20 



of interest. When Mr. Cuming visited the Island of Zebu, one of the 

 Philippine group, about twenty years since, he observed on some coral 

 reefs a number of dead shells of Calyptrcea equestris. Supposing that 

 living specimens could not be far off, he was induced, after much search, 

 to turn over a mass of coral that lay sunk about two feet in the sand just 

 below low-water mark. To his surprise he found the living C. equestris 

 attached by the foot to a separate calcareous plate. Upon further search 

 he discovered specimens of other species similarly attached, and some also 

 at the Island of Bohol ; and having secured the animal, he submitted it to 

 Professor Owen for dissection. The phenomenon was observed about the 

 same time at Mahe, one of the Seychelle Islands, by a distinguished French 

 conchologist, M. Dufo ; but no dissection appears to have been made by 

 him of the animal. Professor Owen found it to differ from other forms of 

 Calyptraidce " in the smaller development of its locomotive and respiratory 

 organs, and the greater development of the organs for the prehension and 

 assimilation of food." "The foot," continues the Professor, "may well 

 offer diminished proportions when the animal has chosen a site for the de- 

 position of its ventral plate and has taken up a fixed abode. Muscular 

 action being thenceforward much restricted, the necessity for extensive 

 respiration is in the same degree abolished." 



1. aculeata, Reeve. 



2. Adamsii, id. 



3. alveolata, A. Ad. 



4. Balanoides, Reeve. 



5. bulla, id. 



6. cancellata, Ad. fy R. 



7. cepacea, Brod. 



8. cicatricosa, Reeve. 



9. cornea, Brod. 



10. corragata, id. 



11. cyathella, Reeve. 



Species. 



12. diaphana, Reeve. 



13. donnitoria, id. 



14. equestris, Linn. 



15. fibulata, Reeve. 



16. Hipponicifonnis, id. 



17. Layardi, id. 



18. Martiniana, id. 



19. ossea, id. 



20. papyracea, A. Ad. 



21. porosa, Reeve. 



22. Roissyi, Dufo. 



23. sacchari-meta, Reeve. 



24. scabris, id. 



25. scutulum, id. 



26. stella, id. 



27. stultorum, id. 



28. tectum- Sinense, Ch. 



29. tortilis, Reeve. 



30. umbo, id. 



31. uncinata, id. 



32. Vanikorensis, Quo//. 



33. varia, Brod. 



Figure. 



CALYPTRiEA equestris. PI. 24. Fig. 139. Shell, in its place of attach- 

 ment on the rock, lifted to show the basal plate. — From Mr. Cuming's 

 Collection. 



