8 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.60. 



L. Wings yellowish fumose ; front tibiae narrower in proportion 



to length xanthopus. 



LL. Wings dusky hyaline, front tibiae broader in proportion to 



length nervosus. 



II. Top of thorax yellow to rufous. 



M. Top of thorax only rufous; legs black rufithorax. 



MM. Whole thorax and legs pale, joints of latter dark-tipped longipes. 



HH. Abdomen, as well as thorax and legs, testaceous, with only minor dark 

 markings ; head black inaequalis. 



BIBIO ABBREVIATUS Loew. 



BiHo abhreviatus Loew (H.), Diptera Americae septentrionalis indigena, 

 Centuria, 5, No. 9, 1864, Compl. Work, p. 217 [District of Columbia]. 



Male. — Head, body, and coxae black, the head with dark, the 

 other i^arts with pale hair; femora and succeeding joints of legs 

 yellow to rufous, dark-tipped; the front tibiae almost wholly dark; 

 spurs pale, subequal; wings chiefly hyaline, the anterior veins and 

 stigma dark. 



Female. — The female differs in having shorter hair of head pale, 

 the coxae yellow to rufous and wings fumose. 



The distinguishing character of the species is the short hind meta- 

 tarsus, which in both sexes is distinctly shorter than the succeeding 

 three joints of tarsus combined; the hind tibiae of males are some- 

 what enlarged. 



Length of wing, 4-6 mm. 



Van Der Wulp has repeated the combination Bihio abhreviatus in 

 describing ® a new species from Argentina. 



Specimens examined were collected in Maryland, near the Dis- 

 trict of Columbia, and in Pennsylvania, Indiana, Michigan, Iowa, 

 and South Dakota (all from the latter State being very small). 



BIBIO ALBIPENNIS Say. 



B. [ihio'\ albipennis Say (Thomas), Desc. Dipt. U. S., Journ. Acad. Nat, 

 Sci. Phila., vol. 3, 1823, p. 78; Compl. Writings, vol. 2, 1859, p. 69 [Penn- 

 sylvania] . 



KEY TO SUBSPECIES OF ALBIPENNIS. 



A. Pile usually longer and more abundant, especially on males; western. 



B. albipennis hirtus. 

 AA. Pile shorter and less abundant ; eastern B. albipennis albipennis. 



BIBIO ALBIPENNIS ALBIPENNIS Say. 



Bibliographical reference same as for species. 

 Male. — Head, body, and legs black, humeral ridge more or less 

 marked with yellowish, legs brownish black distally, the tarsal joints 

 narrowly pale basally ; eyes with copious long, dark hair, remainder 

 of body, coxae and femora with the same, pale yellowish to gray, 

 tibiae with shorter dark hair; spurs of front tibiae very unequal, 



"Tijds. V. Ent., vol. 24 (1880-81), 1881, p. 145. 



