NERVOUS SYSTEM OF ANTEDON ROSA.OEUS. 507 



On the Nervous System of Antedon rosaceus. 



By 



A. mines marsliall, Itl.D., D.Sc, M.A,, 



Fellow of St. Johu's College, Cambridge ; Beyer Professor of Zoology ia 

 Owens College, Manchester. 



With Plate XXXV. 



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 con- 

 troversy 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 con- 

 clusions arrived at in the preceding section. 



I. General Description of Antedon. 



Antedon^ consists of a central disc from which radiate five 

 pairs of long arms, fringed with pinnules. 



^ For fuller descriptions, vide 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 ; 



