TIIE HEAD AND ITS APPENDAGES. 
11 
Setiform , or setaceous ; bristle-like ; long and slender, but tapering to- 
wards the tip. 
Moniliform, or bead-like; when the joints are about the same size, 
and round, so as to resemble a string of beads. 
Serrate , or saw-toothed ; when each joint is somewhat triangular, and 
a little prominent and pointed on the inner side. 
Pectinate , or comb-toothed ; when the inner angles of the joints are con- 
siderably prolonged. 
Bi-pectinate, or double comb-toothed ; pectinate on both sides. 
Glavate, or club-shaped ; gradually enlarging towards the tip. 
Capitate, or knobbed ; when a few of the terminal joints are abrubtly 
enlarged. 
Lamellate ; when the joints which compose the knob are prolonged on 
their inner side, in the form of plates. 
'Hie Eyes. — We have briefly described the mechanism of the eyes when 
treating of the sense of sight. They are uniformly of a round or oval 
shape, and sometimes notched on their inner side, to give place for the 
iusertion of the antennas. In a few instances they are placed at the end 
of foot stalks made by a lateral prolongation of the head. 
The Trophi, or parts ot the mouth. — The mouths of insects present 
two strongly marked variations, one of which is fitted for gnawing solid 
substances, and is called the mandibulate, or gnawing mouth ; and the 
other is fitted for sucking fluid nutriment, and is called the hamtellate, 
or suctorial mouth. 
Ihe mandibulate mouth is composed of six pieces, more or less dis- 
tinct, and their appendages. First, the labrum, or upper lip : a horny, 
usually somewhat semi-circular plate, attached to the anterior and infe- 
rior edge of the head, and serving to close and protect the mouth in front. 
Then v the Mandibles, or upper jaws; a pair of very hard, horny 
pieces, more or less hooked at the point, and often toothed on their in- 
ner sides, which work together laterally, somewhat like the blades of a 
pair of scissors. These are the true biting, gnawing, or masticating or- 
gans. 
Next are the Maxilla}, or lower jaws; a pair of organs, working lat- 
erally like the mandibles, but sotter and more pliable in their texture, 
generally divided into two lobes at their extremity, which are furnished 
moie or less with hairs. Ike maxilke undoubtedly' assist in the opera- 
tion ot eating, but the precise part which they perform is not well un- 
derstood. 
Behind the maxilke is a single piece which partially closes the mouth 
behind, and which may therefore be considered as the counterpart of 
the labrum or upper lip, and is accordingly called the labium, or lower lip, 
In the (Joleoptera this piece is usually attached at its base to the an- 
terior face of an elevated ridge upon the under side of the head, which 
