1941] 
A New Stizus from Utah 
175 
of the cavelike hollows characteristic of the red sandstone 
of this region. In the early morning, over the steep talus 
slope to one side of this ‘cave/ still in the shadow of the high 
cliff on the east, great numbers of these wasps were circling 
and darting about. In their erratic flight they would scarce- 
ly ever pause, and it was only after considerable effort that 
I finally secured three specimens. They did not appear at 
all wary and had it not been for the very insecure nature of 
the steep slope and loose rocks, they would have been taken 
quite easily. The wasps soon disappeared, long before any 
sunshine reached the spot. There was practically no vege- 
tation on the slope where the wasps were observed.” 
Remarks. — The present species of Stizus is the fourth of 
the genus (as now restricted) to be described from North 
America. Of the remaining three it is most closely related 
to occidentalis Parker, a member of the ruficornis group. 
The male of the new species, like that of occidentalis, has the 
first transverse cubital vein practically straight, not evenly 
curved toward the apex of the wing. If the female should 
prove to have a scutellar pit (as it does in occidentalis ) , 
iridis may be assigned to the ruficornis group without 
question. 
The types of iridis have been compared with the holotype 
male of occidentalis , which differs in the following struc- 
tural details. In the holotype of occidentalis the clypeus is 
evenly convex in profile; it has a wider emargination an- 
teriorly and the posterior margin is practically straight 
(fig. 2) . Lateral to each posterior ocellus of the holotype of 
occidentalis, there is a longitudinal shining impression, 
about one-third the diameter of the ocellus in width ; it ex- 
tends posteriorly for a distance about equal to the diameter 
of the ocellus, but does not descend the vertical face of the 
occiput. Behind the anterior ocellus there is no circular 
impression. Linear tyloids are present on antennal seg- 
ments 7-13, instead of 6-13 as in iridis; on the right antenna 
they are all conspicuous, but on the left less so, particularly 
on 7 and 8. In dorsal aspect the thorax appears more 
rounded anteriorly, and more pointed behind. The parap- 
sidal furrows are represented by simple impressed lines. 
The posterior angles of the propodeum are less convex than 
in iridis, and the sutures defining the propodeal area are not 
