14 INSECTA. 
gated cone; the intermediate joint of the club entirely enveloped by 
the two others, as in the last subgenera; the tibize narrow and elon- 
gated; the epistoma rounded anteriorly *. 
Acantuocerus, Mac Leay. 
First joint of the antennz very large, dilated superiorly and lami- 
niform; the edges of the intermediate leaflet of the club, when it is 
bent, are exposed. The tibize, the four last particularly, are lamel- 
liform and cover the tarsi, folding over them when the leg is con- 
tracted. The epistoma tapers to a point cr terminates in an angle. 
The thorax is almost semilunar + 
There, or in our second division of the Arenicoli— Trogides, Mac 
Leay—the antenne, scarcely longer than the head, are always com- 
posed of ten joints, the first of which is large and very hairy. The 
ligula is entirely concealed by the mentum. The labrum and man- 
dibles are but little exposed, and the latter are thick. ‘The palpi are 
short. ‘The mentum is entirely pilose. The inner side of the max- 
illee is armed with teeth. The cinereous or earth-coloured body is 
very scabrous or tuberculous above, The head is inclined, termi- 
nates In an angle or narrows toa point. The thorax is short, trans- 
versal, without a lateral border, sinuous posteriorly, with projecting 
anterior angles. The abdomen is large, arched, and covered with 
very hard elytra. The anterior legs advance, and their thighs cover 
the under part of the head. These Insects produce a stridulous noise 
by the reiterated and alternate rubbing of the pedicle of the meso- 
thorax against the internal parietes of the thoracic cavity. 
They are found in earth or sand, and appear to gnaw the roots of 
vegetables. They form the genus 
Trox, Fab., Oliv. 
From which, under the generic name of PHoprrus, M. Mac Leay, 
Jun., has separated those in which the sides of the thorax are de- 
pressed, dilated and bordered with spines, and which are destitute of 
wings. On each side of the posterior edge of the thorax is a deep 
emargination ; the epistoma is rounded anteriorly {. 
* Hor. Entom., I, 1, p. 120; Geotrupes orator, Fab. 
+ Mac Leay, Ib. p. 136; A. @naeus, a species for the knowledge of which I am 
indebted to one of ovr most able naval engineers, and not less excellent entomolo- 
gist, M. Lefebure de Cerisy. M. Mac Leay refers the Trox spinicornis, Fab., to the 
same genus. 
~ Trov horridus, Fab.; Mac Leay, Hor. Entom., I, 1, p. 137. The species of 
Trox, Fab., remain where they are. See this author, Olivier and Scheenherr. 
The genera Cryptodus and Mechidius, arranged by Mac Leay in his family of the 
Trogidz directly after that of PhoWrus, have the posterior extremity of the abdomen 
exposed, and nine joints in the antenn, characters which appear to remove them 
from Trox. I suspect that the Machidii, from the form and emargination of the 
labrum, and from some other characters, are allied to the Melolonthe. The Cryp- 
todi are distinguished from all other Scarabeides by their mentum, which almost 
completely covers the mouth beneath, and even by the labial palpi, situated, as well 
as the ligula, behind it. These two genera are established on Australian insects 
which I have not seen. 
._— 
