NORTH AMERICAN DIPTEHA. l-il 



Family MYCETOPHILID.E. 



1. — Coxie very strongly elongated (Mycetophilina) 4, 



Coxfe only moderately long (Sciarina) 2. 



2. — Wings hairy Tricliosia. 



Wings bare 3. 



3. — Joints of funicnlum of % round, with long pedicels and thick whorls of 



hair Zygoneura. 



Joints of funiculura round or elongate, not pedicelled, and only slightly 



hairy Sciara. 



4. — Fourth vein arising from fifth far from base of wing, and almost at its 



middle 5. 



Fourth vein arising from fifth very near to base of wing 12. 



5. — Upper branch of fork of third vein very long and oblique 6. 



Upper branch short, sometimes so steep that it appears like an extra cross- 

 vein 8. 



6. — Fork of third vein not petiolate, i. e., arising exactly where the small cross- 

 vein meets the third longitudinal 9Iycetobia. 



Fork of third vein petiolate, always arising at some distance behind junc- 

 tion of small cross-vein with third vein 7. 



7. — Fork of third vein longer than fork of fourth l>itoiiiyia. 



Fork of third vein shorter than that of fourth Ple^iiawtiiia. 



8. — Fork of fourth vein arising beyond the small cross-vein ...Bolitophila. 

 Fork of fourth vein arising above small cross-vein, and apparently from the 



third vein 9. 



9. — Antennse unusually long and slender, filiform Macrocera. 



A ntennte rather short, and usually also rather thickened 10. 



10. — Proboscis beak-like, elongate Asyiidiiliiiii. 



Proboscis not elongate 11. 



11. — Antennae broad, flattened ; palpi not incurvate Cero|>lalll!>i. 



Antennae not flattened ; palpi incurvate Platyiira. 



12. — Third vein furcate, the upper branch of the fork usually very steep (and 

 often arising so near to the base that it forms and closes a very small 



supernumerary cell in front of it) 13. 



Third vein simple 18. 



13. — Second longitudinal vein elongate, more so than in the other allied genera, 



conspicuous Eiidicraiia. 



Second vein shorter, not elongate 14. 



14. — Small cross-vein more than twice as long as prtefurca of third vein, and so 

 oblique that it appears like the beginning of the latter; the steep ba.'sal 

 part of third vein and the steep upper branch of fork of same ;ij)pearitig 



like two parallel cross-veins Tetraj;oii('iira. 



Small cross-vein only a little longer than, as long as, or shorter than praj- 

 furca of third vein, always moderately oblique, but never appearing 

 like beginning of latter; the steep basal part of third vein usually di- 

 vergent or convergent with upper branch of fork of same 15. 



15. — Costal vein reaching only to extremity of third longitudinal. .Sciopliila. 



Costal vein extending always somewhat, and often widely Iteyond extremity 



of third vein KJ. 



TK.^NS. AM. ENT. SOC. XIX. .JUNE, 1892. 



