11 (10). 
12 (9). 
the classification of British Crabronidae. 393 
Head in front of the anterior ocellus with the surface on 
each side of the median impression not at all depressed 
but slightly convex, and not polished, finely punctured. 
Bb. pubescens, Shuck. 
Head above and mesonotum with short and much less 
conspicuous hairs; mesosternum polished, finely and 
remotely punctured, very deeply excavated posteriorly ; 
tubercles of the mesopectus very feebly developed. 
B. (?) cetratus, Shuck. 
. Mandibles at the apex with four teeth, the innermost the 
smallest; mesopectus not spinose; superorbital foveae 
more or less feeble and shallow. 
. Hind tibiae unarmed, not spinose above; clypeus produced 
in the middle into a strong, blunt, narrow, apical tooth 
or process, and with a smaller and shorter tooth on each 
sideofthis ... 9. -s '. 2 ‘Bi (?) capitosus, Shuck. 
. Hind tibiae armed with spines; clypeus not produced into 
a strong narrow median tooth, but faintly 3-dentate or 
3-tuberculate . . Wh 2. SBS )atgrivs, Kohl. 
7). Anterior area of erbhodleudh detined by a distinct consute, 
or crenate furrow, usually complete, very rarely a little 
incomplete. 
2). Mandibles either bidentate or tridentate at the apex (the 
teeth sometimes worn down or blunt); occipital margin 
beneath the head not produced into a prominent spine 
or angle at its apical extremity. 
. Small species, with black (not yellow-marked) abdomen; 
superorbital foveae small or feeble or marked only by 
smooth spaces or faint impressions. 
)). Pygidial area with the sides strongly raised so that it 
appears excavated. 
). Mandibles tridentate. 
. Mesopectus not spinose or tuberculate on each side, 
. Clypeus with a distinct prominent tooth on each side of 
the middle of the apical margin; clypeus black. 
B. (2) gonager, Lep. 
. Clypeus somewhat broadly rounded or nearly truncate in 
the middle of the apical margin; clypeus wholly or largely 
yellow Bilt 3 >. « 's) B. (2) aphidum, Lep. 
. Mesopectus gibéoulide or spinose on each side. 
B. (?) carbonarius, Dahlb. 
* I have not been able to examine the mandibles of this species. 
and its position here is doubtful, 
