THE PRESEEVATION OP EOZOON. 115 



present,, and its waters were probably warm and well 

 stocked with mineral matters derived from tbe newly 

 formed land^ or from liot springs in its own bottom. 

 On this point tbe interesting investigations of Dr. 

 Hunt witb reference to the cbemical conditions of the 

 Silurian seas^ allow us to suppose that the Laurentian 

 ocean may have been much more richly stored^ more 

 especially with salts of lime and magnesia^ than that 

 of subsequent times. Hence the conditions of warmth^ 

 light, and nutriment, required by such gigantic Proto- 

 zoans would all be present, and hence, also no doubt, 

 some of the peculiarities of itS mineralization. 



NOTES TO CHAPTEE Y. 

 (A.) De. Sterry Hunt on the Mineralogy op Eozoon and 



THE CONTAINING KoCKS. 



It was fortunate for the recognition of Eozoon that Dr. 

 Hunt had, before its discovery, made so thorough researches 

 into the chemistry of the Laurentian series, and was prepared 

 to show the chemical possibihties of the preservation of fossils 

 in these ancient deposits. The following able summary of his 

 views was appended to the original description of the fossil in 

 the Journal of the Geological Society. 



" The details of structure have been preserved by the intro- 

 duction of certain mineral silicates, which have not only filled 

 up the chambers, cells, and canals left vacant by the disap- 

 pearance of the animal matter, but have in very many cases 

 been injected into the tubuli, filling even their smallest rami- 

 fications. These silicates have thus taken the place of the 

 original sarcode, while the calcareous septa remain. It will 

 then be understood that when the replacement of the Eozoon 

 by silicates is spoken of, this is to be understood of the soft 



