EARTHWOEM. 23 



II. Prepared longitudinal sections to show the re- 

 lations of cerebral ganglia, alimentary canal, 

 circumoesophageal commissure, and ventral 

 nerve-cord. 



1. Section through the median region (cerebral 



ganglia, alimentary canal, ventral nerve- 

 cord). 



2. Section at one side of the middle region 



(circumoesophageal commissure). 

 Diagrams in outline ! 



