METAMOKPHOSIS OF ASÏERINA GIBBOSA. 239 



circular eiiterocœl. It must strike one as rather remarkable 

 that such striking differences are to be found in two such nearly 

 allied forms. Further studies will probably throw light on this 

 point and lead to a better unification of the facts known. 



September, 1898. 



Postscript. 



In the discussion on the connection of the axial sinus and 

 the stone-canal contained in my paper on listerias I have quoted 

 the statement of my friend Dr. Cuenot to the effect that, there 

 is no connection between the axial sinus and the nei^îlibourino; 

 cavities (p. 271), This statement was extracted from his paper 

 of 1887; but I now find that in his paper of 1891 he distinctly 

 admits the existence of such a connection (p. 542), and I beg 

 here to express my regret for this unfortunate oversight on my 

 part. I must, at the same time, draw attention to the fact that 

 the connection admitted by Dr. Cuenot does not seem to me to 

 1)e the same as the one demonstrated b}'' me. He admits only 

 the indirect connection that takes place between the stone-canal 

 and the axial sinus by means of the anastomosing madreporic 

 canals that lead into the latter. The connection therefore lies, 

 according to Dr. Cuenot, inside the madreporite, while the one 

 demonstrated by me lies entirely outside the madreporite, as 

 may be inferred from the figures reproduced in my former paper. 

 The connection in question, therefore, takes place, according to 

 my observations, indirectly through the anastomosing madreporic 

 canals and directly through the passage of communication di- 

 rectly under the madreporite, the latter being the primitive 



