BLATTA. 



223 



confinement upon bread. The body is piano-symmetric, 



and is encased in a hard exoskeleton. This consists of 



a chitinous cuticle secreted by the ectoderm, but it differs 



from that of the lobster in the absence of 



calcareous matter. Hence the exo-skeleton is 



men ary. ^^^^ ^^^ somewhat flexible, but not nearly 



so hard and thick as that of the latter. We can still 



Fig. 148. — The Common Cockroach (Blatta Orientalis). 



Natural Size. 



A, Male with wings expanded ; B, Female with vestigial wings ; C, Wingless young. 



distinguish chitinous sclerites united by softer arthrodial 



me?nbranes. 



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 

 clearly segmented as in the lobster. The head 



External 

 Features. 



bears one pair of long antennce at the anterior 

 end, and close to them is a pair of compound eyes, not 



