NERVOUS SYSTEM. 



295 



Moulting, which involves a casting of the cuticle, of the 

 internal lining of the tracheae, &c., occurs some seven times 

 before the cockroach attains in its fifth year to maturity. 



The muscles, which move the appendages, and produce 

 abdominal movements essential to respiration, are markedly 

 cross striped. 



Nervous System. A pair of supra-oesophageal or cerebral 

 ganglia lie united in the head. As a brain, they receive 



mx.p 



~S.ni 



FIG. 95. Mouth appendages of Cockroach. 

 DUFOUR.) 



(After 



I. Mn, Mandibles ; II. First Maxillae ; c, cardo ; st, stipes ; L, 

 lacinia ; G, galea; mx.p, maxillary palp; III. Second Maxillae or 

 Labium ; s.m, submentum ; m, mentum ; L, laciniae ; pg, para- 

 glossa ; l.p, labial palp. 



impressions by antennary and optic nerves. By means of a 

 paired commissure surrounding the gullet, they are connected 

 with a double ventral chain of ten ganglia. Of these, the 

 first or sub-cesophageal pair are large, and give off nerves to 

 the mouth parts, &c. ; from each of the ganglia of the 

 thorax and the abdomen nerves are given off to adjacent 

 parts. There are three pairs of ganglia in the thorax, and six 



