

(ORTHORRHAPHA BRACHYCERA.) 



(PLATYGExNYA.) 

 HETERODACTYLA. 



PROGEPHALA. 



Asilidae. 



Head short, flat or slightly excavated behind; it is broad and 

 nearly ahvays broader than high; it is as broad as, or somewhat 

 broader than, thorax. The vertex is strongly excavated in a saddle- 

 shaped way, and thus the eyes are prominent above. The head is 

 sHghtly arched in front and very often there is a smaller or larger 

 callus on the epistoma, reaching more or less up towards the an- 

 tennæ; this callus is set with strong, downwards curved bristles, the 

 epistomal beard. Jowls small, generally only slightly descending below 

 the eyes, rarely more. Antennæ nearly always inserted near to each 

 other and more or less above the middle, sometimes very high and 

 then the frons is very short; the antennæ are sometimes placed on 

 an antennal tubercle; they are three- to five-jointed; when more 

 than three-jointed the last or the two last joints form a blunt or 

 pointed style, or an arista; when this is tv^'o-jointed the basal joint 

 is short, and sometimes the style is indistinctly two-jointed. Eyes 

 separated in both sexes, the face being more or less broad; the facets 

 "in the front part of the eye, from the inner eye-margin outwards, 

 more or less enlarged in both sexes, sometimes only very slightly. 

 Three ocelli present, situated on an ocellar tubercle on the excavated 

 vertex. Ocellar bristles present or absent; a row of occipito-ocellar 

 bristles along the posterior eye-margin. The parts of the head sur- 

 rounding the oral aperture only slightly membranous, thus no oral 

 cone is formed; on the occiput there is a membranous part below 

 the occipital foramen in which part the united stipites of the maxillæ 

 lie. The clypeus is marked off on the lower part of the epistoma; 

 it is triangular or rounded upwards and flat or often impressed, below 

 it has a small membranous part. The proboscis varies in length from 



Diplera Danica. II. 1 



