PLATE XXIII. 



1. Transverse view of upper pait of stem, see Plate XXII. Fig. 1, with ribbed and flat rings, to show 



the position of new rings intercalated between the old ones. 



2. The outer edge of two rings showing the new joint coming to the surface. 



3 Oblique view of a segment of two adjacent rings, with the intercalated new young joints. 



4. Sketch of two new joints, one of which has extended to the outer surface of the stem. 



5. An oblique view of a ribbed joint with a segment of a new joint in place inside of the serrations of 



the joint. 



6. The distal view of the new ring, forming on the top of the ribbed joint in Fig. 5. 



7. Segment of a new ring resting upon the face of Fig. 8. 



8. Portion of the edge of a ribbed ring showing the crenulations to the edge of the new ring. 



9. The distal face of the upper joint of Fig. i after the removal of the young joint, showing the seat 



for the new joint. 

 10. Reticulation of the central part of an old ring adjoining the axial cord. 



