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EXPLANATION OP PLATE LIX. 



Fig. 1. A transverse section tbrough a normal adult niedusa of Maerisia Jyonsi. 

 The section shows the four radial canals and gonadial diverticula, as well as 

 the four endodermal ridges in the manubrium. 



end., endodermal ridge. g-P-, gonadial diverticulum, lam., endodermal 

 lamella, man., manubrium, r.c, radial canal. 



Fig. 2. A similar section through a pentamerous specimen of the same species. 

 Note that although five radial canals and gonadial diverticula are well 

 developed, only four endodermal ridges occur in the manubrium, 

 Cf. p. 1048. 

 Lettering as in fig. 1. 



