COCKROACH. 



291 



The 



young are 



Fig. 127. — Leg of cockroach. 



, Broad expanded coxa; tr., troch- 

 anter ;yC, femur ; //., tibia; ta., five- 

 jointed tarsus with terminal claws and 

 adhesive cushions. 



same order as locusts and grasshoppers, 

 hatched as miniature adults, 

 except that wings are absent ; 

 in other words, there is no 

 metamorphosis in develop- 

 ment. 



Skin. — There is an exter- 

 nal chitinous cuticle and a 

 subjacent cellular layer — the 

 epidermis or hypodermis — 

 from which the cuticle is 

 formed. The newly hatched 

 cockroaches are white, the 

 adults are dark brown. 



Moulting, which involves a 

 casting of the cuticle, of the 



internal lining of the tracheae, etc., occurs some seven times 

 before the cockroach attains in its fifth year to maturity. 



The muscles which 

 move the appendages, 

 and produce the abdo- 

 minal movements essen- 

 tial to respiration, are 

 markedly cross striped. 

 Nervous system. — A 

 pair of supra-cesopha- 

 geal or cerebral ganglia 

 lie united in the head. 

 As a brain they receive 

 impressions by anten- 

 nary and optic nerves. 

 By means of a paired 

 commissure surround- 

 ing the gullet, they are 

 connected with a 

 double ventral chain of 

 ten ganglia. Of these, 

 the first or sub-cesopha- 

 geal pair are large, and 

 give off nerves to the mouth parts, etc. ; from each of the 

 ganglia of the thorax and the abdomen nerves are given off 



mx.p 



-S. 



Ill 



Fig. 128. — Mouth appendages of cock- 

 roach. — After Dufour. 



I. Mil., mandibles ; II. first maxilte ; C, cardo ; 

 St, stipes ; L., lacinia ; G., galea; mx.p., 

 maxillary palp ; III. second maxillae or la- 

 bium ; S.?u., submentum ; 111., mentum ; L., 

 lacinise ; pg. paraglossa ; l.f>., labial palp. 



