i 
170 Transactions of the Boyal Society of South Africa. 
mously distended. The sexual differences consist in the males being 
usually smaller than the females, and in the apical abdominal segment of 
the former being more or less deeply incised, while it is entire in the 
latter ; but in certain species the intermediate antennal joints are nodose 
or greatly enlarged in the male. 
Gen. MELOE, Linn., 
Syst. Nat., 10th ed., 1758, p. 419. 
Mentum (pi. xxii., fig. 3) transverse, sub-angular laterally and sinuate 
near the margin ; ligula also transverse, arcuate, ciliate along the anterior 
margin, labial palps robust, thick, the ultimate triangularly dilated, almost 
truncate at apex ; maxillae (pi. xxii., fig. 3a) also robust, both the inner and 
upper lobes dilated and densely ciliate, pubescent at apex ; maxillary 
palps moderately long and of the same shape as the labial ; labrum trans- 
verse, either emarginate at apex or not ; mandibles robust, more or less 
hidden by the labrum ; head longer than broad, with the transverse 
epistome greatly narrowed, eyes only moderately large ; antennae variable 
in shape and length, the second basal joint always much smaller than the 
third, the last one longer than any of the preceding ones, sub-arcuate 
outwardly, straight inwardly and sharp at tip ; prothorax of variable shape 
(pi. xxii., figs. 3, 4) ; scutellum atrophied; elytra very short, strongly divari- 
cating from or near the scutellary region, much shorter than the abdomen ; 
wings absent ; legs moderately long or long, tarsi as long as the tibiae or 
longer ; outer spur of hind tibiae thick, obliquely truncate outwardly, or 
sub-lanceolate and excavated, inner spur slender and sharp ; upper part of 
claw not pectinate, lower very slender. 
The abortion of the wings, the great divarication of the elytra, and the 
extremely large abdomen impart to the insects belonging to this genus a 
facies of their own. When seized they exude through the joints of the 
legs, especially the knees, a yellow fluid, much in the same manner as in 
the genus Horia. Ifc is this peculiarity which has gained for them the 
popular name of " oil beetles." 
Four species are recorded from Central Africa, but none from Sene- 
gambia, where, however, the genus is probably represented. 
Key to the Species. 
A^. Antennae barely reaching the posterior angle of the prothorax. 
B^. Prothorax with a median longitudinal groove and no transverse 
impression along the base. 
a^. Body black. , 
Prothorax very roughly scrobiculate, as broad as long and 
sharply angular laterally in front ; elytra finely plicate-wavy 
longitudinally angulatus. 
