PLATE XVI. 



1. Pinnule of base of arm. 



2. Pinnule of part of arm above first fork. 



3. Pinnule of the first third of second fork. 



4. Pinnule near end of main arm. 



5. Pinnule at base of last fork. 



6. One of the lower joints of a pinnule near the calyx, seen from above. 



7. End view of same. 



8. Oblique view of a similar joint, seen from the interior. 



9. Another joint near the middle of the same pinnule, seen from above. 



10. A joint of same pinnule nearer the end, with one wing but slightly developed, from above. 



11. Inside view of a joint with only one wing. 



12. A similar joint, seen from the inside. 



13. Joint without wings, near the extremity of the pinnule. 



14. Reticulation of wing of a pinnule joint. 



15. Reticulation of central part of joint, dorsal aspect. 



16. Reticulation of interior of joint, the anterior edge and part of the floor of the axial canal. 



17. Reticulation of edge of joint of pinnule. 



