774 BOSTON JOURNAL 



Length less than one-fourth of an inch. 



A very common species. I have found their nests in [396] 

 the soft, decomposing sap-wood of the Oak and Hickory, between 

 the bark and the solid wood. Their cells are oval, horizontal, 

 not symmetrically disposed, though many are parallel. These 

 cells are composed of particles of the decayed wood, agglutinated 

 together. Each cell contains an individual, subsisting on a yel- 

 low pollen, enclosed with it by the parent. In the same assem- 

 blage are the young of all ages to the perfect insect. 



The male varies in having the tibiae and tarsi yellowish-white, 

 with more or less of green on the middle of the posterior tibiae. 



The preceding species, distinguished by their polished green 

 color, are also remarkable by the very obtuse emargination of 

 their eyes, or, in other words, the curvature of the inner side of 

 the eye : they might very properly constitute a division of the 

 genus. 



5. H. LIGATUS. — Black; tergum banded with whitish. 



Inhabits United States. 



9 Body black, with whitish cinereous hairs on the head and 

 .stethidium : wing-scale honey-yellow : wings hyaline, tinged with 

 yellowish towards the base ; postcostal nervure black ; first re- 

 current nervure entering the second cubital cellule near, but not 

 at the dividing nervure : metathorax at base having the depressed 

 surface granulated or very minutely lineated ; posterior face sub- 

 orbicular, slightly concave : tergum having the posterior margins 

 of the segments white with prostrate hair, beneath which the 

 surface is piceous : venter a little hairy ; posterior margins of 

 the segments obscurely piceous : feet tinged with piceous, paler 

 towards their tips ; the posterior with pale ferruginous hair. 



Length about three-tenths of an inch. 



^ Antennas beneath, ochi'eous, excepting the first and [397] 

 second joints : nasus, labrum and middle of the mandibles, yel- 

 low : wings with the nervures darker : tergum not so very obvi- 

 ously banded : feet black; tibiae and tarsi, yellow; the former 

 having a black spot on the anterior middle of the posterior pairs. 



Length three-tenths of an inch. 



A very abundant species. The male is a little longer than the 

 female. 



. [Vol. I. 



