192 CRABRONIDA. 
whitish ; the wings iridescent, hyaline, but darkish towards their 
apical margin; the legs black, with the knees of the anterior 
femora, their tibiae and tarsi, the base and apex of the inter- 
mediate tibize and their tarsi entirely, and the base and apex of 
the posterior tibiae, fulvous. 
The abdomen black, with the margins of the first three seg- 
ments constricted, especially the back of the two first 9. 
The g differs by the obsolete or deficient tubercle of the 
face, the latter, as well as the clypeus, has a silvery pubescence ; 
the scape of the antennz entirely black; the anterior tibiz in 
front merely, and the other portions of the legs, which in the 9 
are fulvous, here are luteous, excepting the apex of the posterior 
tibie, which is black. 
g @ in my own Collection. 
+4+ The marked differences of these three insects war- 
rant my considering them as distinct species, especially as 
my opinion is formed from a great number, which all agree. 
It is remarkable, that the horn in the centre of the face is 
found only, and that very conspicuously, in the ¢ of the in- 
signis ; in the ¢ it is not present, nor in either of the sexes 
of the gracilis; but in the ¢ of corniger it is again very 
prominent, and only obsoletely present in the $. What 
can be its use? It is evidently not a sexual character, as 
the first and the last of these species have it in the opposite 
sexes ; and we find a somewhat similar appendage in both 
sexes of the Pemphredon (Ceratophorus) morio. I have 
hitherto detected nothing in its economy which at all leads 
even toa supposition. The species is not uncommon in 
Battersea Fields, where I have captured it upon a currant- 
bush infested by an Aphis. 
Genus XXVI.—Pempurepon. Latr. 
Heap large, subquadrate; eyes small, ovate, placed at the 
lateral angles of the head; the stemmata in a triangle on the 
