NOTES ON EOHINODEEM MORPHOLOGY. 391 



opinion adverse to the views of Messrs. Vogt and Yung 

 respecting their vegetable nature, as these were not published 

 till 1885, and I did not become aware of them till March, 

 1886. 



On p. 154, after quoting from the " Challenger " report 

 some facts respecting the distribution of the sacculi, Perrier 

 adds : " Cette inegale distribution montre que ce ne sont pas la 

 des organes de quelque importance, si tant est que ce soient 

 des organes ; mais on ne pent rien conclure de ces donnees 

 relativement h leur veritable nature/' I am by no means sure, 

 however, that Perrier has drawn the right conclusion from the 

 facts of their distribution. 



I have no means of knowing what is his own view of their 

 nature ; but they are lettered z in his figures. The explana- 

 tion of these has not yet appeared, and I am therefore uncer- 

 tain whether z is explained as denoting " zooxanthelles," or 

 whether it is used for some other descriptive term. 



DESCRIPTION OF PLATE XXX, fig. 3. 



Illustrating Mr. P. Herbert Carpenter's Paper " On the Sup- 

 posed Presence of Symbiotic Algse in Antedon rosacea." 



Fig. 3. — Portion of a pinnule of Antedon acoela, with a very well- 

 developed ambulacral skeleton, x 20. 



p. The pinnule joints, c.p. The covering plates of the ambulacra, s.p. The 

 side plates, s. Notches in the distal edges of the side plates for the reception 

 of the sacculi (Zooxanthelles, Vogt and Yung). 



