310 DIPTERA OP NORTH AMERICA. [PART IV. 



wing of P. rufocincta). Antennae 16-jointed ; last joint very small. Tibiae 

 with strong, divaricate spurs at the tip ; empodia large. Thoracic suture 

 deeply sinuate. Abdomen of the male club-shaped at the tip, with a 

 coriaceous, often apparently double, forceps. 



Head transverse, sessile ; epistoma projecting, subtriangular, 

 rounded at the tip ; proboscis with very large suctorial flabs ; 

 palpi very long ; last joint whiplash-shaped, once and a half the 

 length of the three preceding joints taken together, or longer ; 

 among the three first joints the second is the longest. 1 Eyes 

 large, separated by a broad space on the upper and on the under 

 side of the head. The antennae of the male are comparatively 

 long ; bent backwards, they reach somewhat beyond the basis of 

 the abdomen ; those of the female are shorter ; they are sixteen - 

 jointed ; scapus short, the first joint being but little longer than 

 the second ; the first joint of the flagellum is cylindrical, twice 

 the length of the second ; the following joints are almost cylin- 

 drical, slightly decreasing in length towards the tip, clothed with 

 a microscopic down, and with scattered, verticillate hairs ; the last 

 joint is very small in the European species ; in the American P. 

 rufocincta it is hardly perceptible even in fresh specimens. The 

 collare is small, almost obsolete, concealed under the somewhat 

 projecting mesonotum ; the latter is gibbose ; the thoracic suture 

 forms a deep sinus in the middle, the bottom of which nearly 

 reaches the scutellum ; the sides of this sinus are prolonged 

 anteriorly in the shape of furrows, as far as the anterior margin 

 of the mesonotum ; the metathorax is large, convex. The abdo- 

 men of the male is narrow and rather abruptly club-shaped at the 

 tip ; the forceps of P. rufocincta, which I have examined upon 

 a fresh specimen, has the following structure : the last dorsal 

 segment of the abdomen has a strong excision in the middle ; 

 under it is the forceps, which consists of an elongated, curved, 

 coriaceous outside lobe, and an inner piece, apparently horny, 

 fastened to the lobe ; between the two halves of the forceps, the 

 horny aculeus is visible. In the European species the tip of the 

 abdomen shows four rather long, projecting appendages, having 



1 In describing the generic character, I had, besides P. rufocincta, speci- 

 mens of the European P. albimana and contaminata before me. Some data, 

 for instance those on the forceps and on the palpi, are taken from a fresh 

 specimen of P. rufocincta; its palpi, when extended backwards, could 

 almost reach the second abdominal segment. 



