Eig.9. The opening of the stone ©analinto the water 



rins is situated in "C" at the base of radial canal 

 5. but, by means of the rotation cf the hydrocoele 

 about the oesophagus together with the growth of 

 the ends of the horse-shoe, this opening is carried 

 away from its position at the base of radial canal 

 5. toward radial canal 1. It always remains however 

 nearer the former than the latter; in other words, 

 it comes to lie definitively in the ri-^ht edradius 

 Between radial canals 5. and 1. Compare Figs.G. and 9, 



The radial canals, which existed in "C" as sim- 

 ple pouches from the convex side of the hydroeoele, 

 have in"D" each become three lobed. Near the tip 

 and from -the sides of each canal a pair cf pouches 

 has budded out each of which is about equal in sizo 

 to the end of the canal which lies between and be- 

 yond them .Fig.O.et,. and tl. In these three struct- 

 ures we have the rudiments of the end tentacle and 

 first pair of foot tentacles of the ophiurid arm. 



When we were last considering the hypogastric 

 enterocoele it was in the form of a crescent , the 

 horns of which wex?e very short and its central part 

 ve?v wide. Into its concavity, which was anteriorly 



