1903] MELAXDER: — XORTH AMERICAN SPECIES OE NEMOThLUS I 73 



6. Body with purple tinge ; hind tibiae black in the middle; tip of tarsi black 



polyposus Say 

 Body shining black, not purplish ....... 7. 



7. Front immaculate; eyes subcontiguous ; base and apex of hind tibiae pale; 



anterior tibiae subfuscous carbonarius Loew 



Front bimaculate ; base of all the tibiae pale . . . tristis Bigot 



8. Pilose species with greenish luster ..... arator^ sp. n. 

 Bare or nearly so .......... 9- 



9. Eyes contiguous ; metallic blue-black ; front spotted with white 



cayiadensis Loew 

 Eyes' subcontiguous ; front black ...... 10. 



10. Shining black species nigrinus Fallen 



uni color Loew 

 Shining blue-green species crassus Loew 



11. Abdomen with black dorsal markings; thorax black with a lateral line; 



third vein simple . . . . . . . • ■ 12. 



Abdomen wholly whitish, unspotted ; third vein furcate . . 13. 



12. Thorax greenish black ; abdomen with two central black spots in the fourth 



and fifth segments ; posterior femora and tibiae brown in the middle 



flavicornis Johnson 



Thorax black ; abdomen with a basal black mark also ; legs largely black, 



tip of femora, base and tip of tibiae and tarsi whitish slossonae Johnson 



13. Proboscis, geniculate at the middle, the basal part enlarged; lateral line of 



thorax obsolete, humeral spot small . . . . . - 14. 



Proboscis geniculate before the middle . . . . . • 15- 



14. Legs yellow; antennae yellow, proboscis red . . hnmaciilatus ]o\m%ow 

 Femora at least blackened ; antennae black ; proboscis black 



trinoiatus, sp. n. 



15. Face comparatively short, black; thorax shining, pubescence rather erect; 



eyes depressed along line of meeting .... heUuIus, sp. n. 



Face longer, yellowish above ....... 16. 



16. Length 3 mm.; antennae yellow except tip; thorax greenish; front linear 



albif'ostris Macquart 

 Length 5 mm. ; antennae blackish ; thorax slaty black, subshining, with 

 appressed pubescence ; eyes contiguous, not depressed along line of meet- 

 ing . . . . . . . . . • wheeleri, sp. n. 



17. Abdomen above with whitish lines or spots; third vein furcate 18. 

 Abdomen above wholly black ; third vein not branched (except bruesii) 21. 



18. Markings of abdomen arranged in a median series of triangular spots ; head 



