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XXVIII. Descriptions of some new Species of Athyreus, a Genus of Lamelli- 
corn Beetles. By J. O. Westwoop, Esq., F.L.S. &c. 
Read February Ist, 1848. 
THE genus Athyreus was first proposed by Mr. W. S. MacLeay, in the 
appendix to the * Horae Entomologice, for the reception of three Brazilian 
species, A. bifurcatus, tridentatus and bidentatus, and was placed in the family 
. Geotrupide, with the remark (p. 53), that * by way of proof that the Geotru- 
pide are principally confined to temperate climates, I may observe that the 
. tropical insects of this family principally belong to the extreme genera, such 
as Athyreus and Hybosorus, the former of which approaches to the Scara- 
beide and the latter to the Dynastide ;” the relation of Athyreus to the 
Scarabeide being again alluded to in p. 123, in the observation, “ Genus 
admodum singulare, capite neglecto a Copride haud distinguendum, sed ab 
Elephastomo quoque haud longé distat." 
The characters of the genus as laid down by Mr. MacLeay do not however 
give a clear idea of its peculiarities; neither are the species, which he has too 
briefly defined, to be identified with proper precision. The mandibles (Tas. 
XXII. fig. a, a), for instance, instead of being flat on the upper surface are 
quite concave, the lateral and apical portions not being covered by the labrum; 
and as each is of a different shape, a single description will not apply to 
them. I have given a delineation of them in the accompanying figures, and 
must here only allude to the black, horny, flattened molar plate at the base 
on the inside, which is destitute of those curious transverse ridges which are 
seen in the Melolonthide ; this peculiarity being an important one, bearing 
directly upon the nature of the food of the insects, which is ground by these 
two hard parts of the mandibles being brought together by the action of the 
strong muscles inserted near the outer base of the jaws, close to the deep 
notch which will be seen near the small ball that fits into the socket of the 
head where they are attached. 
