_Male._ Black. Head gilded; mystax with a few black and several gilded bristles; sutures of the thorax, scutellum, sides, pectus, hind borders of the abdominal segments, and underside hoary; tibiae tawny, with black tips; wings cinereous, blackish along the costa and towards the tips, veins black; halteres ferruginous. Length of the body 6--6-1/2 lines; of the wings 11-12 lines. 41. OMMATIUS LUCIFER, n. s. _Mas._ AEneo-niger, capite argenteo, pectore albido, abdominis segmentis ferrugineo marginatis, pedibus testaceis, femoribus nigro-vittatis, tarsis nigris, alis limpidis apice nigricantibus costa atra apud medium incrassata, halteribus testaceis. _Male._ Bronze-black. Head silvery in front; mystax with a few black and a few whitish bristles; pectus whitish; hind borders of the abdominal segments ferruginous; legs testaceous; femora striped with black; tarsi black, ferruginous at the base; wings limpid, blackish at the tips; costa deep black, incrassated in the middle; halteres testaceous. Length of the body 6 lines; of the wings 11 lines. 42. OMMATIUS RETRAHENS, n. s. _Foem._ Cinereo-niger, facie argentea, pectore albido, pedibus testaceis, tarsis, femoribus tibiisque apice femoribusque posticis nigris, alis limpidis apice subcinereis, halteribus testaceis. _Female._ Cinereous-black. Head silvery white in front; mystax with very few white and black bristles; pectus whitish; legs testaceous; tips of the anterior femora and of the middle tibiae black; hind femora and hind tarsi black; anterior tarsi and hind tibiae black, testaceous towards the base; wings limpid, slightly cinereous towards the tips; veins black; halteres testaceous. Length of the body 4 lines; of the wings 7 lines. Gen. LEPTOGASTER, _Meigen._ 43. LEPTOGASTER FERRUGINEUS, n. s. _Mas._ Ferrugineus, pectore albo, abdomine nigro, segmentorum marginibus ventreque testaceis, pedibus fulvis, femoribus apice nigris, tibiis piceo vittatis, tibiis posticis tarsisque nigris basi testaceis, alis sublimpidis, halteribus testaceis apice piceis. _Male._ Ferruginous. Head pale, gilded in front, hind side and pectus white; mouth and antennae tawny, the latter blackish towards the tips; abdomen black; hind borders of the segments and under side testaceous; legs tawny; anterior femora with a testaceous band before the tips, which are black; hind femora and anterior tibiae striped with piceous, the latter black towards the tips; tarsi and hind tibiae black, testaceous at the base; wings very slightly greyish, veins black; halteres testaceous, piceous towards the tips. Length of the body 7 lines; of the wings 10 lines. 44. LEPTOGASTER LONGIPES, n. s. _Mas._ Ferrugineus, pectore albido, abdomine piceo, segmentis apice fulvescentibus, pedibus anterioribus fulvescentibus, posticis piceis longissimis, femoribus posticis basi testaceis, alis subcinereis basi obscurioribus costa venisque nigris, halteribus testaceis apice nigris.