ON THE NERVOUS SYSTEM OF ANTEDON ROSACEUS. 



By A. Milnes Makshall, M.D., D.Sc, M.A., Fellow of St. John's 

 College, Cambridge ; Beyer Professor of Zoology in Owens College. 



[Plate XIV.] 



During a recent visit to the Zoological Station at Naples, I devoted 

 some time to an investigation of the nervous system of Antedon, 

 with the object of testing by actual experiment the validity of the 

 rival doctrines which have been advanced concerning it of late years. 



I propose in the present paper to give (1) a brief sketch of the 

 general organisation of Antedon, in order to define the terms employed, 

 and to make the following descriptions more readily intelligible; (2) a 

 short historical account of the controversy regarding the nervous 

 system of Antedon, including the present position of the question ; 

 (3) an account of my own experiments and observations ; and (4) a 

 discussion of certain points of morphological interest affected by the 

 conclusions arrived at in the preceding section. 



I. General Description op Antedon. 

 Antedon 1 consists of a central disc from which radiate five pairs of 

 long arms, fringed with pinnules. 



1 For fuller descriptions, wide Carpenter "Researches on the Structure, Physiology, and 

 Development of Antedon rosaceus," part i, 'Phil. Trans.,' 1866; and Ludwig, ' Morphologische 

 Studien an Echinodermen,' Bd. i, Abth. i ; and for a very excellent summary of recent re- 

 searches, vide P. H. Carpenter, "The Minute Anatomy of the Brachiate Echinoderms," 

 'Quart. Journ. Micr. Sc.,' vol. xxi. 



