Asilidss from Aden and its neighbourhood. 87 



I have no doubt that the above-quoted descriptions are 

 all founded on the same species. Macquart's specimens 

 were from the Cape, those of Low from Egypt, and those 

 of Walker from Mount Sinai. 



The genus Sisyrnodytes, Low, differs from nearly all 

 other Asilids by having the costal vein not prolonged 

 round the whole circumference of the wing, but terminated 

 a little beyond the end of the upper branch of the third 

 vein (see PI. II, fig. 10). Dasythrix is the only genus 

 among the Laphrinie that shows this peculiarity. 



10. Acnephahcm futile, n. s-p. $ $. 



Black ; thorax with white stripes and spots ; abdominal segments 

 with white front borders ; tibise and base of the tarsi rufous. 



Length 5-6 mm. 



Head greyish ; mystax white or whitish yellow, ascending to the 

 antennse ; beard, and hairs of the occiput white. Antennae black ; 

 the basal joints with whitish hairs. Proboscis shining black. 

 Thorax, scutellum and abdomen shining black ; on the thoracic 

 dorsum three longitudinal stripes, the sides, and some lateral trans- 

 verse stripes, whitish ; pleurae with a large whitish spot beneath the 

 shoulders and some others further behind ; the thorax is clothed 

 with short whitish hairs and has posteriorly many bristles of the 

 same colour ; the bristles before the halteres yellowish-white ; the 

 abdominal segments have white front borders ; on each side of the 

 first segment is a tuft of yellowish bristles ; male genitalia small? 

 somewhat pointed, rufous, with yellow hairs ; anal segment of the 

 female truncate. Legs rather robust ; coxae and femora black ; the 

 tip of the femora, the tibiae and the first tarsal joint rufous, the fol- 

 lowing joints of the tarsi gradually darker ; the hairs and bristles of 

 the legs, even those of the tarsi, yellowish-white. Halteres pale 

 yellow. Wings (PI. X, fig. 11) hyaline, iridescent, with black veins ; 

 all the posterior cells open, the third slightly enlarged and the fourth 

 narrowed towards the margin of the wing ; small cross-vein on the 

 middle of the discal cell ; third basal cell closed at the margin. 



A pair in coitu, from Aden. 



This species is closely allied to Dasypogon {Acnephalum) 

 andrenoides, Wied. (Auss. Zweifl. i, p. 403), but differs in 

 its smaller size, black antennae, abdomen not punctured 

 nor reddish at the sides, and its hyaline wings without 

 brownish picture. 



