582 PROCEEDINGS OF THE ACADEMY OF [Aug., 



6. Posterior orbital margin black (Europe), . . . succinda, Panz. 

 Posterior orbital margin broadly yellow, 7. 



7. Mesothorax red without yellow stripes; legs red and yellow, 8. 



Mesothorax red with yellow stripes, 10. 



Mesothorax black, with or without stripes, 11. 



8. Third submarginal cell short; basal nervure considerably basad 



of trans verso-medial, 9. 



Third submarginal cell long; basal nervure almost meeting trans- 

 verso-medial, citrina, Cress., var. rufula, Ckll. 



9. Third antennal joint long; fourth considerably longer than fifth, 



7norrisoni, Cress., var. flageUaris, Ckll. 

 Third antennal joint shorter; fourth scarcely longer than fifth, 



morrisoni, Cress. 



10. Third antennal joint scarcely shorter than fourth; fifth about 



equal to third, luteoloides , Rob. 



Third antennal joint very much shorter than fourth, . luteola, Lep. 



11. Face square, tegulse yellow, 12. 



Face broader than long, 1,3. 



12. Third submarginal cell very narrow; flagellum mostly dark, 



sulphurata, Smith. 

 Third submarginal cell broad below; flagellum fulvous-red be- 

 neath, citrina, Cress, var. 



13. Lateral face-marks receding from orbits above; end of flagellum 



black above, citrina, Cress. 



Lateral face-marks following orbits to top of eye ; end of flagellum 

 not black above, civilis, Cress. 



The S]3ecies of this group (Xanthidium and part of Holonomada of 

 Robertson) are very variable, and in my preliminary examination of 

 them I separated out several supposed species which I have now con- 

 cluded to treat as varieties only. 



Nomada dontariae (Rob.). 



I have a male from southern Illinois, sent to me several years ago as 

 A^. luteola by Mr. Robertson. As it clearly possesses the characters 

 assigned to dentarios. by Robertson, I assume it to be that insect. 



Nomada vincta, Say. 



I have before me three specimens, all from Illinois, belonging to the 

 Acad. Nat. Sciences Phila. The male is marked by Mr. Viereck: 

 "mixed with affabilis; flagellum thicker than in affabilis." One of the 

 females has the mesothorax red, with a very broad black stripe in the 

 middle; the other has it black, with a red stripe on each side above 

 the tegu]a3. The former specimen is marked by Mr. Viereck: "mixed 

 with luteola." Robertson says that N. vincta is autumnal ; Mr. Fowler's 

 California ^'vincta,"^ flying in May, is presumably another species. 



