307 



4. The costal vein reaches to the tip of the third longitudinal vein. 5 

 The costal vein reaches to the tip of the fourth vein. . . 6 



5. Tip of male abdomen with two elongated, upwardly curved bris- 



tles; two fronto-orbital bristles present. . . Dichseta. 



Tip of male abdomen without such bristles; a single orbito-frontal 



bristle present (6). ....... Notiphila. 



6. Abdomen broad, nearly circular in outline ; palpi broad ; arista 



pectinate (12). ....... Discomyza. 



Not such flies. .......... 7 



7. Face on upper part flat or gently convex, not carinate. . 8 

 Face distinctly carinate above. .... .11 



8. Third antennal joint longer than broad (1, 2). Psilopa. 

 Third antennal joint rounded, not longer than broad. . . 9 



9. Front with two pairs of bristles in the middle below the ocelli, di- 



rected forward. . ..... Paratissa. 



Front not with such bristles. ....... 10 



10. Mouth of large size; arista pectinate. . . . Ptilomyia. 

 Mouth small; arista bare; four pairs of strongly developed dorso- 



central bristles present; anal cell small but distinguishable (25, 

 35) Pelomyia.* 



11. Oral opening large; three or four bristles on either side of the face 



below. . . . . . . . . . . .12 



Oral opening not large. ........ 13 



12. Clypeus prominent ; ocellar bristles inserted above lowermost 



ocellus (4). . . . . . . . Parephydra. 



Clypeus small or hidden (33, 34) . .... Ilythea. 



13. Clypeus prominent; face gibbous below, . . . .15 

 Clypeus projecting but little from oral cavity. . . .14 



14. Eyes long; cheeks narrow; face feebly or not at all gibbous (21, 



22). Discocerin a - 



Eyes round; cheeks broad; face gibbous; scutellum with four bris- 

 tles (3) Allotrichoma. 



15. Arista bare ; third and fourth veins gently convergent distally; 



head without strong bristles (3O, 31) . . . Mosillus. 

 Arista pectinate; third and fourth veins not at all convergent (11). 



Athyroglossa. 



f I suspect that this genus belongs with the Agromyzidae. I have 

 seen specimens from Massachusetts, scarcely distinguishable 

 specifically, in which the second basal cell is complete. 



