NERVOUS SYSTEM. 95 



ciliated cells (Endoderm), and externally by 

 the coenosarcal layer (Ectoderm), which also 

 lines the body cavity. There appears to be 

 also an intermediate layer of a muscular 

 character. 



Nervous system. The nervous system 

 is represented by a single or bi-lobed ganglion 

 (collection of nerve-cells), situated on the wall 

 of the oesophagus, within the body cavity, and 

 upon the anal side. It sends out nerves to 

 the tentacular crown, oesophagus, reproductory 

 organs, and elsewhere. 



Muscles. The chief muscles are the 

 Retractor muscles for withdrawing the mouth 

 and tentacles within the sheath ; the muscles 

 connecting the stomach with the body-wall 

 (Gastric muscles); the muscles connecting the 

 base of the stomach with the body-wall 

 and termed the Funiculus. Lastly, the 

 muscles which line the body-wall, (Parietal 

 muscles), used for reducing the capacity of 

 the body cavity and thus everting the mouth 

 and tentacles. The muscles are of a very 

 rudimentary character, being single and 

 barred, and when relaxed hang loosely like 

 threads of cotton. 



