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Show 136 ME. E. E. AUSTEN ON NEW DIPTEEOUS INSECTS. [Jan. 17, species like B. rubricosa, Wied., and B. conjuncta, Wied., in the same genus as B. elongata, Fab., when, for instance, what Fallen called Scceva hyalinata is distinguished generically from Syrphus ribesii, Linn., or when Ocyptamus, Macq., is allowed to retain its independence. Group I. B A C C H A NUBILIPENNIS, n. sp. (Plate IV. figs 7, 9, o* $, and Plate V. fig. 14, head of 6 •) cT $ . Length : d 12^ to 14£ mm., $ 12| to 1 3 | m m. Face and cheeks yellow, with yellow pollen and pale yellow pile. Cheeks in J sometimes narrowly blackish immediately below the eyes. A prominent, rounded, and sharply-defined facial tubercle, commencing halfway down the face; sometimes an indistinct brown stripe between it and the antennae. Antennas orange ; third joint large, ovate, larger in the $ than in the S • A very pronounced antenniferous process, shining black above, and orauge-yellow immediately above the base of the antennae; the orange-yellow area is larger in the $ ; the projection is truncate and flattened in front, and pilose on the sides only. Front in J greenish black, with yellow pollen, and vertical triangle black; in 2 shiniug black, with a narrow triangular area on each side in front yellow pollinose. Pile on front blackish in <S , yellowish in 5 , shorter in the latter than in the former. Occiput with a fringe of pale yellow hairs. Thorax shining black; the collar of hair in front pale yellow; elsewhere nearly bare. Humeri and postalar callosities brownish; pleurae, with a broad vertical stripe of golden pollen in front of the suture; the stripe has a reddish ground; pleurae behind the wings silvery pollinose. Scutellum polished dark brown on the disc, more or less yellowish, semi-translucent, behind. General colour of the abdomen metallic black (browner in $ ) , sometimes with a distinct bluish sheen; the abdomen is broadest in the fourth segment. The first segment has outstanding pale yellow hairs on each side ; elsewhere the abdomen is clothed with very short appressed black pile. First segment black, browner and with an edging of yellow in the $ ; second segment with a yellow basal baud, notched in the median line behind, and with an interrupted brownish-yellow band near the tip, the latter often scarcely visible in the J1; third segment with a conspicuous transverse yelloiu band, occupying about the middle third of the segment, but slightly nearer the base; the remaining segments wholly metallic black ; male genitalia small and concealed. Lsgs orange-yellow ; posterior femora slightly darker, dark brown above and below on the distal half, but orange at the tips ; posterior tibiae reddish on basal third, then dark brown ; posterior tarsi dark brow'n on basal two-thirds of first joint, then whitish yellow. Wings infuscated, dark brown in the middle, and usually darker in the o* than in the $ ; in the $ the wings show a faint secondary infusca-tion at the tips, above the third .vein ; an area at the base on the |