148 AN ACCOUNT OF BRITISH FLIES. 
Genus AZycetobia, Mg. 
Body rather short. Head round, flatabove. Eyes reniform. Pro- 
boscis and palpi short ; the latter is 4-jointed, first joint small, second 
long, third small and fourth long. Antenne 17-jointed, end joint 
very small. Abdomen composed of seven segments. Legs stout; tibize 
without spines, very short spurs. Wings broad, small hairs ; brachial 
and cubital (third) forming a sessile fork ; fourth longitudinal vein 
forked near the tip of the wing, and emerging from the pobrachial 
transverse veinlet; fifth forked, forming the pre- and pobrachials ; 
sixth and seventh incomplete. Areolets thirteen, viz., the humeral, 
radical, sub-costal, radial, prebrachial united to the pobrachial, cubital, 
sub-apical, anal, sub-anal, sub-axillary, axillary and three externo- 
medials. 
FIG. 32.—Mycetobia pallipes. a=posterior tibia and spurs ; b=last tarsal joint 
and ungues ; c=wing; d=palpus. 
The larvze feed on fungi and rotten wood. Macquart reared them 
from larvze found in the detritus of elm wood. The only species of 
this genus inhabits woods, and may be taken at rest on tree stems, 
especially decayed ones, and those covered by lichens. 
M. pallipes, Mg. 
Black. Abdomen brown. Head and antenne black; palpi 
yellow. Legs yellowish, tarsi brown. Wings limpid, black veins. 
Spurs yellow. Inhabits decayed tree trunks. 
Mycetobia, Mg. 
GENUS Ditomyia, Wtz. = ' 
Symmerus, Wik. 
Body slender. Head roundish, small. Proboscis and palpi short ; 
first joint small, oval; second long, third and fourth small. Antennz 
17-jointed, slender, compressed ; first joint cyathiform; second 
transverse, the rest ovate-cylindrical ; the seventeenth small. Eyes 
roundish ; ocelli three, central one small. Thorax oval. Abdomen 
seven segments, long, compressed, widened at the tip in the ?, 
linear in the. Legs long ; posterior tibiz longer than tarsi; tibize 
armed by short spines and fairly long spurs. Wings hairy, fairly 
