148 MR. E. E. AUSTEX ON NEW DIPTEROUS INSECTS. [Jan. 17, 



vestige of a tubercle, clothed with pale Avhitish pile, and cinereous 

 pollinose on the sides. Front metallic blue at the sides, bronze- 

 black in the middle, clothed with blackish pile ; the apex of the 

 ani^le of the eyes and a narrow margin on each side cinereous 

 pollinose : anteniiiferous process not prominent. Antennce yellow, 

 small ; third joint somewhat oblong in shape, roimded at the tip, 

 which, Mith a rather broad upper margin, is bro\vn. Occiput 

 cinereous, fringed with silvery hairs. Thora.v and scuteUmn 

 metallic bi'onze-bro\m, the latter steely on the hind margin ; 

 pleurse bronze anteriorly, pale metallic bluish ^hite behind the 

 base of the wings ; post-alar callosities reddish : thorax sparsely 

 clothed with very short dark pile, the scutellum with longer 

 pale pile. Ahdomen slender, spatulate, steely on first segment, 

 elsewhere brown ; the typical specimen has a narrow transverse 

 faint yellow baud, widely divided in the middle, at the base of 

 the fourth segment ; genitalia small, concealed : a tuft of whitish 

 hairs on each side of the first segment, and the second and third 

 segments with a fringe of shorter pale hairs on each side ; the 

 abdomen elsewhere nearly bare. Anterior legs yellow, the third 

 and fourth joints of the tarsi, and the outer side of the femora 

 towards the base, brownish ; second and tldrd pairs of legs brown, 

 the bases and tips of the femora, tjie basal third of the posterior 

 tibia?, the \^hole of the middle tibire, the first two joints of the 

 middle tarsi, the tip of the first and the whole of the second joint 

 of the posterior tarsi, pale yellow : the middle femora ^\■ith a 

 fringe of rather long pale bail's behind ; the posterior femora with 

 a similar but shorter fringe of hair on the outer and inner side. 

 Third longitudinal vein of the \\ing straight. 



Brazil, region of the Amazon (Bates) ■ t\\"o specimens, both 

 males. 



This species is not closely allied to any other known to me ; in 

 the markings of the wings it resembles B. higoti, which, however, 

 distinguishes itself at once by the reddish colour of the basal half 

 of the abdomen, as also by the rudimentary condition of its alula?. 



Baccha pumila, sp. n. (Plate Y. fig. 12, ^ .) 



S 2 . Length 65 mm. 



Yellow, sinning : centre of dorsum of the thorax shining hlaclc^ 

 with three cinereous ■pollinose stripes ; abdomen contracted, but pet 

 stout, at the base, then spatulate ; ivith darh brown cross-bands and 

 lineate markings, Legs yelloio ; posterior femora in the c? ivitJi 

 the basal third and a band near the tip, posterior tibial ivith a fainter 

 band near the base, brown; these marhings are much fainter in the 

 5 , and in another S the extreme base of the posterior femora is 

 yellow. Wings hyaline ; subcostal cell brown : alulce rudimentary. 



Face and cheel-s pale opalescent yellow, a narrow shimmering 

 ^^hite border next the eyes, when the face is viewed from above ; 

 facial tubercle relatively large, at least in the S , rounded ; in the 

 cJ , frontal triangle and anteuniferous projection pale shining 

 yellow with a black dot above the base of the antennse j vertical 



