PLATE XI I r. 



Fibularia ovulum, f. 1 -3. 



1. Seen from the aljactinal pole., |. 



2. Same, from the actinal side. 



3. Same, seen in profile. 



Peronella Peronii, /. J/., 5. 



4. Seen from the abaetinal side, nat. size. 



5. Seen from the actinal side, nat. size. 



Laganum Bonani, /. G, 7. 



6. Seen from the abactinal pole, nat. size. 



7. From the actinal side, nat. size. 



Peronella decagonalis, f. 8 - 11. 



8. Seen from the abactinal side, | nat. size. 



9. Seen from the actinal side, j nat. size. 



10. Abactinal floor removed to show the structure of the interior, | nat. size. 



11. Young specimen, nat. size, showing interior not materially different from larger speci- 



mens. 



