1893.] ME, E. E. AtrSTEIf OS lOIW DIPTEEOrS IlfSECTS. 149 



triangle long, narrow, cinereous pollinose. Front in the 2 , except 

 the posterior third, which is cinereous pollinose, pale shining yel- 

 low, with a blackish-brown dot in the centre line above the base 

 of the antennae, from which a narrow brown median stripe runs 

 back to the poUiuose portion : ocelli remote from the vertex in 

 both sexes. Antennce yellow, third joint roimded at the tip ; arista 

 black. Occiput cinereous pollinose. The median cinereous polli- 

 nose stripe on the thorax is much narrower, and also some« hat 

 longer, than the lateral ones, but all the stripes terminate at a 

 considerable distance from tlie scutellum : fi-ont portion of the 

 pleurae metallic yellow ; pectus, posterior portion of the pleurae, 

 and metanotum steely black. Scutellum yellow ; a narrow stripe 

 along the anterior margin, tapering towards the sides, which it 

 does not quite reach, black. First segment of the abdomen with a 

 dark brown posterior border, the lateral protuberances with a tuft 

 of yellow pile ; second segment with the anterior and posterior 

 thirds (in the typical 6 rather more than the anterior third) dark 

 brown, so that the yeUow ground-colour is restricted to a baud 

 across the middle ; this may appear to be narrowly divided in the 

 median line ; third and fourth segments \Aith the hind margin, 

 the median thu-d of which is expanded (considerably so in the 

 typical d' ), a quadrate area occupying each posterior angle, a some- 

 what clavate mark projecting inwards and forwards from these, and 

 a median narrow stripe dark brown ; in the typical 2 the median 

 stripe does not quite reach the anterior margin of the segment, 

 while the " clavate " markings are narrower and less clavate than 

 in the 6 : in a second S in the collection the median stripe is 

 much broader, and also does not quite reach the anterior margin ; 

 on the fifth segment the markings are precisely similar, except 

 that the brown posterior mai-gin and the quadrate areas in the 

 posterior angles are almost obsolete, and that (in the typical speci- 

 mens at least) the median stripe reaches the anterior margin of the 

 segment in both sexes : sixth segment yellow. Tliird longitudinal 

 vein of the wings somewhat sinuate, convex forwards above the 

 distal half of the first posterior cell ; terminal portion of fourth 

 vein bounding the first posterior cell only slightly oblique ; pos- 

 terior cross-vein straight. 



Brazil, region of the Amazons {Bates) : three specimens. 



This species is distinguished by its size and markings from any 

 other known to me. 



Group II. 

 Baccha silacea, sp. n. (Plate Y. fig. 13, c? .) 



(S . Length 10 mm. 



Tliorax dull, clothed with deme pollen of pale sienna colour, with 

 narrow leaden stripes; a somewhat sluuphj defined median pyriform 

 area on the p)ectus greenish bronze; abdomen fiattened, but little con- 

 tracted basally, rvfous ocJiraceous, with orange-ochraceous stripes; 

 front with an obtuse antenniferous projection, marked with a round 

 blach spot : alulce of full size. 



