a. Sedgley ridge, or anticlinal, containing the Aymestry limestone.
b. Hurst ridge.
c. Wren's Nest, Wenlock limestone.
d. Dudley Castle ridge, Wenlock limestone.
e. The Hayes, upper Ludlow formation.
f. Rowley hills of basalt.
g. Barrow hill of basalt.
h. Coal deposit, resting somewhat unconformedly on the Wenlock formation, and partly resting on, partly passing under, the Rowley basalt which chars it.
Tyrone. The Llandeilo limestone forms a line from Broughton by Coniston Waterhead to Hougill fells, and between this and Kirkby Lonsdale are fossiliferous schists. The Lammermuir Hills present on their northern side a considerable exhibition of Silurian strata (Sedgwick, in Brit. Assoc. Rep. for 1850). In Brittany Silurian fossils occur: the limestones of Christiania and Gothland belong to this system. Perhaps the most remarkable and complete series of Silurian deposits on the continent of Europe is that of Bohemia, worked out by M. Barrande, from whose patient hands a valuable memoir is expected. It is said by Mr. Strickland to occur about Smyrna with asaphi. It is found near Oporto with coal (Sharpe). Perhaps it is from these rocks that trilobites are obtained near the Cape of Good Hope, by Sir J. Herschel. In North America the Silurian system is largely developed: its classification contains many more terms than have been found necessary in Europe. The
