32 W. PERCY SLADEN. 



the same order of development may also be traced, to a certain 

 extent, in the earlier works of jMiiller^ and Metschnikoff.^ 



The plates which I have considered to be first radials (fig. 

 15 ; 4, 4), are called '' intermediate plates " by Ludwig,^ as he 

 considers the terminal plate homologous with the first radial of 

 a Crinoid ; and it will be seen that I also differ from my friend 

 Carpenter in the lettering of his fig. 4 in his last paper^ No. 5, 

 of Notes on Echinoderm Morphology.* In this Carpenter had 

 followed Ludwig, and it is not difficult to undertand how such 

 a misconception of this plate, th.e radial, should have arisen 

 when only the very early phases of the larva are taken into 

 consideration, without reference to those of fuller growth. 

 Carpenter has candidly admitted the justice of my view and 

 has given expression to the same opinion in his accompanying 

 paper (ante, p. 3). 



Having now briefly discussed the homologies of the plates in 

 the larvjB of well known species, which have been carefully 

 observed by previous writers, I would direct attention to an 

 interesting deep-water Starfish which afi'ords a striking confir- 

 mation of the views I have expressed ; and it is further impor- 

 tant to note that in this case, the plates of which we have been 

 treating maintain their distinctness and character throughout 

 life, and do not become concealed or masked in the adult stage, 

 as happens in the forms we have been considering. Of the 

 Starfish in question, Zoroaster fulgens, Wyv. Thomson, I 

 have had the opportunity of studying a series of specimens in 

 various stages of growth, obtained by the '' Porcupine " Expe- 

 dition, and more recently by Mr. John Murray during the 

 cruise of H.M.S. "Triton''^ in the Faeroe Channel. The 

 young Zoroaster fulgens has a very remarkable appearance 

 owing to the prominence and distinctness of the component 



1 ' TJeb. die Larven u. die Metamorphose der Echinodermen,' Abiiandl. iv 

 (1852). 



2 " Studien ueb. die Entwickelung der Echinodermen u. Nemertineu," 

 ' Mem. Acad. St. Petersb.'/ T. xiv (1869). 



3 Op. cit., p. 180, Taf. viii, figs. 99 and 106, Jm. 



* Op. cit., p. 12, fig. iv. 



* ' Trans. Roy. Soc. Edin.,' vol. xxxii. 



