VII 



PHYLUM ECHINODERMATA 



175 



movements propelling it slowly through the water. Tube- 

 feet are not developed as such ; but are represented by a 

 great number of very minute simple processes, the tentacles, 





which border grooves running along the upper surfaces of 

 the arms and of the pinnules. 



Some of the Crinoidea, the stalked Crinoids (Fig. 93), chiefly 

 occurring at great depths in the sea, are supported on a long 



