NOTES ON SYNAPTA. 369 



left of the dorsal one. A few also occur scattered over 

 the walls of the coelom. Their function is at present 

 unknown. 



Explanation of Plates XVI. and XVII. 



List of reference letters. 



c/ Ciliated funnels; cy?i, circular muscles; conr circum 

 oral nerve ring ; ctl connective tissue layer of body wall ; 

 cwv circum-oral water vessel ; cr calcareous ring ; dv 

 dorsal vessel ; e ectoderm ; g gonad ; ga genital aperture ; 

 ^ intestine ; Imh longitudinal muscle bands ; m mesentery; 

 mlt muscular layer of tentacles ; mt miliary granules ; 

 ;pv Polian vesicle ; rn radial nerve ; t tentacles ; tp ten- 

 tacular pedicels ; tnl tentacular nerve ; ts tubular space 

 underlying nerve ; vv ventral vessel ; lo water-tube. 



Plate XVI. 



Fig. 1. Diagram of the anatomy of Synapta inluerens, 

 constructed from dissections and serial sections. 



Fig. 2. Diagram of a transverse section of Synapta 

 inhcerens. 



Plate XVII. 



Fig. 1. A tentacle of Synapta inhcerens showing the so- 

 called tentacular pedicels in situ. 



Fig. 2. Outline figure of a tentacle of Synap)ta digitata, 

 showing the bodies described by Hamann as 

 sense organs. 



Fig. 3. {a) A tentacular pedicel viewed in situ; (b) 

 vertical section of the same. 



Fig. 4. Diagram of a longitudinal sectioji of a tentacle of 

 Synapta inhcerens. 



