THE NATURALIST, 1913 PZATE XX: 
No. 5.—Included matter in fossil bone. 
: Polished surface (flat) on left. On the right (showing relief) is the 
surface after etching withtHydrochloric acid. The dark portions represent hollows 
produced by the action of the acid. Magnified 30 diameters. 
No. 6.—The same specimen as in No. 5, more highly magnified, showing 
silicification of the outer envelopes of two of the Oolitic grains. The dark parts in the 
photo were filled with Carbonate of lime. Magnified 50 diameters. 
