ASTERIAS PALLIDA. 



271 



The sum and pith of the sttitements of a large majority of 

 previous writers on tliis point then is to the effect that there is no 

 direct communication hetween the stone-canal and the axial sinus • 

 and Ludwig, the acknowledged authorit}' on echinoderms, sums up 

 the cpiestion thus ['78, p. 104] : " Nicht eines der Porenkanälchen 

 führt wo anders hin als in den Steinkanal (oder dessen nachher zu 

 besprechende ampullenförmige Erweiterung) ; das gesammte Canal- 

 system der Madreporenplatte stellt einzig und allein in Zusammenhang 

 mit dem Steincanal, aber nicht mit dem schlauchförmigen Canal, 

 noch aucli mit irgend einem anderen Hohlraum." Tlie direct con- 

 .nection of the stone-canal with the axial sinus is not even suspected. 

 Cuenot is even more explicit on this point ; he says ['''^7, p. 78], 

 " c^uoi qu'en disent MM. Perrier, Carl Vogt et Jung, il n'y a jamais de 

 perforations mettant en communication le canal du sable et les ])arties 

 environnantes, pas plus à h» base Cju'au sommet." 



It was with the hope of clearing up, if possible, this question that 

 I undertook an examination in serial sections of the |)art concerned, 

 and I may state iit once that tlie result has h,een a comj)lete confirma- 

 tion of the statements of Durham, Ihiry, and Maclh'ide. Figs. oO, 81 

 & 41-48 reproduce sections of the region concerned in the species I 

 have examined, viz., Asterias pallida, A. tenera, Solaster cndcca, Asterina 

 gibhosa, Grihrella santjuinolenta, Astropecten hispinosus, and Astrop. sp. The 

 dimensions of the specimens from which the sections Avere made are 

 stated in the explanation of figures, and it will be seen that Solaster 

 endeca and Asterias tdiiera are proljably represented by 3'oung indi\'i- 

 duals. In all these figures the direct communication of the aboral end 

 of the stone-canal and the axial sinus is very clearly seen and there is 

 no question that it represents a normal state of things. In most 

 species here represemed this communication is single, but in the species 

 of Astropecten from the Japanese coast represented by Fig. 48, there 



