18 
POPULAR SCIENCE REVIEW. 
within the anterior margin of which is a minute organ divided 
at its anterior extremity into two lobes, fringed with hairs, 
PL II. fig. 16, very similar to, though much smaller than, the 
fringed lobes of the maxillae. These are the paraglossae. They 
are regarded by some authors as a second pair of maxillae ; and, 
like them, they bear at their base a pair of minute three- jointed 
palpi. 
The upper surface of the head is formed by a large rectan- 
gular piece, the fore part of which is called the clypeus, PI. II. 
fig. 1 c, somewhat produced at its anterior angles, where are 
situate the antennae, consisting of ten joints, the basal one being 
very long, and the remainder attached thereto at an angle, thus 
giving an elbowed character to these organs, distinctive of the 
family Lucanidae, to which the insect belongs. Of the remain- 
ing joints, the five terminal ones are formed into a pectinated 
club, somewhat resembling those of the Cockchafer, but not 
nearly so distinctly lamellated. The function of the antennae 
is the subject of considerable diversity of opinion amongst 
naturalists, some believing them to be organs of hearing, some 
of smell, and others again of a sense unknown to us. A large 
and conspicuous nerve enters the base of these organs. Em- 
bryological considerations have led to the conclusion that the 
four paired organs, viz. the antennae, the mandibles, the maxillae, 
and the paraglossae, are the limbs of so many segments of which 
the head is composed. The eyes are of the usual compound 
type ; they are small in comparison with the size of the insect, 
probably for the reason that its vegetable-feeding habits do 
not require its vision to be so keen or so widely extended in 
range as in carnivorous species. A small process of integu- 
ment called the canthus extends partly across the eye from its 
anterior border. This process is extended nearly or even quite 
across the eye in some of the burrowing Beetles, as in the com- 
mon Dung Beetle (Geotrupes). The structure of the compound 
eyes of insects has been so often described that it does not seem 
to require special comment here. The multiplication of similar 
parts in the eye of the insect, as compared with the single and 
highly-finished organ of the Yertebrates, may be taken as an 
evidence of inferiority of organization. Behind the clypeus, 
and extending forward laterally as far as the eye, is a piece 
called the epicranium, PI. II. fig. 1, e ; and on the under surface 
of the head behind the mentum there are two other portions of 
the integument, respectively termed the submentum, PL II. fig. 
2, sm, and the gula ; but the boundaries of these parts, though 
clear enough in some insects, are rather difficult to determine 
in the Stag Beetle. The hinder surface of the head, where it 
adjoins the prothorax, is perforated by a large orifice, allowing 
passage for the oesophagus, nervous cord, &c. ; and the portion 
