AMERICAN DIPTERA. 281 



40. Ovipositor much longer than its base 41. 



Not longer than its base 42. 



41. Ovipositor not more than twice as long, and gradually tapering 



from its large elongate base 8. nigripes Loew. 



9. ? semii'asciatus n. sp. 

 Slender, more than three times as long, and abruptly terminating 

 its small globose base. Western species. 



7. alternatus n. sp. 



42. Abdomen broad, opake, or subopake, with gray fasciae ; ovipositor 



longer than sixth segment 2. dubillS n. sp. 



Abdomen broad, nearly shining, only grayish tinged laterally ; 

 ovipositor not as long as sixth segment. 



4. confraternus Banks, n. sp. 

 Abdomen shining, cinereous only laterally and a median stripe on 

 the third segment ; femora not spinose. 



26. nitidiventris Loew. 

 Abdomen shining, cinereous only laterally ; femora distinctly spi- 

 nose 27 . lior vat hi Kertesz. 



43. Abdomen opake, or subopake, cinereous to nearly shining, but 



never polished 44. 



Abdomen polished, at most only base and lateral margins cinere- 

 ous 48. 



44. Legs yellow, at most only femora discolored medianly. 



Small species (3.0 mm.) 15. minor n. sp. 



Larger species (4.5 mm. and over) 45. 



Femora black, at most only extremities yellow 46. 



45. Antennae short, acute 16. atlaiiticus Hough. 



Antennae very long, white acuminate 14. aequus n. sp. 



46. Ovipositor extending to second segment. ..13. ? subopacus Loew. 

 Ovipositor shorter, hardly reaching apex of fifth 47. 



47. Abdomen opake, with gray fasciae 3. affinis n. sp. 



Abdomen and scutellum nearly shining, only grayish tinged later- 

 ally 4. confraternus Banks, n. sp. 



48. Legs entirely yellow ; femora slender ; ovipositor very short, with 



globose base 33. liouglrii Kert. 



Legs yellow ; femora much thickened ; base of ovipositor elongate. 



24. femoratus n. sp. 

 Femora black, or with extremities more or less yellow 49. 



49. Antennas with third joint black 50. 



Third joint yellow 32. lllteicornis n. sp. 



50. Ovipositor slender, curved, longer than, and abruptly terminating 



its elongate base (Fig. 86) 30. alpinus n. sp. 



Ovipositor short, abruptly terminating its large base ; femora 



mostly black (Fig 94) 28. angus n. sp. 



Ovipositor stout, gradually tampering from, its more or less elongate 



base; legs mostly yellow (Fig. 87)) 29. sororius n. sp. 



TRANS. AM. EST. SOC, XXXVI. (36) DECEMBER, 1910. 



