Chap, xii.] NFRWUS SYSTEM OF CCELENTERATA. 395 



sene hair, which, acted on by movements in the 

 water, and communicating with the body of the cell, 

 is able to bring the animal into relation with the 

 outer world. 



In the sea-anemones the basal processes of the cells 

 have been observed to be continued into a layer of 



Fig. 167. Part of the submuscular plerus of Aurelia aurita, showing 

 gauglionic cells. (After Schafer.) 



fibres, whJT-h are to all appearance^ nervous in naiira x 



Well-developed ffganglionic cells are to be found 



scattered in the layer of nervous fibres which sur- 

 rounds the mouth. 



While in Aurelia and other Acraspedote Me- 

 dusse the central part of the nervous system consists 

 of isolator! ganglia^ ordinarily eight in number, the * 

 Craspedote Medusae, or those in which the edge 

 of the bell is provided with a vehim, have a more 

 definite central system ; the epithelial coverings of 



