648 A. MILNES MARSHALL. 



confining their attention too exclusively to one side of the 

 problems they attack, to the entire neglect of others, which are 

 not only of equal importance, but which would in many cases 

 yield them far more ready clues. 



Comparative physiology is a phrase which has become well- 

 nigh extinct ; but it is the name of a very real and very neces- 

 sary science, which only requires better opportunities for de- 

 velopment, such as we hope shortly to see forthcoming in this 

 country, in order to yield results of first-rate importance to 

 morphologists and physiologists alike. 



DESCRIPTION OP PLATE XXXV, 



Illustrating Prof. Marshall's Paper on '' The Nervous System 

 of Antedon rosaceus." 



The figures are diagrammatic, and are intended merely to show the position 

 and relations of the nervous system ; the other systems being omitted, either 

 wholly or in part. The nervous system is coloured black in all three figures. 

 In Figures 1 and 3, I have borrowed ideas from figures given by Ludwig 

 (' Morphologische Studien ') : all the figures are, however, constructed from 

 camera drawings of my own preparations, and the two mentioned will be found 

 to difi'er in some important points from the corresponding ones of Ludwig. 

 Aljihabetical List of References, 



«. Axial cord. b. Branches of axial cord. c. Branch of axial cord to 

 pinnule, d. Central capsule, e. Branches from central capsule to cirri. 

 /. Chambered organ, g. Central plexus, h. Subepithelial band (ambulacral 

 nerve), i. Ambulacral groove, k. Tentacle. I. Ambulacral canal, m. Sub- 

 tentacular canal, n. Cceliac canal, o. Pinnule, p. Cirri, r. Mouth, s. In- 

 testine, t. Ciliated openings in body-wall. u. Muscle. C. D. Centrodorsal 

 plate. B. Rosette. Ri. First Radial. R.. Second Radial. ^3. Third 

 Radial. Br^. First Brachial. Br^. Second Brachial. 



Fig. 1. — Diagrammatic vertical section through the disc and base of one of 

 the arms of Antedon rosaceus, showing the relations of the central cap- 

 sule, axial cords, and subepithelial bands. The section is interradial, i. e. 

 passes between two pairs of arms on the left side, radial on the right. 



Fig. 2. — Transverse section of an arm of Antedon rosaceus, passing 

 on the right side through 'the base of one of the pinnules. The figure is 

 diagrammatic as regards the branches of the axial cord, which are filled in 

 from a considerable number of sections. 



Fig. 3. — Diagrammatic plan of the central capsule and its branches in 

 Antedon rosaceus. 



