4 PEOCEEDINGS OF THE NATIONAL MUSEUM. vol. Go 



arciiation of the fourth vein, before and beyond the latter vein is 

 widely bordered with yellow. Length, including appendages, 7 mm. ; 

 of the wing, the same. 



" Feraale. — ^Antennae much shorter, the third joint a little longer 

 than the other two, arista apical, a little longer than in the male. 

 Abdomen of five equal segments. Legs destitute of striking modifica- 

 tions, however, the spines under the fore femora are as large as in 

 the male. Wings as in the male. Length 7.2 mm." 



A male, collected at Palo Alto, California, October 11, 1905, J. M. 

 Aldrich, collector. A male and female taken in same locality Octo- 

 ber 11, 1906, by R. W. Doane, collector. 



2Vy06.— Male; allotype female. Cat. No. 26042, U.S.N.M. 



Type locality. — Salt marshes near Palo Alto, California, October 

 7, 1905. 



Originally described from three specimens. 



Also from salt marshes, San Francisco Bay, October 11, 1906, R. 

 W. Doane, collector. Yellowstone Park Upper Geyser Basin, Au- 

 gust 7, 1918, A. L, Melander, collector (A. L. M.). Great Salt Lake, 

 Utah, M. C. Van Duzee, collector (C. W. J.). 



2. SCELLUS EXUSTUS (Walker). 



Plate 1, fig. 4; plate 2, figs. 12 and 18, plate 3, fig. 25. 



Medeterus exustus Walker, Insecta Saundersiana, Diptera, vol. 1. p. 211. 

 Scelius exustus Walker, Aldkich, Entomological News, 1907, April, p. 135. 

 SceUus exustus Walkkr, Neue Beitr., pt. 8, p. 71, species 1. 



" Male and female. — Thoracis dorso aeneo-nigro opaco, abdomine 

 supreo, later versus viridi, nitidissimo, halteribus nigris, alis ni- 

 gricantibus adversus costam nigris. lamellis analibus maris albis, in 

 basi nigris, apicem versus flavis, in summo apice puncto nigro 

 notatis. 



" The upper side of the thoi'iix bronze-black, opaque ; the abdomen 

 copper-colored, literally green, very bright; halteres black; wings 

 blackish, toward the fore margin entirely black ; the anal appendages 

 of the male are white, near the root black, toward the tip yellow, at 

 the extreme tip with a black spot. Long. corp. 0.22. Long. al. 

 0.26. Syn. Medeterus exustiiS' Walker. Dipt. Saund. 211. 



" Male. — Black. The face rather narrow, opaque from a bright 

 ocher-yellow dust. Antennae black. Front covered with white dust. 

 The middle of the upper side of the thorax is, at least in my speci- 

 men, black, opaque, and exhibits some traces of gray dust; toward 

 the lateral margin it is more bright and shoAvs a less distinct cop- 

 pery reflection; on the lateral margin itself there is a broad longi- 

 tudinal stripe covered with white dust. Scutellum with two bristles, 

 opaque ujion the middle, with a thin, almost imperceptible coat of 



