PLATE XIX. 



1. The face of the basal ring adjoining the " article basal.'' 



2. The central part of Fig. 3, showing the indistinct auchylosed sutures of the basal ring and the 



channels for the continuation of the axial cord cleared of axial cords and chambered organ. 



3. Interior view of basal ring, showing axial cords. 



4. Enlarged view of a part of the basal ring, to show the grooves for the muscular fibres and the fur- 



rows of the continuation of the axial cord to the calyx. 

 •V Chambered organ and axial cords. 



