Genus Machidius of Mac Leay. 79 
short teeth at the inner margin, when seen obliquely ; beneath 
the middle of the mandible arises an elongated slender membrane, 
and the internal basal angles are much produced, but there is no 
transversely striated molary plate. The mentum and maxille 
closely unite to form the underside of the mouth, the lobes of the 
latter and the labrum not being produced more forward than the 
front margin of the mentum. The outer lobe of the maxille is 
horny and 5-toothed; the inner division of the maxillz is distinct, 
although small and horny; the inner lobe, arising from its extre- 
mity, small, membranous and ciliated. The mentum has the sides 
straight, but not parallel, the front margin being wider than the 
base, and almost straight; the labial palpi arise within, close 
to the anterior angles of the mentum, the tip of the second joint, 
and the short third joint, being only visible. Within the mouth, 
between the mandibles and the supposed labrum, I observed, in 
two specimens I dissected, a membranous piece which appears to 
me to be analogous to the membranous labrum of the Scarabeide. 
The two spurs of the middle tibize are acute, but the two at the 
extremity of the hind tibize are obtuse and flat; the fore tibize are 
obtusely tridentate on the outer margin, and the outer extremity 
of the two posterior tibiae is produced into a thick diverging spur ; 
all the ungues are simple and entire. 
On reviewing these characters with reference to the group to 
which the genus naturally belongs, I see no grounds for regarding 
it as Trogideous, whilst its relation to the Melolonthide appears far 
stronger. This is more especially the case if Mr. Mac Leay be 
correct in the nomenclature of the part he terms labrum. It may 
appear strange that any doubt can exist as to whether a Lamelli- 
corn beetle is Thalerophagous or Saprophagous ;* but the fact is, 
* By comparing the characters of Mechidius with those of these two groups, 
as given by Mac Leay (Hore Ent. i. pp. 68, 69) we shall perceive that the genus 
accords even better with the Thalerophaga than with the Saprophaga. 
SAPROPHAGA, Mecuintvs. THALEROPHAGA. 
Antenne 8- to 11-jointed, Antenne 9-jointed. Antenne 9- to 10-jointed. 
Clava short, thick, 3- Clava rather elongate, Clava rather elongate, often 
jointed. 3-jointed. more than 3-jointed. 
Feet always robust. Feet rather slender Feet less robust. 
Tibiz broad. Tibiz narrow. Tibia rather narrow. 
Ungues undivided. Ungues undivided. Ungues often divided. 
Colour lurid or black. Colour lurid. Colour gay metallic. 
Elytra generally extend- Elytra not covering the Elytra rarely covering the 
ing to the anus. anus. anus. 
I omit the nature of the food, because we are ignorant of that of Mechidius. 
