PLATE LII. 
A. An elliptical oolitic body composed entirely of siderite (iron-carbonate). ‘The original 
material is believed to have been calcite, but this has been replaced by the siderite. 
During the process of replacement, the original form and structure of the nodule 
have been destroyed. (Specimen 11, camera-lucida drawing, x 50, Blackwelder, 
page 382.) 
BR. A partially recrystallized oolitic body. The crescent-shaped area on the upper side 
of the figure is composed of granular calcite, in which traces of banding are still visible. 
(Compare Plate LV, D.) The rest of the corpuscle is composed of a few large clear 
crystals of calcite which are devoid of the concentric structure. These are believed 
to represent a later growth than the granular portion. (Specimen 11, camera-lucida 
drawing, X 50, Blackwelder, page 382.) 
C. A granular crystalline oolitic body. ‘The entire rock is composed of small interlock- 
ing grains of calcite. Traces of the original concentric banding in the oolitic body 
are indicated by the faint dusky circles which pass through the crystals indiscrimi- 
nately. The calcareous mud has crystallized, and the crystals in their growth have 
absorbed the streaks of impurities without disturbing their position. (See also Plate 
LV, D.) (Specimen 18, camera-lucida drawing, x 90, Blackwelder, page 381.) 
D. Periphery of a flint nodule in dolomite. The dark portion on the left is minutely 
granular dolomite, darkened with carbonaceous matter; this forms the mass of the 
rock. ‘The rest of the circle is occupied by a portion of a spherical nodule of black 
flint. The lighter part is well-crystallized calcite which has been deposited in geode- 
like arrangement. The dotted area represents finely crystalline silica, darkened by 
carbonaceous impurities. (Specimen 151, caimera-lucida drawing, x 40, Blackwelder, 
page 469.) 
E. Field drawing of conglomeratic limestone showing the apparent radiate arrangement 
of the nodules in the plane of bedding. Sketched from a polished monumental slab 
on Hu-lu-shan Butte near Yen-chuang, Shan-tung. (Willis, about 4 natural size.) 
