487 



17. Legs fuscous or brownish 18 



— Legs yellowish or whitish 19 



18. Basal joint of fore tarsi about one seventh longer than fore tibiae 



1. nigripilus. 



— Basal joint of fore tarsi nearly one half longer than fore tibige. . . . 



2. dives. 



19. Abdominal segments with pale posterior margins 



9. ohediens. 



— Abdominal segments without pale posterior margins 



10. flavicauda. 



20. Basal joint of fore tarsi at least twice as long as fore tibi© 21 



— Basal joint of fore tarsi less than twice as long as fore tibia? 23 



21. Basal joint of fore tarsi twice as long as fore tibiffi; mesonotum 



with distinct vitti^ 6. pimo. 



— Basal joint of fore tarsi distinctly more than twice as long as fore 



tibiae ; mesonotum without vittffi 22 



22. Larger species, more than 2.5 mm. in length 3. neoflavellus. 



— Small species, 1.5-2 mm. in length 4. flavellus. 



23. Basal joint of fore tarsi less than one half longer than fore tibige .... 



See 13 



— Basal joint of fore tarsi more than one half longer than fore tibiae. . 



See 15 



I. Tanytarsus nigripilus Johannsen 



Tanytarsus nigripilus Johannsen, Bull. 86, N. Y. State Mas., 1905, p. 287. 



Male. — Black, slightly shining. Tibi?e, tarsi, and knobs of hal- 

 teres brown-black. Wings clear, veins brown. 



Antepenultimate joint of palpi almost as long as the next two 

 joints together. Pronotum narrow, not continued to upper margin 

 of mesonotum. Hypopygium as in Figure 2, Plate XXXVL Legs 

 slender; fore tarsi with long hairs, basal joint about one sixth longer 

 than fore tibiae (38 : 32) ; mid and hind legs w'ith long hairs. Third 

 vein ending distinctly in front of apex of wdng; cubitus forking be- 

 low cross vein ; anal angle of wing w^eak ; surface hairs distinct. 



Female. — Agrees with the male except that the tibiae, tarsi, and 

 halteres are paler, and the wings rather broader. 



Length, 3-4 mm. 



Illinois localities, IMuncie, April 27 — May 24, and Easton, May 

 J, 1914 (C. A. Hart and J. R. ^lalloch). 



Originally described from Ithaca, N. Y. (April), and Washing- 

 ton State. 



The early stages are unknown. 



