910- CHARLES PauL ALEXANDER 
The genus Gnophomyia includes about twenty-eight species of medium- 
sized to comparatively large flies, mostly from tropical America. The 
immature stages so far as known are spent beneath the decaying bark 
of deciduous trees (Liriodendron, Populus, Acer, and others). 
Gnophomyia tristissima O. 8. 
1859 Gnophomyia tristissima O.S. Proc. Acad. Nat. Sci. Phila., p. 224, pl. 4, fig. 18. 
Gnophomyia tristissima is a rather small blackish fly, with dark wings 
and the knobs of the halteres bright yellow. The venation is as shown 
in Plate XX XVII, 100. | 
A second species of the genus, Gnophomyia luctuosa O. S. (Proce. 
Acad. Nat. Sci. Phila., p. 224, 1859), has recently been taken near Wash- 
ington, D. C., by Mr. Shannon. It is a southern species, with a wide 
range over Central America and northern South America. It may be 
readily distinguished from G. tristissima by its stouter build, entirely 
black halteres, and apically pubescent wings. 
Genus Trimicra Osten Sacken 
1861 Trimicra O. 8. Proc. Acad. Nat. Sci. Phila., p. 290. 
The genus Trimicra includes about fourteen described species of rather 
inconspicuously colored flies of medium size. The species are found 
in all the principal regions of the globe, including many of the oceanic 
islands. The genotype, Trimicra anomala, was later considered by its 
describer as being the same as the European 7’. pilipes Fabr., but the 
two should be regarded as being distinct species until the question can 
be settled by the study of ample material. The immature stages are 
spent in moist earth. 
Trimicra anomala O. 8. 
1861 Trimicra anomala O.S. Proc. Acad. Nat. Sci. Phila., p. 290. 
Trimicra anomala is a brownish gray fly. The prescutum has three 
dark brown stripes, and the abdominal segments are margined laterally 
and caudally with paler. The wings (Plate XX XVII, 99) are suffused 
with pale brown, the cross-veins being a little darker. The legs and the 
body are clothed with long, erect hairs. The species is more numerous 
southward and westward. 
