ADVERTISEMENT. 1. 2. 3. 4. 5. 6. 7. Hypozoic I'ocks. f(i) Older Cambrian groups inferior to the Bala limestone. Cambrian locks. Upper Cambrian groups based on the Bala limestone. Caradoc group. It has perhaps no distinct representative in Scotland and the North of England. In Wales and Shropshire, it often overlies the Cambrian rocks unconformably, and there forms the physical basis of all the Upper Silurian groups, while Paleontologically it connects itself with the Cambrian rocks. Upper Silurian rocks—including all the groups from the upper part of the Wenlock Shale to the Tilestone. Old Red Sandstone, or Devonian, groups. Carboniferous groups. Permian groups, which end the Paleozoic series, and are immediately followed by the Trias, or New Red Sandstone. In concluding this notice, I have to return my grateful thanks to the Syndics of the University Press for generously taking on themselves the expense of the letter-press of this Part; which, after all the assistance thus given to me, has not been brought before the public without much anxiety, and a great personal cost. Cambridge, May, 1851. ADAM SEDGWICK, Woodimrdian Professor.