Empididae. 31 



and the dividing line is rather sharp; at the posterior margin of the 

 eye the small facets are continued somewhat upwards. In the 

 dichoptic males the facets are of the same size above and below. 

 The common incisure in the middle of the inner eye-margin is pre- 

 sent, often it is larger in the male than in the female. The vertex 

 is small but prominent, and bears three ocelli and some shorter or 

 longer hairs. The antennæ are inserted quite near to each other, 

 about in the middle of the front side, rarely higher above (e. g. flavd) ; 

 they are five-jointed , the first joint is cylindrical, the second shorter, 

 almost globular, the third more or less elongated, attenuated towards 

 the apex and thus of more or less conical shape , and it is compres- 

 sed; the two last joints form a shorter or longer, but always some- 

 what short style, the first joint of which is the shortest. The two 

 basal joints have shorter or longer, more or less bristly hairs. Epi- 

 stoma is broader or narrower, sometimes very narrow (e. g. flava); 

 when the antennæ are inserted above the middle it is somewhat 

 high; it is flat, or sometimes a little arched, or the lower edge is a 

 little projecting. The jowls are very small, not descending below 

 the eyes, but only present as a narrow rim. The oral cone is some- 

 what small; clypeus consists of two chitinous lists meeting above, 

 and it is thus almost horse-shoe-shaped ; it stretches from the epistoma 

 to the base of labrum. Proboscis is shorter or longer, from some- 

 what shorter than the head is high to about twice as long; it is di- 

 rected more or less vertically dovvnwards. Labrum is about of the 

 length of labium when the latter is in the normal position; it is strongly 

 chitinised, semitubular, high at the base, pointed towards the apex 

 and here divided into three pointed lobes which can be spread or 

 closed. Hypopharynx is about of the length of labium, semitubular, 

 dilated towards the end but the very apex forms a small, protruding 

 point. The maxillæ have long laciniæ formed as thread-like blades 

 and pointed at the apex; they are somewhat shorter than hypopharynx ; 

 the maxillary palpi are somewhat long, cylindrical, one-jointed; they 

 are directed upwards and haired. Labium is only weakly chitinised; 

 the labella are as a rule more than half as long as the basal part 

 of labium, not or only slightly broader, more or less oval, and haired 

 below; they are cleft to their base but connected with the basal 

 part of labium by an oblique line, so that they are longer below 

 than above. Labium has a very long connecting membrane at the 

 base, so that it may be drawn much longer out than its own length, 

 but in rest this membrane is folded in, and likewise the oral cone, 

 the clypeus then being withdrawn into the oral aperture. Thorax is 

 rectangular somewhat^ sometimes highly, arched above; prothorax 



