ARTHROPODA. 21 



and extend forwards as far as the anterior fifth of the body. 

 Each end of each vesicle communicates by a duct with a 

 minute common longitudinal canal. There would thus be 

 twenty pairs of ducts passing from the testes to the central 

 canal. Posteriorly this canal becomes of considerable size, and 

 is disposed in spiral coils before it reaches its external opening. 

 Beneath it, and in the last two segments of the body, are 

 seen the 'accessory glands.' The long dorsal vessel has been 

 pinned on the left of the specimen. 



32. A Centipede (Scolopendra), dissected to shew its 

 nervous system. 



It has been laid open along its ventral surface. A black 

 bristle indicates the position of the oesophagus. 



The nerve-system consists of a double cord placed medially 

 in the body. The cephalic ganglion supplies the antennas and 

 eyes. Posteriorly to this the cords divide to admit of the 

 passage of the oesophagus. Subsequently there are ganglia 

 at regular intervals, corresponding in number to the segments 

 of the body. From each nerves are given off to supply the 

 legs. The first ganglion is oval in form, the- others are round. 



Class INSECTA. 



1. Order Coleoptera. 



33. A Goliath Beetle ( Cetonia cacicus), disarticulated and 

 mounted on wires to shew its segments- and their appendages. 



34. Digestive system of an Oil-Beetle (Meloe proscarabceus). 

 Nearly the whole of the exoskeleton, together with the 



other organs, has been removed. 



The oesophagus, which is very short, leads into a large 

 elongated oval stomach, occupying the greater part of the ab- 

 dominal cavity. On, leaving the stomach the intestine becomes 

 suddenly extremely narrow, and is slightly convoluted. Its 

 terminal segment is dilated into a rectum. 



Near the posterior end of the stomach the hepatic vessels, a 

 number of thread-like caBcal tubules, may be seen. 



35. A Stag Beetle (Lucanus cervus), dissected to shew its 

 nervous system. 



