396 Mr. R. C. L. Perkins on the British Crabronidae. 
arched beneath. Clypeus very strongly produced in the 
middle, with an angle on each side of the median produc- 
tion. Front and middle metatarsi abnormal, though not 
greatly dilated; apex of occipital margin beneath the head 
produced into a spine as in Hoplocrabro; a median frontal 
prominence between the antennae. 
Rhopalum, Kirby, R. tibiale, Lep. 
2 (1). Antennae nearly simple, the 6th joint with a slight emar- 
gination or arch beneath; clypeus and face ordinary ; 
metatarsi simple . Physoscelis, Lep., P. clavipes, Linn. 
Le 
1 (2). Clypeus strongly produced in the middle and with distinct 
lateral angles; face with a mediofrontal prominence; 
pygidial area apically produced and excavated; hind 
tibiae conspicuously spinous above. 
Rhopalum, K., R. tibiale, Lep. 
. Clypeus ordinary ; pygidial area dull, with dense microscopic 
granulation, its margins very feeble, hardly produced 
apically, not excavated; face simple; hind tibiae incon- 
spicuously spinose . . Physoscelis, Lep., P. clavipes, L.* 
bo 
— 
— 
~— 
LINDENTINAE. 
1 (4). Eyes bare; mandibles simple . . . . Lindenius, Lep. 
(3). ¢ hind tibiae yellow above; 9 hind tibiae yellow only at 
the base, usually for about one-fourth of their length. 
L. albilabris, Fab. 
3 (2). ¢ hind tibiae yellow on the basal half only or less; 9 hind 
tibiae yellow except at the apex. L. panzeri, V. d. Lind. 
4 (1). Eyes hairy; mandibles with a prominent angle near the 
base beneath. 
Entomognathus, Dahlb., HE. brevis, V. d. Lind. 
* Since the above was written a second species of Rhopalwm has 
been added to our list by Col. C. G. Nurse (Ent. Mo. Mag. 1913, 
p. 83). It may be distinguished as follows : 
a. Clypeus in the middle triangular (rounded in 3 at apex, 
acute in 9), tegulae pale. il ys R. tibiale, Lep. 
b. Clypeus in the middle truncate, tegulae black; abdomen 
wholly black. 3 ot ee Hea hiesenwetteri, Mor, 
