\ 



North American Hymenoptera. 303 



2. P. architectus. Dark purple ; wings hyaline. 

 Inhabits Ohio. 



9 Body dark bluish-purple, somewhat hairy : head 

 black In front, with short, dense, yellowish-cinereous hair: 

 mandibles at tip piceous : tving-scale dark piceous : wings 

 hyaline, nervures blackish : second and third cubital cel- 

 lules not unusually contracted at the radial cellule, but 

 almost equal in that part: feet black: tergum^ anal seg- 

 ment polished. 



Length about three tenths of an inch. 



o 



This insect forms neat mud nests under prostrate logs 

 and stones. They consist of short cylinders, agglutinated 

 together alternately, and each composed of little pellets of 

 mud, compressed, or rather appressed to each other. 

 When these are adjusted to their places on the edge of 

 the cylinder, each has a fusiform shape and the slender 

 end of one laps over that of another, and the convex part 

 of the pellet of the succeeding layer is placed against this 

 duplicature so as to restore the equality of the edge. 

 This arrangement gives the surface an alternate appear- 



■ 



ance. 



The basal series of transverse nervures is very slightly 

 dislocated. 



3. P. higuttatusy Fabr. The individual described by 

 Fabricius appears to be a female. Coquebert gives its 

 leng;th at nine twentieths of an inch, but it sometimes ex- 

 ceeds half an Inch in length. The male is over three 

 tenths of an inch in length ; it is destitute of the anterior 

 white strlga of the thorax, and the tip of the tergum has 

 a white reflection ; the posterior half of the metathorax 

 also has a w^hite reflection. The basal series of trans- 

 verse nervures is not dislocated, in this species. 



4. P. Upidus. Black ; abdomen and wings purplish. 



