282 CRABRONID&. 
the wings very slightly coloured, iridescent, the nervures black ; 
the legs black; the apical joints of the tarsi piceous, the an- 
terior tarsi slightly ciliated, and the intermediate and posterior 
tibize spinose. 
The abdomen shining, delicately punctured, covered with a 
sericeous pubescence; the petiole about the length or a little 
longer than the remainder of the first segment, and carinated 
above, the carina acuminate at its apex, and sometimes bifid 
at its base, or obliquely striated, the hypopygium slightly pro- 
duced 9. 
The ¢ differs in having more of the silvery pubescence on 
the face; the antennz longer and slighter, and the anterior and 
intermediate tarsi testaceous, and the posterior ferruginous, or 
all ferruginous, and the hypopygium produced into an up- 
curved pale spine. 
+4} I think it is very probable that this is the Psen 
ater of Latreille ; but he having given no satisfactory de- 
scription of it, it is very uncertain. I have found it at 
Darenth Wood in Kent, and Mr. Walker has taken it in 
North Wales, inhabiting posts and rails. 
2. The clypeus trilobate. The abdomen not constricted at 
its base into a long and slender petiole. 
Genus XXXIV.—Cerceris. Latr. 
Heap subquadrate, transverse, wider than the thorax; the face 
vertical; the eyes ovate, placed at the lateral angles of the 
head ; the stemmata slightly elevated on the vertex; the an- 
tenne subclavate, inserted near the middle of the face on 
each side of a carina, which runs from the centre of the face 
to the base of the clypeus, the middle lobe of which it em- 
braces ; the clypeus trilobate, the central lobe the largest, and 
having anteriorly a narrow margin; labrum concealed; the 
mandibles very stout, tridentate, the apical tooth acuminate, 
