FUNGUS GNATS. OF NORTH AMERICA. 167 



gg. Posterior margins of tergites black; fore 

 metatarsus longer than its tibia ; hypo- 

 pygium as figured (figs. 132, 136). 



12. imitans n. sp. 

 dd. Posterior margins of tergites yellow, or abdominal 

 segments unicolored, yellow or brown, 

 e. Abdomen with 2 or 3 spots on each segment ; 

 petiole of media shorter than Mo. 



13. biseriata. 

 ee. Abdomen not so marked. 



f. Dorsum of abdomen with a median row of 

 large spots which may be confluent, form- 

 ing a dorsal stripe ; middle coxs with 

 spurs ; fore metatarsus equal or longer than 

 the tibia, 

 g. Fore metatarsus i-io longer than the 

 tibia; hypopygium as figured (fig. 137) ; 

 length 6.5 mm. 14. maxima n. sp. 



gg. Fore metatarsus subequal to tibia in 

 length ; hypopygium as figured (fig. 

 135) ; length 4.5 mm. 



II. marginalis n. sp. 

 ff. Tergites each with a more or less yellow pos- 

 terior margin ; or wholly of one color, 

 g. Fore metatarsus is longer than the tibia, 

 h. Abdomen brown, sclerites faintly yel- 

 low margined posteriorly; length 4 

 mm. ; hypopygium as figured (fig. 

 138) ; cell Ri 2.5 times as long as 

 wide and half as long as the petiole 

 of the media. 15. sigma n. sp. 



hh. Abdomen not so marked. 



i. Subcostal crossvein proximad of the 

 middle of cell R^; only the pos- 

 terior margins of tergites yellow ; 

 length 6.5 mm. 14. maxima n. sp. 

 ii. Subcostal crossvein is near middle of 

 the cell Ri ; length 3.5 mm. ; both 

 anterior and posterior margins of 

 tergites yellow. 17. hirticoUis. 



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