50 THE NORTH AMERICAN SPECIES OF DROSOPHILA. 



3. Costa pectinate; vibrissse large; two large orbitals Curlonotum 



Costa not pectinate; vibrissae and lower orbital minute or missing Apsinota 



4. Arista minutely pubescent 5 



Arista plumose 9 



Arista short pectinate; no prescutellars; bristles large Titanochceta 



Arista bare except for one long branch at base; no prescutellars; post verticals 



small CladochoEta 



5. No ocellar or preapical bristles; one pair of dorsocentrals; prescutellars present. 



Acletoxenus 

 Ocellars present 6 



6. Four pairs of dorsocentrals; a long propleural; two orbitals Bloesochoetophora 



One or two pairs of dorsocentrals; three orbitals 7 



7. Discal and second basal cells separated; front not unusually hairy Sinophthcdmus 



Discal and second basal cells confluent ; front with numerous small hairs 8 



8. Carina large; costa weak between third and fourth veins Gitona 



Carina small; costa well developed to apex of fourth vein Pseudiastata 



9. An extra cross-vein between third and fourth veins, near posterior cross-vein. . . Idiomyia 

 Only anterior cross- vein between third and fourth 10 



10. Proboscis longer than height of head; head broader than thorax Zygothrica 



Proboscis shorter than head ; head broad only in a few species of Chymomyza .... 11 



11. Two pairs of presutural dorsocentrals; distal costal break very deep Dettopsomyia 



No presutural dorsocentral macrochsetse 12 



12. Mesopleurse bristly; anal cell open at apex; metallic-colored species Camilla 



Mesopleurse bare 13 



13. Discal and second basal cells separated; postverticals small; prescutellars large. 



Slegana 

 Discal and second basal cells confluent 14 



14. Lower recUnate orbital as far from proclinate as from upper reclinate 15 



Lower reclinate orbital nearer proclinate than to upper reclinate 17 



15. Prescutellars weak or absent; face and carina very prominent Zaprion-tis 



Prescutellars large; face not protuberant 16 



J.6. Front covered with stout hairs; costa reaches fourth vein Pseudophortica 



Front not unusually hairy; costa weak or absent beyond apex of third vein. 



Leucophenga 



17. Lower reclinate orbital large, placed below procUnate; postverticals usually small; 



eyes bare or nearly so Chymomyza 



Lower reclinate orbital small, placed above procUnate, or, rarely, a trifle below it . . 18 



18. One large pair of dorsocentrals; mesonotum and scutellum unusually convex; 



a single bristle at distal costal break Mycodrosophila 



Not as above; almost always two pairs of large dorsocentrals 19 



19. Acrostichal hairs in not more than four rows in front of anterior dorsocentrals, 



not more than two between the dorsocentrals; slender species with long 



wings Scapiomyza 



Acrostichal hairs in six or more rows in front (except in D. opaca), four or more 



behind Drosophila 



In the account of each species that I have seen is a section headed 

 ''specimens examined." In most cases the name of the collector 

 follows each locality, in parentheses. When one name appears after 

 a State name for which several localities are recorded, then all the 

 records for that State are from that one collector. In some cases the 

 collector is unknown to me, and in these cases the museum in which 

 the specimens are deposited is usually given. In a very few cases 

 even this information is not supplied by my notes. Except for these 

 rare cases, any record without a collector's name is based on my own 



