160 



Subfamily BIBIONIN^E. 



Nothing of importance can be added to the characters given in 

 the above table separating the two subfamilies. The species are 

 always larger and much more robustly built, more pubescent, and 

 more generally distributed than the SCATOPSIN^E. 



Table of Genera. 



A. Third longitudinal vein forked. Posterior 

 cross-vein distinctly nearer the base than 

 the anterior cross- vein. 



B. The 3rd vein forks just beyond the an- 



terior cross-vein, the upper branch almost 

 parallel to the lower one ; the 4th vein 

 forks exactly at the anterior cross-vein 



or, literally speaking, below it, the cross- [p. 160. 



vein connecting with the upper branch . . PLECIOMYIA, Brun., 

 BB. The 3rd vein forks some little distance 

 beyond the anterior cross-vein, the upper 

 branch sometimes approximately paral- 

 lel to it, sometimes almost erect ; the 

 4th vein forked some distance beyond [p. 162. 



the anterior cross-vein PLECIA, Wied., 



AA. Third longitudinal vein not forked. Pos- 

 terior cross-vein distinctly beyond the an- 

 terior cross- vein. 



C. Fore tibiae in both sexes with a pro- 



minent tooth-like spine at the tip; 

 dorsum of thorax never with a dentate 



ridge BIBIO, Geoff., p. 166. 



CC. Fore tibiae in both sexes with a circlet 

 of spines at the tip instead of the 

 spiny process, also often with spines 

 on the middle of the fore tibiae ; dorsum 



of thorax with two dentate transverse fp. 176. 



ridges DILOPHUS, Mg., 



Genus PLECIOMYIA, Brun. 



Pledomyia, Brunetti, Rec. Ind. Mus. iv, p. 269 (1911). 

 GENOTYPE, Penthetria melanaspis, Wied. 



Allied to Plecia, Wied., from which it differs by the 4th longi- 

 tudinal vein rather broadly forking immediately at the point of 

 contact with the anterior cross-vein. The 3rd longitudinal vein 

 forks almost immediately beyond the anterior cross-vein, the 

 upper branch lying almost parallel with the lower one. The 

 antenna has twelve joints, two short normally shaped basal ones 

 forming the scape ; a comparatively long first flagellar joint, 

 followed by eight others of a flattened bead-shape, with a 



