458 CYRTIDiE 



Thorax strongly arched, with none of the calli very prominent (unless 

 from colour) though the postalar calli are large and conspicuous ; pubescence 

 abundant, adpressed and coarse. Scutellum shorter than in Oncodes, and with 

 hardly any flat disc. 



Abdomen inflated oval, conico-globular, with five obvious segments : pubescence 

 very short and adpressed. Genitalia of the male more dilated than in Oncodes. 



Legs rather short and stout, quite simple and without any spurs or processes ; 

 tarsi as in Oncodes but the claws even longer, and the pulvilli sliorter and more 

 pad -like. 



Wings shorter and smaller in the male than in the female ; venation (fig. 266) 

 very difficult to homologise, but with a simple (mediastinal) vein near the costa, 

 then a long (subcostal) vein from which the prsefurca issues before the middle 

 of the wing ; a radial vein may arise from the prsefurca (fig. 260 F), or may be 

 vaguely indicated (fig. 267), or may be quite absent (fig. 266) ; a wide open fork 

 includes the tip of the wing, of which the upper branch is probably the end piece of 

 the cubital vein, and the lower branch an end piece of the discal vein ; below this 

 come two simple long veins (lower branch of discal and postical), and these long 

 veins are connected by one conspicuous rather long apparent cross-vein between 

 the cubital and discal and another between the discal and postical, and the 

 venation ends with a straight simple anal vein ; there is no trace of a discal cell ; 

 the posterior veins hardly reach the wingmargin ; posterior cells three if the 

 cell which includes the wing-tip be one ; aluhe large. Squamae (thoracal) exceed- 

 ingly large, of apparently thinner texture than in Oncodes, and without any 

 long woolly pubescence on the surface ; alar squamae small. Halteres completely 

 covered by the squama;. 



This genus is easily distinguished from Oncodes by the vertical position 

 of the autennse and by the venation; no other genus of Cyrtidce can 

 possibly be confounded with it. The larvae are parasitic on spiders 

 {Tegenaria agilis, etc.). 



Acroccra is represented in Europe by about five fairly well distinguished 

 species (of which two have only recently been described by Pokorny), 

 though several more names occur in the list ; the species have not been 

 well distinguished (as is the case in many genera of Cyrtidce) because in 

 so many cases they are imperfectly known. A. globulus is the only well- 

 known one with the venation as in fig. 266, and therefore should be easily 

 recognised. Nine species are recorded from N. America, but I have not 

 noticed any other records. 



Synonymy. — Mik endeavoured in 1886 (Wien. ent. Zeit., v., 276) to separate 

 Acrocera into two genera, founded on the presence or absence of a radial vein, and 

 gave the name of Paracrocera to the group in which the radial vein was absent. 

 Osten Sacken (Berl. ent. Zeitschr., xl., 323) has shown that Mik was both hasty 

 and careless in this action ; hasty, inasmuch as specimens of Acrocera occur in which 

 the radial vein is represented by a basal stump or by an incomplete end without any 

 base (fig. 267) ; careless, inasmuch as he founded Paracrocera mainly on A. globulus 

 which was the only species known when JNIeigen founded the genus Acrocera, and 

 which must therefore under any circumstances retain the name of Acrocera and 

 be its typical species. 



1. A. globulus Panzer. Wings hyaline; radial vein obsolete. Legs 

 yellow with the tip of the tarsi black. (Fig. 267.) 



A small almost globular fly ; very distinct from any other 

 British species except Oncodes, in which the venation of the 

 wings is very distinct and the antennas are quite differently 

 placed. 



