1937] 
Exotic Syrphid Flies 
25 
ened. First posterior cell with an adventitious vein, the 
subapical cross vein is straight. 
Genotype: Microdon beebei Curran. 
I have seen a number of species which fit with tolerable 
accuracy and certainty into the concept above ; among them 
may be mentioned Microdon nigrispinosis Shannon, illucens 
Bezzi and probably bellula Williston. 
Ceriomicrodon n. gen. 
Head in profile not very long but extremely wide, prac- 
tically twice as wide as thorax between the humeri. Occiput 
and vertex moderately developed, in nowise conspicuous. 
Front and face of average width. In profile the face bulges 
out below, much as in Rhopalosyrphus Gig.-Tos. Antennae 
quite elongate, the third joint quite wide and flat and about 
two and one-half times as long as the first joint. Eyes bare 
on either side opposite antennae with a curious narrow 
crease margined with grossly enlarged facets. This may be 
an abnormality, but as it is perfectly symmetrical on both 
sides, it may be normal. Occipital fringe reduced to a single 
row of long collar like hairs, much as in Asarcina or Baccha. 
Abdomen extremely petiolate, the first segment small, ap- 
parently completely fused with second segment, at any rate 
the first and second segments together are nearly ten times 
as long as wide in the middle. The second segment expands 
on its extreme posterior edge rather suddenly to some three 
or four times its narrowest width. Remaining segments 
fused into an oval bulging club. Scutellum quite short, 
broad and rounded, without spurs. Wings with a spur de- 
scending into the first posterior cell. Angles of the first 
and second posterior cells broadly rounded, without a trace 
of spurs. 
Genotype : Ceriomicrodon petiolatus n. sp. 
Cerioimicrodon petiolatus n. sp. 
Face pale yellow, a wide median stripe, the cheeks, front, 
vertex, dorsum of thorax and scutellum fully shining bluish 
black. Abdomen obscurely shining black, second segment 
sub-translucent yellowish brown. Pile of thorax and dor- 
sum microscopically short, save for white flecky pile on 
