SYNOPSIS OF CONTENTS. ix Chapter XII.—The Llandovery Series : Lower Llandovery Rocks. PAGE History ..... 89 Unconformity between Lower and Upper Llandovery . . . 89 Llandovery fauna ... 89 Distribution of Lower Llandovery rocks, and value of the fauna . 91 Passage beds .... 92 Faunal relationship between Cara doc and Llandovery. . . 93 Geographical analysis of Llan dovery species . . . . 93 Palaeontology of Lower Llandovery rocks 95 Chapter XIII.—Upper Silurian Series. Geographical distribution Unconformity between the Upper and Lower Silurian . Subdivisions of the Upper Silurian series . . . . . Local distribution 98 Relation between Upper and Lower Llandovery species . 101 99 Characteristic fossils . . .101 Palaeontology of the Upper Llan- 100 dovery beds .... 102 IOO Chapter XIV.—The WENLOCK Group. Faunal value and geographical dis tribution of species . . .107 Tarannon shales, distribution and fauna 107 Denbighshire grits and their fauna 108 I Woolhope limestone and shale, physical conditions and palaeon tology of . . . . . 109 Characteristic Woolhope fossils 112 Chapter XV.—The Wenlock shale . . , .113 Characteristic Upper Wenlock fossils . . . . .113 Palaeontology of the Wenlock rocks . . . . Wenlock Limestone. Foreign equivalents . . .120 Identity of British and American Silurian life . . . .121 Chapter XVI.—The Ludlow Group. Range and fauna. . . .123 Lower Ludlow series — physical conditions . . . .124 Numerical estimate of fauna . 125 Characteristic Lower Ludlow species . . . . .125 The Aymestry limestone and its fauna . . . . . 125 Upper Ludlow series — physical conditions and range . .127 Fauna . . . . . .128 Ludlow bone-bed . . .129 Tile-stones—transition beds . 130 Ledbury shales . . . 13° Chapter XVII.— PALEONTOLOGY of the Ludlow Rocks. Numerical value of fauna Palaeontology in detail First appearance of fishes . I3 1 132 138 Tabular view of Cambrian and Silurian strata, with physical and palaeontological details 139-141 GENERAL Tables of the Organic Remains of the Lower PALEOZOIC strata 142-149 Summary of Lower Palaeozoic life . • • • • . • •150