521 



slightly browned ; mid and hind tibire with the usual black apical comb. 

 Wings clear, veins colorless. Halteres yellow. 



Eyes bare ; antenna slightly longer than head and thorax com- 

 bined; palpi 4-jointed. Hypopygium as in Figure 14, Plate XXXVII. 

 Legs moderately stout ; fore tarsi without long hairs, basal joint five 

 sevenths as long as fore tibiae ; pulvilli and empodia large ; mid and 

 hind legs with short hairs. Third vein straight, ending slightly be- 

 yond beginning of apical curve of wing and directly above apex of 

 upper branch of cubitus; cross vein slightly before middle of wing, 

 and distinctly, though not greatly, in front of fork of cubitus; poste- 

 rior branch of cubitus nearly straight ; distance from cross vein to 

 apex of first subequal to that from apex of first to apex of third ; sec- 

 ond vein (R2) distinct. 



Length, 3.25 mm. 



Type locality, Dubois, 111., April 24, 19 14 (C. A. Hart and J. R. 

 Malloch). 



Differs from sonicns in venation and color particularly. 



Orthocladius Van der Wulp, sens, stric. 



Only a few North American species are left in the genus Ortho- 

 cladius as restricted by Kieffer, and these, as far as our Illinois spe- 

 cies are concerned, are of an almost unicolorous black except in the 

 females, which occasionally have the ground color of the thorax yel- 

 lowish. In addition to this almost constant unicolorous character the 

 species are so very similar in structural details that at times one is 

 doubtful as to whether the slight differences are those between indi- 

 viduals of a single species or distinctions that are of specific import- 

 ance. I have divided the species before me upon the characters given 

 in the synoptic key, and believe that those selected are really of spe- 

 cific value, though difficult to distinguish. The empodia, when pres- 

 ent, are always very small — a character that readily separates the spe- 

 cies from Cainpfocladitis. 



Key to Species in Collection (Males) 



1. Wing with cross vein subparallel with first vein (PI. XXXIX. Fig. 



12) ; basal portion of lateral arm of hypopygium with poorly de- 

 veloped process on inner side 1. suhparallelus. 



— Wing with cross vein almost at right angles to first vein (PI. 



XXXIX. Fig. 11) ; or basal portion of lateral arm of hypo- 

 pygium with well-developed process on inner side 2 



2. Fore tarsi with dense and very long hairs 2. pilipes. 



— Fore tarsi with at most sparse hairs which are, except in nivoriun- 



dus, but little longer than the joints which bear them 3 



