20 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 74 



in having interrupted silvery basal crossbands on the abdominal seg- 

 ments. The head structure is very similar and both have the first 

 posterior cell ending in the apex of the wing. The following descrip- 

 tion is as complete as can be made from the type ; the species is cer- 

 tainly I'ecognizable from this on account of the striking thoracic 

 crossband. 



Male. — Hypopleurals and postscutellum well developed. Front 

 at narrowest 0.07 of head width, or just about the width of ocellar 

 triangle ; the paraf rontals are very narrow, so that the frontal stripe 

 at its narrowest is wider than one of them. Eyes bare, the facets 

 rather large in the region above the middle and toward the median 

 line of the head. The front was apparentlj^ a little prominent, and 

 the cheek was certainly rather broad, about one-third the eye height 

 as nearly as can be estimated. Vibrissae well developed, at or near 

 epistoma. Palpi of normal size, rather brown, proboscis short, 

 fleshy. The orbit is white or probably silvery all the way round the 

 eye; paraf acial at least as wide as third antennal joint, apparently 

 with a few minute black hairs in a single row. Antennae black, 

 third joint one and one-half times the second, red at base; arista 

 plumose, its base thickened. Frontal bristles beginning far before 

 the ocelli and ending barely below the attachment of the antennae, 

 perhaps even before it. The thorax shows very little on account 

 of its damaged conditions, except the silvery crossband, which lies 

 against the suture, occupying over one-third of the space to the 

 anterior edge of the mesonotum and at the sides expanding to hind 

 edge of humeri; on the pleura it includes the posterior half of the 

 mesopieura and a part of the sternopleura. 



Abdomen black ; second and third segments with wide basal inter- 

 rupted crossbands of white or perhaps silvery pollen; the median 

 interruption is narrow at extreme base, widening posteriorl3\ First 

 segment with a row of about 10 rather widely spaced slender mar- 

 ginal bristles, second and third segments with scars of a similar row 

 but perhaps stouter. No discals. Fourth segment in bad condition, 

 but apparently has some pale pollen at base and a fcAV apical 

 bristles. Genitalia small, black, concealed between the large plates 

 of the fifth sternite. 



Wing hyaline, first vein bare, third with one or two hairs at base ; 

 hind cross vein very straight, halfway between small and bend of 

 fourth vein, the latter very oblique, concave beyond, ending in the 

 exact apex, the first posterior cell open. The second vein ends near 

 tip of third so that the costal section before it is about three times as 

 long as the one beyond, Wiedemann gives the length as 4 mm. 



The species is not represented in the United States National 

 Museum. 



