EXTERNAL ANATOMY OF INSECTS. 485 
laniary one?. The lower part of the inner or concave 
surface of the mandibles of grasshoppers will supply you 
with instances of the molary teeth, and the apex, also, of 
those of some weevils, as Cyphus Hancocki®. But the 
most remarkable example of a molary organ is exhibited 
by many of the Petalocerous beetles, especially those 
that feed upon vegetables, whether flower or leaf.— 
Knoch, who indeed was the first who proposed calling 
mandibles according to their teeth, incisive, laniary, or 
molary, but who does not explain his system clearly, 
observed that the mandibles of some Melolonthe have a 
projection with tranverse, deep furrows, resembling a 
file, for the purpose of bruising the leaves they feed 
upon®: and M. Cuvier, long after, observed that the 
larvee of the stag-beetle have towards their base a flat, 
striated, molary surface ; though he does not appear to 
have noticed it in any perfect insect’. This structure, 
with the exception of the Scarabeide and Cetoniade, 
seems to extend very generally through the above tribe; 
since it may be traced even in Geotrupes, the common 
dung-chafer, in which at the base of one mandible is a 
concave molary surface, and in the other a convex one, 
but without any furrows ; a circumstance that often distin- 
guishes those that have furrows.—In the Dynastid@ the 
* Prate VI. Fic. 12. and XIII. Fic. 5. b”. 
> Prare XXVI. Fie. 16. 
“ I was not aware that Knoch had observed this part, till some 
time after the publication of my paper On Mr. William MacLeay’s 
Doctrine of Affinity and Analogy (see Linn. Trans. xiv. 105—), when 
I happened to meet with it in a letter from a friend, received more 
than thirteen years ago; but without any reference to the work of 
Knoch, in which it was stated. It was doubtless taken from his 
Beitrage zur Insektengeschichte. 
4 Anat, Comp. iii. 321—., 
A ees 
