PLATE XI. 



1. Calcareous network of limestone of a side plate of food groove near middle of arm. 



2. Large covering plate with terminal reticulation grown into spines. 



3. Covering plate of food groove of pinnule, with large open meshwork extremity. 



!. A smaller covering plate of the same groove as Fig. 2, also terminating in spines. 



5. Thickening of reticulation to form a lateral spine. 



6. One of the spines of the side plates. 



7. Another of the spines of the side plates. 



8. 9. Small covering plates of end of arm joint near extremity of arm. 



10. Calcareous limestone network of side plate of food groove of pinnule., about middle of arm. 

 1 1 Covering plate of same pinnule nearer base of same, seen from above. 



12. A similar covering plate to that of Fig. 11. seen from the interior face. 



13. Profile view of covering plate, showing the wings connecting them with the side plates (Fig. 10). 



See spines of Fig. 9, Plate X. 



