WHAT MAY BE LEARNED FROM EOZOON 147 



istic specimens, which are nevertheless very instructive. At 

 the Calumet some of the masses are partly filled with serpen- 

 tine and partly with white pyroxene, an anhydrous silicate of 

 lime and magnesia. The two minerals can readily be distin- 

 guished when viewed with polarized light ; and in some slices 

 I have seen part of a chamber or. group of canals filled with 



FIG. 18. Casts of Canals of Eozoon in Serpentine, decalcified and highly 

 magnified. 



_ 



FIG. 19. Canals of Eozoon. Highly Magnified. 



serpentine and part with pyroxene. In this case the pyroxene, 

 or the materials which now compose it, must have been intro- 

 duced by infiltration, as well as the serpentine. This is the 

 more remarkable as pyroxene is most usually found as an in- 

 gredient of igneous rocks ; but Dr. Hunt has shown that in the 

 Laurentian limestones, and also in veins traversing them, it 



