NORTH AMERICAN HYMENOPTERA. 317 



smooth aud somewhat elevated ; abdomen shining, without patches of appressed 

 white pubescence; wings hyaline, nervures dull testaceous, the second cubital 

 cell not strongly narrowed to marginal ; tegulae testaceous ; posterior tibial spur 

 with three or four long teeth. Length 6 — 7 mm. 



%. — Slender; a little more shining; antennse long, testaceous beneath; disc 

 of raetathorax more elevated at apex ; clypeus anteriorly, labrum and mandibles, 

 generally, pale yellow; knees, sometimes, and tarsi houey-yellow ; nervures 

 fuscous; tegulae black, or testaceous. Length 5 — 6 mm. 



Hah. — New Hampshire, Illinois, Nevada, California ; twenty 9 , 

 twelve % specimens. Closely resembles H. i-maculatus. 



Halictns paliistris 9- — Blue-green, especially the head and thorax, 

 clothed with long, thin, white pubescence; head broad, clypeus not produced; 

 mesothorax strongly, not closely punctured ; metathorax short, broad, strongly 

 truncate; truucatiou smooth; disc rough, with irregular longitudinal rugae, 

 bounded posteriorly by a salient rim; abdomen shining, finely and sparsely 

 punctured, clothed with whitish pubescence, except ou the discs of the first two 

 or three segments; apical margins of segments rather broadly testaceous; wings 

 whitish hyaline, nervures testaceous, often pale; tegulae brown, punctured ; legs 

 brown or fuscous. Length 6 — 8 mm. 



%. — Resembles the female; antennae long, more or less testaceous beneath: 

 metathorax rougher, the disc with the salient rim forming a semicircular enclo- 

 sure ; abdomen less greenish; tarsi pale testaceous. Length 6 — 8 mm. 



Hab. — New Hampshire, Massachusetts, Connecticut, New York, 

 Maryland, District of Columbia, Tennessee, Illinois; thirty-nine 

 9 , twenty % specimens. Easily recognized by its metathorax and 

 punctured tegulse. 



Halictns Cressonii 9 • — Head and thorax green, abdomen black ; head 

 broad, clypeus not produced ; mesothorax strongly punctured, clothed with thin 

 fulvous pubescence; metathorax blue-green, narrow, strongly truncate; trunca- 

 tion with superior lateral angles salient; disc rough, with coarse reticulations ; 

 abdomen shining, almost impunctate, apical margins of segments hardly testa- 

 ceous, triangular patch on each side of base of second, and whole of remaining 

 segments with close, pale fulvous pubescence; wings yellowish hyaline, tegulae 

 and nervures honey-yellow, second and third submarginal cells of about equal 

 width. Length 6 — 7 mm. 



^ . — Resembles the female ; antennae black ; metathorax less strongly truncate : 

 tegulae and nervures darker; tarsi honey-yellow. Length 5 — 6 mm. 



jffab. — Canada, Maine, Massachusetts, Connecticut, New York, 

 Illinois, Montana, Washington ; twenty-three 9 , two % specimens. 

 Dedicated to Mr. E. T. Cresson. 



Halil'tlis albipeiiiiis 9-— Head and thorax greenish, abdomen brown- 

 ish ; clypeus produced; mesothorax coarsely and rather sparsely punctured. 

 I'lothed with thin white pubescence; metathorax not shaiply truncate, disc with 

 longitudiiuil rugae, slightly elevated posteriorly: abdomen depressed, shining. 



