_Male._ Cinereous black; head gilded in front, clothed with black hairs beneath; epistoma prominent; mystax with many gilded bristles, and above with a few black bristles; antennæ black, tawny towards the base; thorax with three slender cinereous stripes, sides and pectus cinereous; abdomen black and shining at the tip, hind borders of the segments cinereous; legs tawny; posterior tarsi black; wings brownish cinereous, with paler marks in most of the areolets, white on more than one-third of the length from the base; veins black, tawny towards base; halteres testaceous. _Female?_ Epistoma less prominent; third joint of the antennæ fusiform, hardly half the length of the arista; wings brownish; marginal areolets with a nearly colourless spot in each. Length of the body 10 lines; of the wings 18 lines. 53. ASILUS TENUICORNIS, n. s. _Foem._ Cinereus, capite argenteo, antennis testaceis parvis, thorace vittis duabus fuscescentibus, abdomine obscure cinereo segmentis testaceo marginatis, pedibus fulvis, genubus tarsisque nigris, alis cinereis apice obscurioribus, halteribus testaceis. _Female._ Cinereous; head silvery white in front; epistoma very slightly prominent; mystax with some white bristles, and above with very few black bristles: antennæ testaceous; 3rd joint conical, much shorter than the 1st joint, and not more than one-fourth of the length of the arista; thorax with two brownish stripes; abdomen dark cinereous; hind borders of the segments testaceous; legs tawny; tarsi, except at the base and knees, black: wings cinereous, dark cinereous towards the tips; veins black, tawny towards the base; halteres testaceous. Length of the body 8 lines; of the wings 14 lines. Gen. OMMATIUS, _Illiger_. 54. OMMATIUS SCITULUS, n. s. _Mas et Foem._ Fulvus, gracilis, capite cinereo antice albo, antennis nigris basi fulvis, thoracis disco cinereo-nigro, pectore testaceo, abdominis segmentis pallido marginatis, alis cinereis, halteribus testaceis. _Male and Female._ Tawny, slender; head cinereous above, white in front; mystax with several white bristles; antennæ black, tawny towards the base. 3rd joint lanceolate, arista not longer than the 3rd joint; disk of the thorax cinereous black; pectus testaceous; hind borders of the abdominal segments pale; tarsi black towards the tips; wings cinereous; veins black, tawny towards the base; halteres testaceous. Length of the body 6-7 lines; of the wings 11-12 lines. 55. OMMATIUS STRICTUS, n. s. _Mas._ Niger, angustus capite argenteo, pectore albido-cinereo, abdomine fusco maculis trigonis nigris, segmentis albido marginatis, pedibus fulvis, genibus tarsisque nigris, alis subcinereis extus nigricantibus, halteribus testaceis.