IV CONTENTS. 



Chapter Pages 



XIII. Why arc Limestones comparatively rare in the Forma- 

 tions immediately succeeding the Archa3ans ? . . . . 83-88 



XIV. Some Crystalline Limestones have heen simply Minera- 

 lized 89, 90 



XV. Dolomites and Dolomitic Eocks have undergone Methy- 



losis 91-95 



XVI. Tho Chrono-Geological Eange of Ophites and related 



Rocks, and the Age of their Methylosis 96, 97 



APPENDIX. 



Thalassa and Xera in the Permian Period 99-106 



Supplementary Note A. Rock-jointing in relation to Pheno- 

 mena in Physical Geography and Physical Geology. . . . 107-117 



Supplementary Note B. On the Crystalline Bodies of the 



Sunderland Permian Magnesian Limestone 118, 119 



Supplementary Note C. Certain Limestones are of Mecha- 

 nical Origin 120, 121 



Description of the Plates 123-126 



Index . 127-142 



