PLATE XIII. 



jii, point of attachment of pinnule. 



1. Distal view of pinnule joint near base of pinnule near calyx. 



2. Oblique end view showing axial canal of pinnule joint near extremity of an arm. 



3. Profile view of young arm joint. 



1. Another joint, still nearer the end of the arm. 



5. Oblique view of a joint nearer the extremity of the arm than Fig. 3. 



(5. Same joint seen from inside to show the floor of the axial canal. 



7. Smaller joint, the third from the end of the arm. 



8. Penultimate joint of the arm. 



9. End view of a joint like that of Fig. 4. 



10. End view of a joint similar to Fig. 3. 



11. Proximal face of hypozygial, above the third fork. 



12. Syzygy face of hypozygial. 



13. Proximal face of another joint, from same part of arm. 



14. Distal face of same joint; pi, insertion of pinnule. 



15. Epizygial and hypozygial from the middle part of the arm above the third fork; pi, insertion of 



pinnule. 



