74 
the smaller interspaces between the Foraminiferous atoms 
both enclosed within, and external to the Nautilus, render- 
ing the limestone capable of receiving a high polish. 
If these explanations are as correct as I believe them to 
be, we have here the entire history of the origin of a lime- 
stone rock — from the first accumulation of the Foraminiferous 
ooze, as seen in the interior of the first large chamber of the 
Nautilus, to the deposition, in an inorganic mineral form, of 
the crystallized carbonate of lime within the closed chambers 
of the Nautilus ; all being illustrated within the area of a 
slab of limestone little more than a foot in diameter. 
