274 J. M. ALDRICH. 



15. Inner daw of male fore tarsus enlarged and l)ent so as t<i form a small hold- 



ing organ [W. I.. Mex.). ■ l*elaMtoiieuru!<t ungiiiciilatiis Aid. 

 Claw not so modified IH. 



16. Orbital cilia pale below 26. 



Orbital cilia black 17. 



17. Tips of hind femora inftiscated above 18. 



Tips of hind femora not infuscated ... 21. 



18. Dorsum of abdomen deej) violet in color; hirgf^ species (Cal., Ariz., S. D.). 



I'elaistoneui'us oyaiieiiN Wheeler. 

 Dorsum of abdomen not violet 19. 



19. Dorsum of thorax violet (N. Y., Ma.ss., Fhi.). 



Pelastoneiiriis laint^llatiiN Loew. 

 Dorsum of thorax not violet (N. Y., Vn\., Fla.). 



Pela!«toiieiiriis longicaiida Loew. 



20. Fore coxse black (N. Y.). l*eIaMl«>iieui'ii»> ahbrevialus Loew. 



Fore coxse yellow, except at base (N. Y., 111., Mex.). 



Pelastoneurus lu^ubriii^ Loew. 



21. Hypopygium short, the lamell* divided, forming four long filaments iKans., 



IS. D.) Pelastoneiiriis kaiif>>ensis Aldiich. 



Uypopygium of different structure 22. 



22. Dorsum of thorax opaque brown, with two fine grey lines; white spots ab- 



sent from transverse suture (N. Y., 111., Mex.). 



Pelasfoiifuriis liigiibrii^ Loew. 

 Dorsum more or less shining, the white spots distinct -23. 



23. Face of male in narrowest place not one-tenth the width of the head (Mex.). 



Sarcioiiiis flavicoxa Aldrich. 

 Face of male much wider 24. 



24. Face of male brown, lamellse forked (Tex.). 



Pelastoneiiriis furcifer Loew. 

 Face of male brown, lamellae not forked (La.). 



Pelastoiieurns proxiiniis u. sp. 

 Face of male white or whitish 25. 



25. Thoracic dorsum deep violet in color (Fla., Ga., La., D. C). 



Pelsistoiieurus la'^tus Loew. 

 Dorsum only a little violet behind ; hypopygium slender, lamellpe small, oval 



(La.) PolaKtoiieuruN parvus u. sp. 



Dorsum only a little violet behind ; hypoi)ygium thickened, tlie tip of the 

 black lamella drawn out iuto a long, curved, black process (Quebec). 

 Pelastoiieurns falcatuM n. sp. 



26. Face of male with a brown strii)e in middle, sides greyish white (Middle 



States, Mex. PelasJoiieurus cogiiatus Loew. 



Face of male not so marked 27. 



27. Lamallae of hypopygium triangular, the upper basal angle prolonged in a 



long filament, projecting outwards or backwards ■ ■ • 28. 



Lamellae of ditierent structure 29. 



28. Color bright green ; arista plumose (W. I., Mex.). 



Pelastoneiirus argeiitiler Aldrich. 

 Color blight green ; arista pubescent (W. I.. Mex.). 



Paraclius fililer Aldrich. 

 Color bronze-green ( Mass.) Paraeliiis vit'iiiiiM n. sp. 



