43 
opposite sexes; in the female the abdomen is black, while in the male 
it is largely or wholly yellow ; in the female the thorax is gray pollinose, 
marked with two black vitta?; in the male it is yellowish pollinose, 
marked with four black vittsej length, 5 to 7 mm. Grimsby, Canada; 
Maine; Franeonia and White Mountains, New Hampshire; District of 
Columbia; North Carolina: Tifton, Ga. ; Texas, Colorado, and California. 
(Dipteres Exotiques, Vol. II, Part III, p. 233(76); 1842. Gymnosoma 
occidua Walker, List Dipt. Insects, Part IV, p. 692; 1819. Gistogaster 
divisa Loew, Diptera Amer. Sept. Indig., Centuria IV, No. 88; 1863. 
Gymnoclytia divisaBr&ner and Bergen stamm in lift.) . . immaculata Macq. 
Genus GYMNOSOMA Meig. 
Gymnosoma Meigen, in Illiger's Magazin fiir Iusektenknnde, Vol. IT, p. 278; 1803. 
In our single species the abdomen is yellow and marked with a black 
dorsal vitta or row of spots; dorsum of thorax of male in front of the 
suture yellowish pollinose and marked with four black vittse, but in 
the female the dorsum is destitute of pollen except the humeri and nar- 
row lateral margins; length, 5 to 8 mm. Grimsby, Canada; White 
Mountains and Franeonia, N. H. ; Maryland; District of Columbia; 
Virginia; Michigan; Agricultural College, Miss.; New Orleans, La.; 
Missouri: Kansas; Green River City, Wyo.; Colorado, Idaho, and Cali- 
fornia. (Essai sur les Myodaires, p. 237; 1830. Gymnosoma par 
Walker, List of Dipterous Insects, Part IV, p. 692; 1849. Gymnosoma 
filiola Loew, Dipt. Amer. Sept, Indigena, Centuria X, No. 66; 1872. 
Gymnosoma sp., Brauer and Bergenstamm in lift.) fuliginosa Desv. 
Genus PHORANTHA Rond. 
Phorantha Koudani, Dipterologite Italicae Prodromus, Vol. V, p. 21; 1862. 
Our species are black, the palpi and apex of proboscis sometimes 
yellow ; only one postsutural and one sternopleural macrocha'ta; wings 
not marked with brown beyond the base of the discal cell, costa nearly 
straight: 
1. Thorax subshining, almost destitute of pollen, not marked with dis- 
tinct black vitta 1 ; last section of the third vein nearly one half 
as long as the preceding section 2. 
Thorax opaque, densely gray pollinose, marked with four shining 
black vitta*; frontal vitta of female at the narrowest point 
slightly wider than the distance between the posterior ocelli, 
last section of the third vein one-fourth as long as the pre- 
ceding section, calypteres white; length 7 mm. Los Angeles 
County, Cal. (Tijdsch. voor Entomologie, Vol. XXXV, p. 185; 
1892 : Hyalomyia.) nigrens v. d. W. 
2. Calypteres whitish, second and third segments of abdomen thinly 
whitish pollinose, frontal vitta of female at the narrowest point 
less than one-third as wide as the distance between the posterior 
ocelli ; length, 2.5 too mm. Fort McLeod, British America ; Mary- 
land; southern Illinois; Georgia; Nueces, Tex.; South Dakota; 
