24 
THE HEAD OF THE BEE. 
vexity being greatest in the jaws of the worker, less so 
in the queen, whereas in the drone it is hardly notice- 
able. The drone has the outside covered with hairs, 
which are much less numerous in those of the queen 
and worker, whose jaws, however, have a row of 
hairs on the inside (Fig. 51, b). 
In describing the remaining mouth parts, we give 
the investigations of Dr. O. J. B. Wolff (170), which 
he published in 1874, and also of V. T. Chambers 
(23) in 1878, and J. D. Hyatt (70) in 1879, and 
T. J. Briant (12) in 1884, which clear up a great 
many of the hitherto obscure points. 
The labium^ or under lip, which forms the main stem 
of the rest, is composed of several parts. The strongly 
chitinous mentu 77 i (Fig. 10, a) lies at the upper ex- 
tremity towards the back of the head, is joined to it 
by means of the sub 77 ie 7 itu 77 i.^ or triangular fulcru 77 i of 
Kirby (Fig. 10, ^), which is connected to the cardi 7 tes 
(Fig. 10, c c) by the lora (Fig. 10, d ^), and is ex- 
tensible and contractile at the will of the insect. 
The mentum contains the muscles, which can 
draw the ligula (Fig. 10, e) partly into it. The labium 
is soft at the top and hard at the sides and under- 
neath. It forms a knee-bend at part of its length. 
The labial palpi (Fig. 10, g f) are attached to the 
mentum on either side by a hinge-joint. They con- 
sist of four joints, the two at the extremities (Fig. 10, 
yj /) being very small, and are furnished with tactile 
hairs (Fig. ii, a), and have a number of transparent 
dots, described by Dr. J. Hicks (65) in i860. 
On either side of the labial palpi, and fastened to 
