Chemical Composition of the Calcareous Corals. 255 



silica exists in the coral in its soluble modification, and 

 probably is united to the lime. The free magnesia existed 

 as carbonate, and was thrown down as caustic magnesia by 

 the lime-water. Some small portion of lime was probably 

 thrown down as carbonate, in spite of every precaution to 

 the contrary. Only in two or three instances, however, was 

 there any effervescence on the addition of chlorohydric acid 

 to redissolve it. 



It need hardly be said that the existence in sea- water of 

 all the matters noted in these analyses is a just inference ; 

 but this subject, as well as the important geological in- 

 ferences which may be drawn from the results now pre- 

 sented, will be fully discussed on another occasion. 



My warmest acknowledgments are due to my friends 

 and pupils, Messrs D. Olmsted jun. and T. S. Hunt, who 

 have zealously aided me in the laborious parts of these 

 investigations. 



Yale College Laboratory, 

 December 16, 1845. 



— [From the American Journal of Science for March 1846, 

 an early proof of the above interesting Memoir having been obli- 

 gingly sent to us by the Editor^ Professor Silllman.) 



Distribution of Fossils in the different formations, and succes- 

 sion of Animals on the Surface of the Globe. By Professor 

 F. J. PiCTET. 



On a former occasion, we have taken some notice of those 

 associations of fossil species in each division of the crust of 

 the earth, which demonstrate the existence of a series of dis- 

 tinct faunas. The comparison of these faunas furnishes us 

 with important results, the generalisation of which enables 

 us to arrive at the laws which have regulated the succession 

 of organised beings. We shall afterwards shew that it is 

 probable some of these laws have been too hastily estab- 

 lished, and that an undue importance has often been given 

 to the facts on which they rest. But, notwithstanding such 

 errors, these generalisations have contributed in a remarkable 

 degree to advance the science of palaeontology, by shewing 



