ABTll. NOTES ON NEARCTIC BIBIONID FLIES — McATEE. 7 



AA. Inner spur of front tibia mucti siiorter tliaii outer. 



F. Hind metatarsus distinctly enlarged, almost as thicli as end of femur. 

 G. Legs brown to black, not distinctly bicolored. 



H. Thorax and legs pale-haired longipes. 



HH. Thorax and legs dark-haired slossonae. 



GG. Legs distinctly bicolored. 



I. Tibiae, hind femora, and basal tarsal joints pale, dark-tipped. 



inaequalis. 



II. All femora and succeeding joints yellow, dark-tipped fumipennis. 



FF. Hind metatarsus not distinctly enlarged, considerably less in diameter 



than end of femur. 



J. Legs almost entirely dark. 



K, Smaller species (wing, 4-5 mm.) ; first joint of hind tarsus but little 



longer than second tenuipes. 



KK. Larger species (wing, 5-9.5 mm.) ; first joint of hind tarsus twice 



as long as second albipennis. 



JJ. Legs distinctly bicolored. 



L. Only the femora (and front tibial spurs) yellow to rufous holtii. 



LL. More of legs yellow to rufous. 



M. Tibiae and tarsal joints rufous, dark-tipped, femora brown to 



black vestitus. 



MM. Femora and succeeding joints yellow^to rufous, dark-tipped. 

 N. Body usually pale-haired, leg joints pale, with dark tips. 



O. Wings hyaline to yellowish fumose; front tibiae narrower in 



proportion to length , xanthopus. 



00. Wings usually dusky hyaline; front tibiae broader in propor- 

 tion to length nervosus. 



NN. Body dark-haired; leg joints often considerably dark-clouded, 



tristls. 



KET TO THB SPECIH8 : FKMALBS. 



A. Inner spur of front tibia long, sometimes nearly as long as outer. 



B. Only the femora rufous ; wings blackish femoratus, 



BB. More of legs yellow to rufous. 

 C. Wings yellow brown, darker costally. 

 D. Smaller species (wing, 4-5-6.5 mm.). 



E. Hind metatarsus distinctly shorter than succeeding three joints to- 

 gether ; thorax dark abbreviatus. 



EE, Hind metatarsus about as long as succeeding three joints to- 

 gether; thorax chiefly yellow to rufous fratemtis. 



DD, Larger species (wing, 7.5-9.5 mm.) variabilis. 



CO. Wings smoky, blackish costally basalls. 



AA. Inner spur of front tibia much shorter than outer. 

 F. Body and legs brown to black, with pale hair. 



G. Smaller species (wing, 4-5 mm.) tenuipes, 



GG. Larger species (wing, 5.5-9.5 mm.) albipennis. 



FF. Body or legs in part yellow to rufous. 

 H. Abdomen black. 



I. Top of thorax chiefly or entirely black. 



J. Smaller species (wing, 5-6 mm.) slossonae. 



J J. Larger species (wing, 7.5-9 mm.). 



K. Entire anterior margin of mesonotum pale humeralis. 



KK. Humeral ridge only pale. 



