138 Proceedings of the Biologicrd Society of Washington. 
7. Fifth joint of hind tarsus spinose ventrally.8 
Fifth joint of hind tarsus nnspined..10 
8. Kiioh of lialteres black, stalk yellow; abdomen white; legs blacky 
the basal join! of tarsi white . albiventris Loew. 
Knob of lialteres yellow or white.9 
9. Eyes widely separated; legs wliitish, blackened on apical half of 
femora, apices of hind tibiae, and apices of all tarsal joints 
elegans Coquillett. 
Eyes almost contiguous; legs black, j'ellow on apices of coxae, tro¬ 
chanters, and bases of femora; basal 4 joints of tarsi whitish 
smithi Coquillett. 
10. Mesonotum opaque, fuscous. opaca Loew. 
Mesonotum glossy black. 1 ] 
11. Mesonotum with 2 whitish, pruinose vittae . . . hivittata Coquillett. 
Mesonotum unstriped.]2 
12. Abdomen yellow on basal half; legs chiefly yellow; apex of first vein 
not before middle of third vein.. . flavonigra Coquillett. 
Abdomen wholly black; legs chiefly black; apex of first vein dis¬ 
tinctly before middle of third vein. gibber Coquillett. 
It will be necessary to use this table with a certain degree of caution, 
particularly in the character of the presence or absence of spines on the 
ventral surface of the last tarsal joint. I have found it to be a rule that 
where the female has no ventral spines on this joint they are absent in 
the male also; but the presence of spines on the last joint of the female 
tarsus is not an infallible indication of their presence in the male. 
Probezzia pallida n. sp. 
Female.—IVhitish yellow; apical half of antennae brownish; disc of 
postnotum slightly infuscated; last tarsal joint of all legs and tarsal claws 
black; inner side of hind tibiae at apices with a black comb. Wings 
clear, veins yellow. Flalteres jjale yellow. Hairs on body and legs 
whitish. 
Eyes narrowly separated; basal joint of antennae small, globose; joints 
of flagellum elongated, the apical five noticeably longer than the others, 
the entire length of antenna one and a half times that of head and thorax 
combined, antennal hairs short; proboscis shorter than height of head. 
Mesonotum with sparse short setulose hairs arranged seriallj^ on the 
spaces between the areas generally occupied by the thoracic vittfe in other 
Chirohomidee; scutellum with scattered setulose hairs, which are not 
confined to the margin. Abdomen slender, its length slightly exceeding 
that of head and thorax combined; surface almost devoid of hairs. Legs 
slender ; femora and tibiae with weak hairs, those on the hind tibiae 
strongest; basal joint of hind tarsus as long as the next four together, 
exclusive of the claws, fourth joint very short, fifth as long as 3 -f 4, its 
ventral surface with two rows of rather long spines; tarsal claws about 
equal in length to fifth joint, subequal on all legs, each with a long sub- 
