THE PRESERVATION OP EOZOON. 123 



ing with picrosmine, and surrounding masses of Eozoon in 



the Laurentian limestones of that region ;* the Eozoon itself 



_being there injected with a hydrous silicate which may be 



jscribed as intermediate between glauconite and chlorite in 



iposition. The mineral first mentioned is compared by 



toffman to fahlunite, to which jollyte is also related in physical 



laracters as well as in composition. Under the names of 



ihlunite, gigantolite, pinite, etc., are included a great class of 



rdrous silicates, which from their imperfectly crystalline 



mdition, have generally been regarded, like serpentine, as 



jsults of the alteration of other silicates. It is, however, 



icult to admit that the silicate found in the condition 



jscribed by Hofi'man, and still more the present mineral, 



^hich injects the pores of palaeozoic Crinoids, can be any other 



lan an original deposition, allied in the mode of its formation, 



the serpentine, pyroxene, and other minerals which have 



ijected the Laurentian Eozoon, and the serpentine and 



glauconite, which in a similar manner fill Tertiary and recent 



shells." 



(C.) Yaeious Minerals tilling Cavities or Fossils in the 

 Laueentian. 



The following on this subject is from a memoir by Dr. Hunt 

 in the Twenty-first Report of the Regents of the University of 

 Neiv York, 1874 :— 



" Eecent investigations have shown that in some cases the 

 dissemination of certain of these minerals through the crys- 

 talline limestones is connected with organic forms. The ob- 

 servations of Dr. Dawson and myself on the Eozoon Canadense 

 showed that certain silicates, namely serpentine, pyroxene, and 

 loganite, had been deposited in the cells and chambers left 

 vacant by the disappearance of the animal matter from the 

 calcareous skeleton of the foraminiferous organism ; so that 

 when this calcareous portion is removed by an acid there 

 remains a coherent mass, which is a cast of the soft parts of 



* Joiirn. fiir Prakt. Chemiei Bd, 106 (Erster Jahrgang, 1869), p. 

 356. 



