50. ASILUS DETERMINATUS, n. s. _Mas et Foem._ Cinereo-niger, capite subaurato, antennis nigris, thorace vittis tribus cinereis, pedibus fulvis robustis, femoribus nigro vittatis, tibiis apice tarsisque nigris, alis fuscis, halteribus testaceis. _Mas._ Abdomine pilis basalibus luteis. _Foem._ Abdomine pilis basalibus cinereis dimidio apicali stylato. _Male and Female._ Cinereous black; head slightly gilded in front, with pale hairs beneath; epistoma not prominent; mystax with many pale, and above with a few black bristles; antennæ black; third joint lanceolate; arista nearly as long as all the preceding joints; thorax with three cinereous stripes, the lateral pair dilated towards the humerus on each side; pectus cinereous; legs tawny, stout; femora striped above with black; tarsi and tips of the tibiæ black; wings brown; veins black; halteres testaceous. _Male._ Abdomen with luteous hairs towards the base. _Female._ Abdomen with cinereous hairs towards the base; nearly half the apical part stylate. Length of the body 10-12 lines; of the wings 18-20 lines. 51. ASILUS INTRODUCENS, n. s. _Foem._ Cinereo-niger, capite aurato, antennis nigris, thorace vittis duabus lateribusque cinereis, abdomine fasciculis quatuor basalibus cinereis dimidio apicali stylato, pedibus nigris robustis rufo variis, alis fuscescentibus, halteribus fulvis. _Mas?_ Capite argenteo, abdomine fascia basali fasciculari fasciaque subapicali albidis latis, alis obscure cinereis. _Female._ Cinereous black; head gilded in front, with cinereous hairs beneath; epistoma slightly prominent; mystax with several gilded bristles, and above with a few black bristles; antennæ black; 3rd joint lanceolate, nearly as long as the arista; thorax with two cinereous stripes, which are dilated on each humerus; sides and pectus cinereous; abdomen with two cinereous tufts on each side at the base; nearly half the apical part stylate; legs black, stout; femora red beneath and partly above; tibiæ with a broad red band; wings brownish, somewhat paler towards the base and about the borders of the posterior areolets; veins black; halteres tawny. _Male?_ Head silvery in front; mystax with several white, and above with a few black bristles; abdomen with a broad whitish tufted band at the base, and with a broad whitish subapical band; wings dark cinereous, partly paler, as in the female. Length of the body 8-12 lines; of the wings 12-16 lines. 52. ASILUS AREOLARIS, n. s. _Mas._ Cinereo-niger, capite aurato, antennis nigris basi fulvis, thorace vittis tribus cinereis, abdomine apice nigro nitente segmentis cinereo marginatis, pedibus fulvis, tarsis posterioribus nigris, alis fuscescenti-cinereis pallido lituratis triente basali albido, halteribus testaceis. _Foem?_ Antennarum articulo 3° fusiformi, alis fuscescentibus hyalino lituratis.