ART. 13 AMERICAN GENUS MICROPHTHALMA ALDRICH 7 



bare; palpi yellow; beard yellow. Pollen of thorax and sciitellum 

 rather greenish, on the humeri yellowish-gray; the black stripes of 

 the mesonotum are very distinct from all angles, the inner ones in- 

 terrupted at the suture and extending only a short distance beyond 

 it, the outer ones widely separated at the suture in two portions ; the 

 hindmost of these runs to a point as far back as the last intraalar. 

 Scutellum with two lateral bristles and a large decussate apical pair. 



The pollen of the abdomen is rather uniform, but thinner and 

 darker along the hind edge of the segments, wdiile at the anterior 

 edge in some lights an indistinct paler crossband is barely evident; 

 first segment without median marginals ; second with one pair, large 

 and erect; third with a large marginal row of eight; fourth with a 

 somewhat irregular discal row of 8 or 10 and an apical row of the 

 same number but smaller. Legs black, all the tibiae reddish in the 

 middle, the middle ones with three bristles on the outer front side; 

 the hind tibiae with two or three bristles on the outer hind side, the 

 one at the middle rather strkingly elongated, equal to the longest 

 one on the middle tibia. 



Wings deep brown, fading out to some extent along the hind edge 

 and apex, the hind cross vein and apical cross vein, however, quite 

 strongly bordered ; third vein with half a dozen bristles crowded to- 

 gether at the base. Calypters brown with narrow, yellow border. 

 Length, 9 mm. 



Described from two females collected by C. H. T. Townsend on 

 Huascaray Ridge, Jaen Province, Peru; altitude 7,000 feet. Date 

 of collecting, September 21 and 22. 



Type.— Female, Cat. No. 28863, U.S.N.M. 



DEXIOSOMA VIBRISSATUM Van der Wulp 



DexwHonia vibrissatum Van der Wulp, Biologia, Dipt., vol. 2, 1891, p. 244, 

 pi. 5, fig. 1.3. — GioLio-Tos, Mem. Reale Accad. Sci. Torino, ser. 2, vol. 44, 1893, 

 p. 63. 



Originally described from Tabasco, Mexico; Giglio-Tos reported 

 it from Teapa and Tuxpango, Mexico. Townsend labelled the gray 

 New Mexican form of disjuncta as Microphthalma vibrissata, 

 but two specimens recently received of a widely different species 

 seem to fit much better. These are females from Higuito, Costa Rica, 

 collected by Pablo Schild. Unfortunately both have lost the third 

 antennal joint, but the shortness of the second indicates that the 

 third was probably more than three times the second, as Van der 

 Wulp says. The first posterior cell opens much nearer the apex than 

 in any of the species of Microphthalma., so that the distance between 

 the tips of the second and third veins is more than twice that between 

 the tip of third and the exact apex of the wing. According to 

 Van der Wulp, the arista is densely plumose, which with the an- 



