334 
The Ohio Naturalist. 
[Vol. XIV, No. 8, 
Microdon coarctatus Loew. A small bright green species 
with many of the wing veins margined with dark brown. Three 
specimens from Louisiana. 
Microdon flavitibia Walker. Thorax and abdomen purplish 
black. Wings fumose. Of the same form and size as bidens. Six 
specimens from Bartica, British Guiana. 
Microdon rufiventris Rondani. Face, front and thorax 
shining green clothed with golden pile; antennae brown; abdomen 
reddish yellow with the exception of a triangular green spot near 
the scutellum. Legs pale, wings nearly hyaline. Length 11 
mm. One specimen from Bartica, British Guiana. 
Mixogaster Macquart. 
Five American species have been described in this genus. 
Some of them might well be placed in Microdon were it not for 
the discinctly elavate abdomen but others do not show such close 
relationship with that genus. M. breviventris Kahl is the only 
species that has been taken as far north as the United States. 
An additional species was taken at Los Amates, Guatemala, and is 
here described as new. The following key for the separation of 
the known species has been compiled in large measure from 
descriptions and figures that have appeared in various publications. 
1 . Thorax with a middorsal yellow stripe, conopsoides Macq. 
Thorax not with a middorsal yellow stripe. 2 . 
2 . The third longitudinal vein emits a stump into the first posterior 
cell. 3 . 
The third longitudinal vein does not emit a stump into the first 
posterior cell. 4 . 
3 . Wing clear hyaline, legs brown, claripennis n. sp. 
Base of marginal cell and a cloud along the third vein brown, 
bases of all the tibiae light yellow, bellula Will. 
4 . The vein closing the distal end of the first posterior cell almost 
straight, breviventris Kahl. 
The vein closing the distal end of the first posterior cell distinctly 
angulated. 5 . 
5 . Face extraordinarily arcuate, dimidiata G. Tos. 
Face normal, mexicana Macq. 
Mixogaster claripennis n. sp. Length about 10 mm., body 
black with yellow bands, legs generally brownish. Face yellow 
on each side and black at middle, clothed with yellow appressed 
hairs, cheeks black; front largely shining black narrowed near 
lower third where there is a transverse space clothed with short 
yellow hairs, vertex tumid, also a prominence just above base 
of antennae. Antennae long, first segment long and slender, 
second segment short, third segment thickened and about as long 
as the first, whole antenna black except the extreme base of first 
segment which is yellow. Thorax black in ground color, humerus 
with a very small pale spot, suture with a very narrow band of 
yellow pile. Scutellum golden pilose. Wings clear hyaline. 
