244 



Mr Silliman on the 



volume is just out of press, but can hardly be said to have 

 been published^ since the small number of copies (only two 

 hundred) will enable very few even of those most interested 

 ever to see the work. The investigations have led to some 

 unexpected results, which will be found to have an important 

 bearing on the subject of geology ; especially as serving to 

 explain in a more rational way than any heretofore offered, 

 the origin of those rarer ingredients in metamorphic lime- 

 stones and other rocks of animal derivation ; which have 

 always been a puzzle to geologists. 



No extended researches on the chemical constitution of 

 corals have been made, it is believed, since Mr Hatchett's, 

 already cited by Mr Dana. This chemist did not operate 

 quantitatively ' on any of the species examined by him ; and 

 his investigations tended to shew that the calcareous corals, 

 as well as the coverings of most of the molluscs experi- 

 mented upon, consisted merely of carbonate of lime. Such 

 was the opinion with which these chemical examinations were 

 commenced. But while they have found carbonate of lime to 

 be the principal ingredient, other elements have been de- 

 tected, shewing that coral is far from being the simple cal- 

 careous material supposed. 



The following is a list of the species examined, which are 

 here numbered for the convenience of reference : — 



1. Pontes favosa, Sandwich 



Islands. 



2. P. nigrescens, Feejees. 



3. P. limosa, Feejees. 



4. P. cyllndrica, Feejees. 



5. P. fragosa, Feejees. 



6. Porites,"^ Paumotu. 



7. Pontes,* Wakes Island. 



8. Porites,* Wakes Island. 



9. Madrepora palmata, West 



Indies. 



10. M. spicifera, Ceylon. 



11. M. prolifera, Bermuda. 



12. M. plantaginea, Ceylon. 



13. M. cytherea, Tahiti. 



14. Madrepora, Feejees. 



15. Madrepora, Feejees. 



16. Madrepora, Feejees. 



17. Madrepora, Feejees. 



18. M. cyclopea, Wakes Island. 



19. Pocillopora damicornis, 



Sooloo. 



20. P. elongata, Ceylon. 



21. P. grandis, Feejees. 



22. P. ligulata, Sandwich Islands. 



23. P. csespitosa. Sandwich Islands. 



24. Millepora tortuosa, Feejees. 



25. Heliopora coerulea. East Indies. 

 2Q. Gemmipora brassica, Feejees. 



27. Dendrophyllia nigrescens, 



Feejees. 



28. Meandrina phrygia, Ceylon. 



29. Astrsea orion, Ceylon. 



30. Astrsea, (p. 721, pi. 13, fig. 15.) t 



31. Astrsea, Wakes Island. 



32. Astrsea, Wakes Island. 



33. Astrsea, Feejees. 



34. Astrsea, Feejees. 



35. Astrsea, Feejees. 



36. Shell of Chama. 



♦ Worn specimens, not identified. 



t The references are to Mr Dana's work. 



