. Length 1,7—2 mm. 
Bogø south of Sealand and Ry in Jutland l /i — 4 /s in 1917 and 
1918 (the author); a number of males and one female. 
4. A. basispinata n. sp. J'. 
A species related to the foregoing but easily distinguished by 
the armature of the hind femora. 
Male. Frons blackish grey, duil, not mueh broader than long; 
bristles strong, inner bristle of lower row a little below the outer 
and nearer to it than to the upper supraantennal bristle; supra- 
antennals equal or practically so, the upper pair a little less distant 
than the inner bristles of the middle row; the lower supraanten- 
nals only slightly more approximated than the upper. Antennæ 
black, of ordinary size or a little over, arista distinetly pubescent. 
Palpi well developed, yellow, with ordinary bristles. Thorax black 
or greyish black; mesopleura with bristles of which one or two of 
the lowermost are a little longer than the rest. Scutellum with 
two bristles. Abdomen black, distinetly greyish; generally very 
narrow a little lighter hind margins to the segments are visible ; 
the hindmarginal hairs on sixth segment distinet. Hypopygium not 
small, on each side in the middle with an almost vertical row of 
six or seven bristles, directed more or less downwards; ventral 
plate yellowish, large, nearly reaching beyond the hypopygium, 
broadest at the end and here broadly rounded; anal tube of medium 
size, yellow. Legs brownish yellow or a little darker; hind femora 
below at the base with two short rows alongside of somewhat stubby 
bristles, the bristles of the anterior row directed downwards, those 
