270 J. M. ALDRICH. 



15. The face of the male extends below the eyes, hanging down before the 



mouth, apron like Poly iiiedon Osten Sacken. 



The face of the male reaches about as far as the lower edge of the eyes; head 



vertically eulongated Tachytreclliis Stannius. 



Face of the male reaching as far as the lower edge of the eyes, but the head 



not elongated Paracliusi Loew. 



16. Third and fourth veins parallel towards the tip ••■ 17- 



Third and fourth veins distinctly convergent 19. 



17. Bristles of thorax yellow Tlirypticu!* Gerstaecker. 



Bristles of thorax black 18. 



18. First antennal joint bare above PelorO|»eodes Wheeler. 



First antennal joint hairy above Gyiuiiopterniis Loew. 



19. The last segment of the fourth vein gradually ajiproacliing the third. 



HereostoiuiiM Loew. 

 Last segment in the middle abruptly cuiviug forward, then gradually resum- 

 ing its former course, ending near the third vein. 



Paraclius Loew. 



20. Costal vein extending only to the tip of the third vein, the latter part of the 



fourth vein evanescent AsyndetiiS Loew. 



Costal and fourth veins normal 21. 



21. First antennal joint hairy above 22. 



First antennal joint bare above 26. 



22. Fourth vein towards the tip strongly curved towards the the third, nearly 



reaching it in the margin Pela!«toneiiriis Loew. 



Fourth vein parallel with the third, or slightly convergent 23. 



23. Arista dorsal, face very narrow, palpi small Anepsius Loew. 



Arista dorsal, face wide, palpi large 24. 



Arista nearly or quite at the tip of the large, pointed third joint 25. 



24. Arista plumose Pliylarclius Aid rich. 



Arista pubescent l>iost raciis Loew. 



25. Proterior cross-vein distant about its own length from tlie end of the fifth 



vein Hypocliarassiis Mik. 



Posterior cross-vein much n\()re than its own length from tip of fifth vein. 



Argyra Macquart. 



26. A concave or distiuctly flattened, bare space before the scutellum 27. 



Thoracic dorsum convex as usual 31. 



27. Bristles of thorax pale yellow Chrysolimuw Loew. 



Bristles black, rarely brownish 28. 



28. Fourth vein parallel with the third beyond the cross-vein, or nearly so. .29. 

 Fourth vein converging towards the thii-d, either gradually or by a double 



curve .... '^'eiiri^soiia Rondani. 



29. Acrostichal bristles present only at the anterior edge of thorax, very mi- 



nute Xaiitliochlorus Loew. 



Acrostichal bristles well develojied, two-rowed 30. 



30. Very minute, blackish, opaque species Aclialcus Loew. 



Small, yellow species Xaiitliiua Aldrich. 



■•■■" ThrypticHs minor Aid. from St. Vinctent, W. I., has the 3rd and 4th veins some- 

 what convergent. 



