Mr. J. O. Westwood on the Lamellicorn Beetles. 155 
XXVI. On the Lamellicorn Beetles which possess exserted 
Mandibles and Labrum, and 10-jointed Antenne. By 
J. O. Westwoop, F.L.S., &c. 
[Read 3rd October, 1842, and completed 4th May, 1843.] 
Tue insects which form the subject of this paper, and which 
possess an exserted labrum, exposed mandibles and 10-jointed 
antennee, form portions of the families Trogide and Geotrupide 
of MacLeay. 
The former of these families, in the “ Horze Entomologice,” is 
distinguished from the other Saprophagous families as follows :— 
From the Scarabeide and Aphodiide by its exposed mandibles 
and labrum; from the Dynastide by its “ maxillz processubus 
duobus, interno dente arcuato corneo szepius instructo ; labrum dis- 
tinctum subquadratum et anus obvolutus;” and from the Geo- 
trupide by its corneous maxille. 
The antennez of the T’rogidc are described as ‘“ breves, novem 
vel decem articulis,”’ (p. 59,) in order to admit of the introduction 
of the Australian genera Cryptodus and Mechadius, (the first of 
which, as I have shown in previous papers read before the Ento- 
mological Society, belongs to the Phileurideous Dynastide, whilst 
Mechidius, as also shown by me in another paper, belongs to the 
Melolonthide,) as well as of the very interesting European genus 
AZgialia, which, in addition to its 9-jointed antennze, possesses a 
strong corneous hooked inner lobe to the maxille, with the outer 
lobe spinulo-setose.* 
This last named curious genus, therefore, justifies the admission 
of 9-jointed antennz into the characters of the family of the Trogide 
of MacLeay, namely, the genera Tox, Phoberus, and Acanthocerus, 
possessing 10-jointed antenne. All these genera, however, possess 
a character in respect to these organs by which they are distin- 
guished by Mr. MacLeay from the Geotrupide, (with which they 
agree in their exserted mandibles and labrum,) namely, the separa- 
tion of the three joints of the club of the antenne, whereas in the 
Geotrupide the two terminal joints are received into the cup-like 
basal joint of the club. The majority of the genera of Geotrupide 
possess 11-jointed antennee; Mr. MacLeay however adds to the 
family the genera Orphnus and Hybosorus, which possess 10-jointed 
* The insect figured by Guérin as the type of this genus, in the “ Iconographie 
du Reégne Animal,” 4g. cornifrons, possesses 10-jointed antennz, and forms the 
genus Geobius, Brullé (Hybalus), 
