‘INTRODUCTION. 5 
distance from the antenne. Under the cornea, which varies in 
convexity, is found a transparent, rather hard, and nearly globular 
body, which is the true crystalline resting on a sort of lens, which 
- represents the vitreous body. This vitreous body is enclosed in an 
expansion of the optic nerve. Besides these, there is a pigment, 
most frequently red-brown, sometimes black, or blood-red. The 
organisation of these eyes is analogous to the eyes of fishes, and 
their refractive power is very great. 
With these eyes insects can ‘only see such objects as are at a 
short distance. Of what use then can stemmata be to insects also 
provided with compound eyes? It has been remarked that most 
insects haying this arrangement of eyes feed on the pollen of 
flowers, and it has been surmised that these stemmata enable them 
to distinguish the parts of the flowers. 
The antenne, commonly called horns, are two flexible appen- 
dages, of very variable form, which are joined to different parts of 
the head, and are always two in number. The joints of which 
they are made up have each the power of motion, and enable the 
insect to move them in any direction. 
The antennz consist of three parts: the basal joint, commonly 
distinguished by its form, length, and colour; the club formed by 
a gradual or sudden thickening of the terminal joints, of which 
the number, form, and size present great variations ; lastly, the 
stalk formed by all the joints of the 
antennz, except the basal one when 
no club exists, and in case of the 
existence of a club, of all those be- 
tween it and the basal one. 
We give as examples the anten- 
ne of two beetles, one of the genus 
Asida, the other of the genus Zygia 
(Figs. 3 and 4). 
Insects for the most part, while 
in repose, place their antenne on 
their backs, or along the sides of the Fig.3.—Antemaofa Fig. 4.— Antenna of 
species of Asida. Zygia oblonga. 
head, or even on the thorax. Others 
are provided with cavities in which the antenne repose either 
wholly or in part. 

