In the upper oolites, it will be seen, is found the famous Portland stone, in which are some of the most remarkable specimens of the extinct fauna of this remote period. “They are found most plentifully in what is locally designated the ‘dirt-bed’ of Portland—a stratum of dark argillaceous mud, which must at one time have been the soil in which they and other vegetables flourished, but which, by a submergence of the land, was converted into the bottom of an estuary, over which other strata of clay, limestone, and sand were deposited. ‘At the distance of two feet,’ says Bakewell, ‘we find an entire change from marine strata to strata once supporting terrestrial plants; and should any doubt arise respecting the original place and position of these plants, there is, over the lower dirt-bed, a stratum of fresh-water limestone; and upon this a thicker dirt-bed, containing not only the cycadeæ, but stumps of trees from three to seven feet in height, in an erect position, with their roots extending beneath them. Stems of trees are found prostrate upon the same stratum; some of them are from twenty to twenty-five feet in length, and from one to two feet in diameter. The following section of a cliff in Dorset exhibits very clearly proofs of the alternation from marine strata to dry land covered with a forest, and of a subsequent submergence of the dry land under a river or lake which deposited fresh-water limestone.’” [Illustration: _a a a_, Portland stone (marine formation); _b_, Dirt-bed, consisting of black mould and pebbles (temporary dry land); _c_, Burrstone, and _d_, Calcareous slate (both of fresh-water formation).—_Chambers’ Geology, p._ 128. ] From the well-known quarries in Portland, a description of which would tempt us too far astray, have been procured the materials for St. Paul’s Cathedral, the Reform Club, and other public buildings. A visit to Portland, and examination of the quarries, such as we have twice paid, is well worth the attention of any summer tourist, and will richly repay, in its romantic scenery, and in the unique simplicity of its people’s manners, a week’s quiet stay at the King’s Arms, the once favoured and favourite inn of George the Third. Then, if we take the middle oolite, we shall find in it the well-known “coral rag,” so called because of the continuous beds of petrified coral found in great abundance, and in many places, apparently, in the same position in which they once grew at the bottom of the sea. We give below a few specimens recently obtained by us from the north of Wiltshire, from which it will be seen how closely they resemble those of existing species. [Illustration: OOLITE CORAL. (Nat. Size.) ] [Illustration: CORALS AND SPONGE FROM THE OOLITE. ]