Asilidie from Aden and its neighbourhood. 97 



rufous ; the tips of the femora and tibise, and the second and following 

 joints of the tarsi, more or less brownish ; the bristles of the tarsi 

 and some scattered bristles on the femora and tibia?, black. Halteres 

 yellow. Wings (fig. 13) slightly brownish, more obscure at the tip 

 and hind margin, with the central parts of the cells sometimes 

 clearer ; small cross-vein placed distinctly beyond the middle of the 

 discal cell. 



A single pair, from Haithalhim and Lahej. 



23. Ommatius tenellus, n. sp, ^ $ . 



Cinereous ; antennas black ; legs rufous ; the tip of the femora and 

 tibia?, and the tarsi black ; wings hyaline. 



Length 7 mm. 



Head (PI. III., fig. 14) broader than the thorax ; face white, 

 narrow ; mystax whitish, in the males with some long bristly hairs 

 of the same colour above it (in the single female these hairs are 

 blackish). Front and occiput grey ; the ocellar tubercle black. 

 Antennae black ; third joint ovate ; arista long, with a row of rather 

 long hairs on the imderside. Proboscis black. Thorax and scutellum 

 cinereous ; thoracic dorsum with distinct brown or blackish stripes ; 

 the median stripe double ; the lateral ones interrupted on the trans- 

 verse suture, thus forming two spots ; pleura? and metanotum grey ; 

 on the posterior part of the thorax and on the sides behind the 

 suture several whitish bristles ; the bristles before the halteres white. 

 Abdomen somewhat flattened, with parallel sides ; cinereous with 

 white incisions ; male genitalia small, dark rufous, laterally with 

 black hairs ; ovipositor of the female very short. Legs yellowish- 

 rufous ; the coxse grey ; the tips of the femora and tibise, to a more 

 or less extent, and the tarsi, with the exception of the basal joint, 

 brownish or black ; some weak yellowish hairs and bristles on the 

 tibia; and on the underside of the femora ; bristles of the tarsi black. 

 Halteres pale yellow. Wings (fig. 15) pure hyaline ; small cross- 

 vein on the middle or a little beyond the middle of the discal cell. 

 In one of the specimens the space between the costal vein and the 

 first vein is brownish, and the small cross-vein stands a little before 

 the middle of the discal cell ; but I see no other difference. 



Fairly common. Several specimens from Haithalhim 

 and Lahej. 



In its small size and the coloration of the legs this 

 species is allied to the East-Indian 0. argyrodiirus, 



TRANS. ENT. SOC.LOND. 1899. — PARTI. (APRIL) 7 



