371 



Tiiecidium Mediterraneum (pi. lxxiii. f. 80, 31, 32.) Risso. 



Testa; valva dorsali gibbosa, postice rostrata, antice subbilobata ; 

 valva ventrali planulata, operculiformi ; intus lamellis ad utrumque 

 latus lobulos duos, alteram semilunatum, magnum, alterum parvum 

 internum efformante. 



Shell with the dorsal valve gibbous, produced behind, and some- 

 what bilobate in front ; ventral valve flattened, operculiform ; 

 internal appendage lamellar, forming two lobes on each side, one of 

 which is large and semilunate, and the other very small ; they ad- 

 here throughout to the inside of the ventral valve. 



Found on Corals in the Mediterranean. 



ORBICULA, CRANIA, HIPPONYX, 



AND 



THECIDIUM. 



LIST OF FIGUKES IN PLATE LXXIII. 



Fig. 1. Orbicula lamellosa, 1. 

 2, 3. — kevis, 2. 

 4, 5. — tenuis, 3. 



6. — Cumingii, 4. 



7. — strigata, 5. 



8. — striata, 6. 



9. Crania personata, 1. 

 10, 11. — ringens, 2. 



12, 13, 14. — rostrata, 4. 



15,16,17. — Norvegica, 3. 



18, 19, 20. Hipponyx Mitrula, 2. 



21, 22, 23. — subrufa, 3. 



24, 25. — radiata, 4. 



26, 27. — barbata, 1. 



28, 29. — Ticaonica, 5. 



30, 31, 32. Thecidium Mediterraneum. 



