174 Proceedings of the Royal Physical Society. 



XIX. — Notes on the Adult Anatomy of Solaster endeca (Forbes) : 

 (i) Madreporite, etc.; (2) Anus; (3) Egg ducts; (4) and (5) 

 Aboral and Oral Perihaemal sinuses. By James F. Gemmill, 

 M.A., M.D., D.Sc. 



(Read 28th November 193 0. Received 10th March 1911.) 



1. Kelation of Pore Canals of Madreporite to Stone Canal 

 and Axial Sinus (Figs. 1-5). 



As is well known, in the larval condition and at metamorphosis, the pore 

 canal is single and leads into the axial sinus. During this period the stone 

 canal, which was formed in the sinistral 1 wall of the axial sinus, com- 

 municates with the axial sinus by a single aperture situated near the 

 internal end of the pore canal, and looking dextrally 1 into the cavity of 

 the sinus in question. 



Two points arise in connection with the later growth of starfish — (1) "What 

 are the final relations of the usually numerous pore canals of the madreporite 

 to the stone canal and to the axial sinus ; and (2) How have these relations 

 arisen, and, in particular, how do the pore canals come to be so numerous. 

 The first of these points only will be taken up in this paper. 



Many of the older observers had noted that injected fluids passed readily 

 from the stone canal into the axial sinus, within or underneath the madre- 

 porite. This method is, however, open to the objection that by its employment 

 delicate septa may be ruptured, and more recently the question has been 

 studied by means of sections (Ludwig, Perrier, Hamann, Cuenot, Durham 

 and Goto). 



Ludwig's account (1) now stands practically alone in affirming that all 

 the pores of the madreporite open into the stone canal, and that the latter is 

 entirely separated from the axial sinus. 



Cuenot (3) states that many of the madreporic pores lead into the 

 axial sinus, and that this sinus and the stone canal are placed in com- 

 munication by means of anastomosing channels in the madreporite. Hamann 

 (2), though his earlier work was in agreement with Ludwig, gives a later 

 description similar to that of Cuenot. 



Durham (4) states that in a full-grown specimen of Cribrella oculata (a) one 



1 Throughout this paper dextral and sinistral indicate respectively the sides towards 

 which, or away from which, the hands of a watch would seem to move on the starfish disc 

 as viewed ahorally. 



