176 



Proceedings of the Koyal Physical Society. 



Figs, I to 4. Horizontal sections (drawn with camera lucida, x 20) of madreporite, and 

 underlying parts in a large adult S. endeca. The sections are looked at from 

 the aboral side, and the centre of the starfish disc is towards the lower side of 

 the page. 



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Fig. 1. See above. Section near the beginning of the series. As the external surface of 

 the madreporite is convex, pore canal openings appear at the margin, while 

 towards the centre we have chiefly larger or smaller collecting trunks. 





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Fig. 2. See above. Section a little deeper, showing commencement oi central chamber as 

 well as the openings of two large collecting trunks which enter it near the 

 middle of its convex side, 



