40 PROCEEDINGS OF THE NATIONAL MUSEUM vol.82 



mesopleura finely punctured and distinctly shagreened, more defi- 

 nitely so posteriorly, the upper part (eps 2) longitudinally striate, 

 but very finely so and with the white hairs so closely appressed that 

 it is difficult to distinguish the sculpture. Abdomen exclusive of the 

 petiole distinctly longer than head and thorax to apex of propodeum, 

 the petiole subequal to the hind femur in length, with the dorsal 

 surface convex in center and slightly sulcate along each side, the 

 laterodorsal edges sharply carinate, lateroventral edges similarly 

 formed and the sides slightly concave or sulcate; sixth tergite with 

 a quite distinct raised line around apex and continued forward about 

 one fourth of the length of the tergite so that there is quite a marked 

 resemblance to the typical pygidium of the females of the genus. 

 Legs normal, hind coxae elevated at bases on inner side, but not car- 

 inate. Wings normal. 



Female. — Antennal flagellum narrower at base than in the male, 

 the basal segment about as long as the next two combined on under- 

 side. Face less densely haired, the clypeus without definite central 

 emargination and with a narrow transverse ridge a little before apex 

 in center ; f rons less shining on sides above and more regularly punc- 

 tured over all. Upper part of mesopleura more coarsely longitu- 

 dinally striate, the hairs less dense than in male; propodeum more 

 coarsely rugoso-reticulate, especially outside of the enclosure. Petiole 

 of the abdomen slightlj^ shorter and thicker than in the male, sim- 

 ilarly formed. Legs stronger than in male, the spinose armature also 

 stronger, the series of yellow spines on the posterior side of the fore 

 metatarsus quite noticeably stronger. 



Length, 9.5-11 mm. 



Tyye (U.S.N.M. No. 49906), male, allotype, and four male para- 

 types, Bilby, Alberta, Canada, June 28, 1924 (O. Bryant). 



The quite striking resemblance of the sixth abdominal tergite of 

 the male of this species to that of normal females, although the 

 pygidium is not so well developed nor so extensive, readily dis- 

 tinguishes it from any other as yet known to me in the subfamily. 



PSEN (MIMESA) BOREAUS (Smith) 



Mimesa iorealis Smith, Catalogue of Hymenoptera in the British Museum, pt. 

 4, p. 431, 1856. (Male.) 



This species is very similar to pygidialis, but is much smaller, the 

 male has no raised lines on the apical tergite of the abdomen, the 

 female has the first tergite largely blackened at base, and the petiole 

 of the abdomen is shorter. The antennal flagellum of the male is 

 comparatively longer than in that species, with the sensory elevations 

 very slightly evident in profile, and pale. The propodeum is much 

 coarser sculptured, the enclosure having well-developed raised lines 



