4 THE BRITISH WOODLICE. 
A small median plate attached to the front of the head has 
been called “the upper lip ” (fig. 9), while inside the mouth 
FIG: 5—THE MANDIBLES. 
‘Oniscus asellus.) 
FIG. 6.—THE FIRST MAXILLAE. 
(Ontscus asellus.) 
FIG, 7.—THE SECOND MAXILLAE, 
(Oniscus asellus.) 
appendages is a little bilobed structure 
“* the lower lip”? (fig. 10). 
Before leaving the external features 
of the head, we must allude to the 
pair of eyes which are usually present, 
though never raised on stalks, In 
the Common Wood-louse (Oniscus 
asellus, from which all our figures to 
illustrate structure have been made), 
as in many other species, the eyes are 
compound (fig. 4), but in some forms 
these are simple. 
Each of the seven joints of the 
thorax bears a pair of walking legs 
(fig.11), andin the female at the time 
when the eggs are laid, a pair of 
plates (fig. 12) arises on segments 
II. to V. These plates together 
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FIG. 8,—THE FUSED MAXILLIPEDS. 
(Oniscus asellus.) 
form a brood pouch, in which the eggs are carried (fig. 12) 
until they are hatched, and in which the young ones remain 
for some time afterwards. 
