NEKVOUS SYSTEM OF ANTEDON ROSACE US. 539 



sudden folding of the pinnules alongside the irritated spot. 

 The ambulacral grooves are structures of great importance to 

 the animalj for it is by them that food particles are captured 

 and swept along by the ciliary currents to the mouth. 

 Furthermore, the subepithelial band is in very intimate re- 

 lation with that most characteristic Echinoderm system, the 

 ambulacral vessels and their prolongations forming the ten- 

 tacles. 



Seeing, then, that there are along the ventral surface of the 

 arms structures of great importance in very close anatomical 

 relation with these subepithelial bands, which agree histologi- 

 cally with what are undoubtedly nerves, it seems probable that 

 these bands form a special part of the nervous system con- 

 nected with one or other, or perhaps all of these special 

 structures. 



That the connection between the subepithelial bands and 

 the ambulacral epithelium and tentacles is a very intimate one 

 is shown by P. H. Carpenter's observation, alluded to above, 

 that in both Antedon and Actinometra all three structures dis- 

 appear together, both in the oral pinnules and in those arms 

 or portions of arms which are devoid of ambulacral grooves. 



G. Summary of Results. 



1. The central capsule and its prolongations, the axial cords 

 and their branches, constitute the main nervous system of 

 Antedon. 



2. The central capsule is specially connected with the com- 

 plex co-ordinated movements of swimming and of righting 

 Avhen inverted. 



3. The axial cords act as both afferent and efferent nerves. 



4. The subepithelial bands are probably also nerves, but 

 their exact function, probably a special and subordinate one in 

 connection with the ambulacral tentacles and epithelium, is 

 not yet ascertained. 



5. Evisceration apparently causes but little inconvenience to 

 the animal, and the visceral mass is regenerated completely in 

 a few weeks' time. 



