Plate 22. 



Molar-tooth structure in Siyeh limestone (weathered), Clarke Range. Sunken parts 

 calcium carbonate ; remainder dolomitic. Two-thirds natural size. 



Molar- tooth structure in Castle Mountain dolomite (unweathered) on main line of Canadian Pacific 

 Railway. Light parts dolomitic ; dark parts calcium carbonate. Two-thirds natural size. 

 25a — vol. ii — p. 174. 



