THE 



PROCEEDINGS 



OF 



ROYAL SOCIETY. 



March 24, 1881. 



THE PRESIDENT in the Chair. 



The Presents received were laid on the table, and thanks ordered for 

 them. 



The following Papers were read : — 



I. The Croonian Lecture. — " Observations on the Locomotor 

 System of Echinodermata." By George J. Romanes, M.A., 

 F.R.S., and Professor James C. Ewart, M.D. Received 

 March 5, 1881. 



(Abstract.) 



I, — MOEPHOLOGT. 



In Hohthuria the polian vesicle opens freely into a wide circnlar 

 canal a short distance from the termination of the stone canal. From 

 this circular canal five lozenge-shaped sinuses project forwards, and 

 from each of these two large oval sinuses run forward parallel with each 

 other — the ten oval sinuses becoming continuous with the hollow 

 stems of the tentacles. Injection of the polian vesicle shows that it 

 forms one continuous tube system with the circular canal and its 

 sinuses, oval sinuses and tentacles, ampullae and pedicels. Unless the 

 pressure is kept up for a considerable time there is no penetration of 

 the injected fluid into the stone canal, and either the ring, the vesicle, 

 or a sinus gives way before the fluid reaches the madreporic plate. 

 Specimens injected with a gelatine mass show that each canal sinus 

 opens into a csecal tube, which runs forwards internal to the sinuses 

 of the tentacles as far as a wide circum-oral space. This space com- 



VOL. XXXII. B 



