WHAT MAY BE LEARNED FROM EOZOON 



145 



manner, in certain Silurian limestones from New Brunswick 

 and Wales, in which the delicate microscopic pores of the 

 skeletons of stalked starfishes or crinoids have been filled with 

 mineral deposits^ so that when decalcified these are most beau- 

 tifully represented by their casts, Dr. Hunt has proved the filling 

 mineral to be^ intermediate between serpentine and glauconite. 

 We have, therefore, ample warrant for adhering to his con- 



FiG. 16. — Joint of a Crinoid, having its Pores injected with a Hydrous 

 Silicate. Upper Silurian Limestone, Pole Hill, New Brunswick. Magni- 

 fied 25 diameters. 



elusion that the Laurentian serpentine was deposited under 

 conditions similar to those of the modern greensand. Indeed, 

 independently of Eozoon, it is impossible that any geologist 

 who has studied the manner in which this mineral is associated 

 with the Laurentian limestones could believe it to have been 

 ^ Silicate of alumina, iron, magnesia, and potash. 



