NOTES ON EOHINODERM MORPHOLOGY. 387 



other seven species of Antedon obtained at this station. 

 They are also present on an example of this same species found 

 at Station 169; but there is no sign of them in Eudiocrinus 

 semperi, from the same station, nor in another individual of 

 this latter type from Station 164, where they are present 

 between the side plates of the ambulacra in Antedon 

 acutiradia, five specimens of which were obtained by the 

 " Challenger." 



The above facts seem to me to tell very decidedly against 

 the supposed algal nature of the sacculi, which are so eminently 

 characteristic of certain endocyclic Crinoids, and never occur 

 in the exocylic Actinometra. They occur wherever An- 

 tedon is found, from nearly 82° N. to below 52° S., and at all 

 depths down to 2600 fathoms; but they are not to be found 

 in species of Actinometra which live side by side with 

 Antedon in the warmer parts of the world, and I pointed out 

 in 1882^ that this fact is one of considerable importance in 

 the generic distinction of the two forms. I cannot think that 

 Messrs. Vogt and Yung are aware of it, however, or they 

 would hardly have committed themselves to the following 

 statement : 2 — " Les Comatulides libres (Antedon, Actino- 

 metra) offrent fort peu des differences anatomiques, et sauf 

 quelques details insignifiants, sont construites absoluraent sur 

 le meme plan que notre espece type.^' The absence in Acti- 

 nometra of the sacculi, which are almost always present in 

 Antedon, may be a "detail insignifiant ;'^ but it is, at any 

 rate, one which may possibly turn out to be fatal to Messrs. 

 Vogt and Yung^s theory of the vegetable nature of these 

 structures. 



1 cannot imagine any reason why the " amoeboid spores,'^ 

 which have given rise to such abundant "veritables zoospores ^^ 

 along the pinnule ambulacra of Antedon carinata and 

 A. microdiscus at Bahia and at Cape York respectively, 

 should not have had equal opportunities for developing in the 



' " Preliminary Report on the 'Blake' Comatulse," 'Bull. Mas, Comp. 

 Zool.,' 1882, vol. ix, No. 4, p. 11. 



2 Op. cit., p. 571. 



