186 THE ENTOMOLOGIST. 



8. Lateral face-marks above receding from or not ap- 

 proaching orbital margin 9. 



Lateral face-marks above continuous along orbital 

 margin ........ 22. 



i). Lateral face-marks ending above in a broad oblique 



truncation ; scape dilated, light in front . . 10. 

 Lateral face-marks ending narrowly or in a knob . 11. 



10. Face-marks white ...... antennata. 



Face-marks lemon-yellow ..... varifrons. 



11. Tubercles wholly dark; upward prolongation of 



lateral face-marks entirely separate from orbital 

 margin, narrow and not swollen at end . . 12. 

 Tubercles partly light 13. 



12. Lateral face-marks not filling space between clypeus 



and orbit ........ saniculee. 



Lateral face-marks filling space between clypeus 



and orbit . . . . . . . .12 a. 



12a. Mesothorax pubescent, wings tinged greyish . . subdigitata. 

 Mesothorax naked, wings tinged brownish . . ditjitata. 



13. Upward extension of lateral face-marks wholly 



away from orbital margin, ending in a large knob 



curving over antennae ; scape light in front . bakeri. 



Upward extension of face-marks not ending in a 



large knob curving over antenna? . . . 14. 

 11. Upward extension of face-marks wholly separated 



from orbital margin, even at the base . . 15. 



Upward extension of face-marks curvingaway from 



orbital margin at the base . . . . .16. 



15. Wings clear or not brownish, face yellow . . rudbeckia. 

 "Wings brownish tinged, face yellowish white . ruidosensis. 



16. Tibite and tarsi wholly reddish orange . . . labiatifrons. 

 Not so 17. 



17. Supra-clypeal mark much longer than broad . . 18. 

 Supra-clypeal mark not or hardly longer than broad fallax. 



18. Small species, with the upward extension of lateral 



face-marks diverging from orbit but itself little 

 curved, and not greatly prolonged ... 19. 

 Larger species, with the upward extension of lateral 

 face-marks narrow and curved .... 20. 



19. Upward extension of lateral face-marks rapidly 



diverging from orbit fygmaa. 



Upward extension of lateral face-marks slowly 

 diverging from orbit ...... mesillcc. 



20. First abdominal segment smooth ; end of lateral 



face-marks above on a smooth shining space . vertical is. 

 First abdominal segment punctured . . . 21. 



21. Somewhat larger, face broader, face-marks creamy 



white . . . . . . . . tridens. 



Somewhat smaller, face narrower, face-marks 

 strongly yellow tridentida. 



22. Supra-clypeal mark broad and short, but little 



longer than broad ...... 24. 



