(\, & 
the thorax (Ammophila, Cerceris), occasionally subglobose, 
(Methoca, Tiphia), or large and subquadrate (Crabro, Pem- 
phredon, &c.), rarely triangular (Crabro vewxillatus, male), 
and as rarely armed with a spine beneath the cheek (Cra- 
bro subpunctatus, &c.), or with an acute one in the middle 
of the face between the base of the antennee (Xylacus cor- 
niculus); sometimes a longitudinal (Cerceris) or triedral (Psen 
atratus) carina in the same situation; or a tubercle to which 
the antenne are laterally attached (Dolichurus). The ryEs 
are generally oval, sometimes subglobose, frequently pro- 
minent, very rarely contiguous (Astata, male), the canthus 
occasionally entering deeply, giving them a kidney shape 
(Sapyga, Trypoxylon). The stemmata are placed upon the 
vertex generally in a triangle, which is sometimes very 
open, forming only a slight curve;* the posterior pair are 
nearly confluent or obsolete in Larraand Tachytes, and they 
are deficient in the female Mutilla. The antENN# inva- 
riably consist of thirteen joints in the male, and twelve in 
the female.+ The bulbus or radicle has been, by mistake, 
* This is one of those anomalies of structure for which, unless it be to con- 
stitute a specific distinction, to which it admirably subserves, I cannot ac- 
count; it is most remarkable in the black species of the genus Crabro. 
+ St. Fargeau, at p. 693 of the Third Volume of the Annales de la Societé 
Entomologique de France, doubts this as being general in the aculeate Hyme- 
noptera, and instances Ceramius (which I suppose he intends for Celonites) and 
Masaris, as having fewer, but all the three genera have decidedly those numbers, 
which I know positively from ocular demonstration. Mr. Hope’s rich cabinet 
possesses a specimen of the rare genus Masaris, which I have had the oppor- 
tunity of inspecting, and in my own collection I possess the others. I should not 
here have made this reference to foreign insects, had not St. Fargeau cited 
them to support his opinion that some male Crubros have but twelve, which I 
can assure him, if he will use a lens of a high power, he will find to be a mis- 
take. I was in doubt myself, until I inspected them in a flexible state, or in 
recent insects, the two first joints of the clavolet being very closely connected 
