318 - Mr.G.R. Waterhouse on some new genera and 
rounded ; the lateral keel is very distinct, acute, and remote 
from the lateral mar gins of the elytra. 
Legs moderate ; the anterior tibie but little compressed, and very 
little dilated at the extremity: they are provided with a short 
spine on the inner side at the apex, and the outer angle is 
somewhat prominent. Tarsi moderate as to thickness and 
rather long, those of the middle and hind legs being equal to 
the tibize in length, and those of the anterior pair of legs but 
little shorter than the tibie from which they spring: claws 
rather large. 
Presternum not produced posteriorly. 
This genus, to which I have given the name Platesthes in allu- 
lusion to its flat covering, the whole back of the insect being de- 
pressed and nearly on the same plane, evidently approaches closely 
to the genera Gyriosomus and Praocis, near to which should also 
be placed, in my opinion, the genus Physogaster. The last-men- 
tioned genus, M. Le Comte de Castelnau says, is closely allied to 
Pimelia ; but in making this assertion he must entirely have over- 
looked the structure and position of the labium, a part of the 
mouth which furnishes good characters for the sections of the 
Heteromera. On this subject I cannot enter at present, but I 
will merely remark, that in the Pimelide, Akiside, Tentyriide and 
Erodiide the labium is attached to the back part of the mentum 
in such a manner as to be totally hidden, or, at most, to leave ex- 
posed the points only of the paraglosse*; to these we may also 
add the Adesmia and Hpitragus group}. In the genus, the affi- 
nities of which I wish to determime, as well as the genera with 
which I have associated it, the labuatiy 3 is attached to the anterior 
extremity of the mentum, and is completely exposed and com- 
bined with a great similarity in the structure of other parts of 
the mouth ; they all have the throat-plate marked with the pecu- 
* The term paraglossz is applied by Kirby and Spence to the lateral lobes 
of the labium of the bees, and as the same parts exist in beetles, I think it 
well to call them by the same name; they lie for the most part behind the 
tongue, and are nearly always fringed with hairs in the Heteromera; but in 
the ‘latter groups (according to Dejean’ s arrangement of the order), Taxi - 
cornes and Tenebrionites, where the tongue is narrower, the outer margins 
of the paraglossze are distinctly exposed ; ; In some eases where the tongue is 
broad, as in Bolitophagus, the paraglosse are still very distinct (viewing the 
jabium from its outer surface), projecting as they do considerably in the 
lateral direction. 
+ Why should not these groups, in which the tongue is hidden, be asso- 
ciated together? We might commence with Epitragus, and continue 
through the other groups, Tentyriide, Erodiide, Adesmia, &c., where there 
is no separate emargination for the maxilla, and where the mentum covers 
that organ, to the Pimelide, Akiside and Nyctelide, where there is a sepa- 
rate notch in the throat-plate for the maxillee, which are exposed—at the base 
at least. 
