Robertson — North American Bees. 329 



Agapostemon aeruginosas Cresson, Synopsis, 293, 1887. 



Agapostemon nigricornis Robertson, Trans. Am. Ent. Soc. XX, 147, $^, 



1893. 

 Halictus splendens Dalla Torre, Cat. Hym. X, 85, 1896. 

 Agapostemon aeruginosus Dalla Torre, Cat. Hym. X, 97, 1896. 

 Agapostemon nigricornis Dalla Torre, Cat. Hym. X, 97, 1896. 



$>. — Large, golden-green, the abdomen often showing 

 bluish ; metathorax with a triangular space on disc which is 

 less coarsely reticulated ; mesonotum densely and finely punc- 

 tured, or more sparsely and coarsely so ; scutellum with large 

 scattered punctures, the intervening spaces densely and finely 

 punctured, or shining and almost impunctate; wings 

 uniformly rufo-hyaline, or the apical margins darker. 



g. — Wings and metathorax as in the female; anterior and 

 middle trochanters yellow, sometimes more or less blackish 

 above and behind, posterior green, subcampanulate; femora 

 yellow, usually with a little blackish at base behind, middle 

 sometimes with spot at tip, posterior strongly incrassate, about 

 one-half as wide as long ; anterior and middle tibiae with a 

 brownish streak behind, sometimes wanting on first, hind 

 tibiae black at base, streaked beyond and with a spot at tip 

 exteriorly, a streak towards tips within ; abdomen black, with 

 a brown spot at base, six fasciate, ventral segments with yel- 

 low basal fasciae, usually wanting on last, third from last 

 short, thickened, widely emarginate, hind metatarsi presenting 

 a dentiform angle. Length 11-13 mm. 



25 5, 17 $ specimens; Can., Mass., N. Y., Pa., Va.,N. C, 

 Ga., Fla., Ohio, Mich., 111., Neb., Ks., Tex. 



The following are sex names of any one of the four pre- 

 ceding species. It is fairly impossible to determine them 

 without seeing the insects on which they were based. In that 

 case the first two would probably replace names above adopted. 



Apis sericea Forster, Nov. Spec. Ins. I, 91, tf, 1771. 



Andrena nigricornis Fabricius, Ent. Syst. II, 313, $, 1793. 



Centris nigricornis Fabricius, Syst. Piez., 360, (J 1 , 1804. 



Halictus nigricornis Say, Bost. Journ. I, 394, J> , 1837, Lee. Edit. II, 772. 



Halictus sericea Say, Bost. Journ. I, 394, tf, 1837, Lee. Edit. II, 772. 



Agapostemon tricolor Cresson, Trans. Am. Ent. Soc. IV, 255, <^, 1872, 



Agapostemon nigricornis Cresson, Synopsis, 293, tf, 1889. 



Agapostemon sericea Cresson, Synopsis, 293, tf, 1889. 



Agapostemon sericea Robertson, Trans. Am. Ent. Soc. XXII, 118, tf 1895. 



Apis sericea Dalla Torre, Cat. Hym. X, 612, tf , 1896. 



