424 Rev, W. Kirhy on Mr, Macleay's [Dec 



segment of the abdomen is not covered by the elytra ; but in 

 Mimela (a circumstance in which it agrees with Pciidnota Mac- 

 leay, another Soutli American type), only the tip is uncovered. 

 The latter, Mimela^ has an elevated prosternum, and a meta- 

 sternum with a very short anterior mucro, so as to leave the 

 mesosternum visible ; whereas in the former, Aveoda, the proster- 

 num is not visible without dissection, and the anterior mucro of 

 the metasternum is elongated so as entirely to cover and conceal 

 the mesosternum. The abdomen also in Areoda is covered 

 underneath with an infinity of very minute punctula, which give 

 it a silky appearance ; whereas in Mimela, and likewise Felid- 

 7iota, it is laevigated. 



Though Mimela agrees in most of its essential characters with 

 Euchlora, it differs sufficiently to form at least a subgemis in a 

 modern system. In the former the mandibulee have only two 

 teeth at their apex ; in the latter they have three. In this also 

 the body is covered with innumerable impressed puncta of the 

 same size ; whereas in that the puncta are of two sizes, the larger 

 scattered, the smaller almost invisible and quite covering the 

 surface. In Euchlora the last dorsal segment of the abdomen 

 and part of the last but one are uncovered, the very reverse of 

 which, as we have seen, takes place in Mimela. Whether the 

 inner claw of the four anterior legs is bifid at the apex in the 

 latter as it is in the former I cannot say, these tarsi being muti- 

 lated in my specimens. 



I shall here mention one very remarkable circumstance, no- 

 ticed by no writer that I have met with, which distinguishes the 

 mandibulae of the tribes of Melolontha F., though less conspicu- 

 ous in Melolontha itself than in the Euclora, Ihitelidcc, Anoplog- 

 uathid<r, Chalepus, Sec. The nwlary part, or that which appears 

 destined to comminute the food, is an orbicular or subquadrate 

 flat plate at the inner base of the mandibles, scored out into 

 numerous alternate transverse ridges and furrows. 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 comminut- 

 ing the food, not so much iDy 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 particularly fitted for this 

 double office, the upper part being thin and adapted to cutting, 

 and the base vastly thick and strong, as if its office was great 



Eressure. At the base of the mandible in the genus before us, 

 ut not in all, there are other short furrows forming an acute 

 angle with the transverse ones, and opening into the gullet. In 

 the Dt/nastida: Macleay, the molary space is visible, but is 

 smaller, and has fewer furrows. In Dynastes Enema it has only 

 two obtuse ridges, and as many furrows, and appears evidently 



