106 Mr. Kirsy on Mr. W. S. MacLeay's 
rows*. When the mandibles are open, the food, after it has 
been divided by their apex, must pass between these plates, 
which, supposing that the ridges of one mandible are received 
by the furrows of the other, as is most probably the case, must 
have vast force in comminuting the food, not so much by the 
friction of the plates, since that could scarcely take place in 
consequence of the above structure, but from their pressure and 
the action of the sharp ridges. The mandibula indeed is parti- 
cularly fitted for this double office, the upper part being thin 
and adapted to cuttingt, and the base vastly thick and strong, 
as if its office was great pressure]. At the base of the mandible 
in the genus before us, but not in all, there are other short fur- 
rows forming an acute angle with the transverse ones and open- 
ing into the gullet. In the Dynastide MacLeay, the molary 
space is visible, but is smaller, and has fewer furrows. In Dy- 
nastes Enema it has only two obtuse ridges and as many furrows, 
and appears evidently calculated to masticate, but more grossly, 
a harder substance than what is submitted to the action of the 
mandibles of Melolontha F. In a specimen of Areoda I found 
adhering to this molary plate a substance resembling the pollen 
of flowers, which may hence be conjectured to be the food of 
that genus§. - 
From this account it seems I think evident, that a modification 
of the three kinds of teeth of vertebrate animals is to be found 
in these tribes as well as the Orthoptera, in which Marcelle de 
Serres detected them ; for we find the incisores at the apex of the 
mandible, the molares at its base, and the /aniarii at the apex of 
* TAB. III. Fig. 4. c; b. T Ibid. a. t Ibid. b. right hand figure. 
§ Since this paper was written, I met accidentally with a passage in Cuvier's Ana- 
tomie Comparée (iii. 391—.), by which it appears that he had observed in the mandibles 
of the larve of the Lucani “vers leur base, une surface molaire plane et striée ;? but he 
does not appear to have noticed this structure in any perfect insect. 
the 
