926 CHARLES PauL ALEXANDER 
4. Coloration grayish brown, the prescutum with three dark brown stripes; abdomen dark 
brown with paler caudal margins to the segments; wings very pale brown, the radial 
sector very short, arcuated, angulated, or spurred. [Proc. Acad. Nat. Sci. Phila., 
p. 548-544, pl. 28, fig. 57. 1916.) (Plate XLI, 173.)................ R. cayuga Alex. 
Coloration reddish brown, the prescutum with three indistinct stripes; abdomen yellowish 
brown, the hypopygium bright yellow; wings nearly hyaline, the radial sector somewhat 
elongated, slightly arcuated. [Proc. Acad. Nat. Sci. Phila., p. 544-545, pl. 28, fig. 58. 
19163) 22 (Plate Xe Pwh7.2)) ee eee ee ee denne cn R. rubescens Alex. 
SUBFAMILY Cylindrotominae 
The genera of the subfamily Cylindrotominae may be separated in 
accordance with the following key: | 
1. Head and intervals of the prescutum with numerous deep punctures. 
Triogma Schin. (p. 926) 
Head and intervals of the prescutum smooth........................ Naha al ot OPS 2 
2. Three branches of the radius reaching the wing margin. 
Phalacrocera Schin. (species neorena Alex.) (p. 927) 
Two branches of the radius reaching the wing margin, caused by an apparent fusion 
of Iie DA Brine [ol Silaliel eller tone teilen.e (cleo) she astertclielle fie, ebeiiotlovte\edloige} obleifie dies \elye) is\euesl oh olsertsh( RoR MeN nl aetna a an 3 
3. Three branches of the media reaching the wing margin... .Cylindrotoma Macq. (p. 927) 
Two branches of the media reaching the wing margin..........................2.--. 4 
4. Cross-vein r-m present; cross-vein m obliterated by the fusion of M; on Mi+2; antennae 
of male tipuline in structure....... Phalacrocera Schin. (species tipulina O. 8.) (p. 927) 
Cross-vein r-m usually obliterated by the fusion of Rs+s on M:+2; cross-vein m present; 
antennae of male subpectinate, the individual flagellar segments almost cordate. 
Liogma O. 8. (p. 927) 
Genus Triogma Schiner 
1863 Triogma Schin. Wien. Ent. Monatschr., vol. 7, p. 223. 
There are but two known species of Triogma, one occurring in Europe 
and the other in northeastern North America. The larval life of the 
European species, the only one that is known, is spent on aquatic mosses 
growing in mountain torrents. The insects closely resemble the species 
of Liogma in all their stages. 
Triogma exculpta O. 8. 
1865 Triogma exculpta O. 8. Proc. Ent. Soc. Phila., vol. 4, p. 239. 
Triogma exculpta is a rather small, dull brown fly, with the wings suffused 
with brown. The head and the sides of the thorax are deeply punctured. 
The fly is rare and is insufficiently known. The venation is very much 
like that in the genus Liogma. (Johnson, 1909: 131.) 
