377 



organs or latcrad of them. The number of the tubercles is, however, 

 sufficient to indicate a specific difference. The anal appendages of the 

 abdomen are as in nwnUis. 



Imago ; Male and female. — Differ in color from monilis in being 

 generally paler, the light-colored parts being almost white and, as a 

 rule, the wings presenting a rather milky appearance. The difference 

 in the annulation of the legs I have indicated in the key. The basal 

 joint of the fore tarsus is slightly longer than the next two joints to- 

 gether, whereas in monilis it is slightly but distinctly shorter. The 

 apical portion of the lateral arm of the hypopygium is as shown in 

 Figure lo. Plate XXVIII, the subapical process ending in an acute 

 point. The wing venation and markings are almost identical in the 

 two species, the principal difference lying in the spots on the apical 

 half of the costa. In monilis there are generally three distinct spots, 

 as shown in Figure ii, Plate XXVII, while in illinoensis the first two 

 are fused or the second and third are indistinct. 



Length, 3.5-4.5 mm- 



Type locality : Junction of Illinois and Spoon rivers at Havana — 

 numerous examples, with various dates of capture extending from 

 May to end of September. Paratypes from Carbondale, 111., April 27, 

 1908, one specimen, and Algonquin, May 13, 1896 (W. A. Nason). 

 The only pupa which I have seen was taken in the Illinois River near 

 the shore at Havana in 191 3. Besides the Illinois examples I have 

 seen im.agines from Lake Delavan, Wisconsin, taken in September, 

 1892, which are in the State Laboratory collection, and several belong- 

 ing to the collection of the United States Bureau of Biological Sur- 

 vey, taken at Plummer's Island, Md., and Washington, D. C, in June 

 and August — October. The probability is that the species is widely 

 distributed, and the dates given above indicate that it occurs through- 

 out the entire summer and well into the fall. 



9. Tanypus venustus Coquillett 



Taniipus vemistus Coquillett, Proc. U. S. Nat. Mus., Vol. 25, 1902, p. 91. 



Male. — Brown-black. Head brownish yellow ; antennre and an- 

 tennal plumes brown, flagellum slightly paler; palpi yellow. Mesono- 

 tum opaque and silvery pollinose, vittai rather indistinct, the pollinos- 

 ity irregularly distributed, forming in i)laces spotlike markings; 

 pleune yellowish above, brown on lower portions, slightly shining; 

 scutellum yellow. Abdomen with apical third of each segment whit- 

 ish yellow ; hypopygium yellow. Legs yellow, a distinct preapical 

 band on femora, and a broad band near bases and a narrow one at 



