1903] MELAXDER : — XORTH AMERICAN SPECIES OF .SEMOTELUS 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 ..... carhonariiis Loew 



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



8. Pilose species with greenish luster ..... amfor, sp. n. 

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



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



canadensis Loew 

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



10. Shining black species ...... nigriniis Fallen 



unicolor Loew 

 Shining blue-green species ...... crassns 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 



Jiavicornis 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 . immaculatits ]o\\x\^ors. 

 Femora at least blackened ; antennae black ; proboscis black 



trinotatus , sp. n. 



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



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



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



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



albirosfris Macquart 

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

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

 ing .......... wheekri, sp. n. 



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

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



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



