84 



THE COCKROACH 



which has six long rectal bands on its surface. The ileum, colon and rectum 

 represent the hind-gut or proctodseum. The anus opens beneath the 10th 

 tergum and between the podical plates. 



B. The Nervous System. 



Remove the epicranial plates of the head so as to expose the brain, which 



Cerebral ganglia 



/^^,,Optic nerve 



1 0^-.-Antennary nerve 

 M ■ r'-SuboESophageal 

 ganglion 



'7a 



-Prothoracic 

 ^ ganglion 



^^UU^ -Mesothoracic 

 '~2/li\^ ganglion 



Muscles -rr;-- 



• ^ — Metathoracic 

 ~^(l(^ ganglion* 

 ^"Ij^-.-lst Abdominal 

 ganglion 



6th Abdominal 

 ganglion 



Anal cerci. 



CEsophagus 



-Salivary gland 

 "Salivary reservoir 



Gizzard 



.■•Hepatic 

 C£eca 



Stomach 



Malpighian 

 tubules 



Anal styles 



Rectum 



Fig. 27.— The Cookroaoh {Periplaneta americana). A. Dissection of male showing the' alimentary 



system, etc. ; B. Nervous system. 



consists of two supra-oesophageal or cerebral ganglia incompletely divided by a 

 deep and narrow median fissure. The optic and antennary nerves are given off 

 to the eyes and the antennae respectively. The cerebral ganglia are connected 

 by the circum-oesophageal commissures to the sub-cesophageal ganglia lying in the 

 head immediately in front of the submentum. The sub-cesophageal ganglia supply 

 nerves to the mandibles, maxillae, and labium, and are joined by a long and 



