BLATTA. 223 
confinement upon bread. The body is plano-symmetric, 
and is encased in a hard exoskeleton. This consists of 
a chitinous cuticle secreted by the ectoderm, but it differs 
Int from that of the lobster in the absence of 
egu- zi 
saan calcareous matter. Hence the exo-skeleton Is 
¥ tough and somewhat flexible, but not nearly 
so hard and thick as that of the latter. We can still 
Fig. 148.—THE Common Cocxroacu (Blatta Orientalis ). 
Natural Size. 
A, Male with wings expanded ; B, Female with vestigial wings ; C, Wingless young. 
distinguish chitinous sclerites united by softer arthrodial 
membranes. 
The body is divided into three parts—the head, the thorax 
and the abdomen. Of these the head is not segmented, the 
‘thorax is partially so, but the abdomen is as 
estate’ clearly segmented as in the lobster. The head 
‘ bears one pair of long antenmne@ at the anterior 
end, and close to them is a pair of compound eyes, not 
External 
