Granite of Firbogh. Galway Bay.—I propose, as time and opportunity permit, to give the results of observations on the microscopic structure of Irish Granites, commencing with one from Galway.

Many Geologists will hail with satisfaction the accession of Prof. Hull to the ranks of the few who appreciate the importance of a microscopic examination of rocks; and the communication from him which appeared in the last Number of the GeologicalMagazine is the more welcome, as it contains a promise of further researches in the same direction.

Every one who has traversed our Chalk Downs must have noticed here and there shapeless masses of grey stones, half buried in the turf. Sometimes they are found in groups, like the shattered ruins of some ancient temple, and at other times they occur in isolated blocks, as though giant hands had hurled them at random over the hills in wanton sport. At one place, near the village of Kennet, they assume the appearance of a multitudinous flock of sheep, and are known by the appropriate designation of “Grey Wethers,” whilst at other places in the same vicinity they bristle on the hill-sides, and trail along the valleys like the débris of an avalanche or the moraine of a glacier. Nowhere do they exist in such profusion as on the west of Marlborough, but they are found scattered over the whole Chalk area of this district. At the western end of it they consist chiefly of saccharoid sandstone. Further east, especially around Newbury, they become smaller, harder, and more crystalline; whilst in the neighbourhood of Great Bedwyn, and occasionally elsewhere, they take the form of pudding-stone, being agglomerations of flint pebbles, cemented together in a matrix of siliceous sand.

It was contended in a previous communication that all valleys have been formed by sub-aërial agencies alone, and that the disintegrated materials, being carried seaward by the rivers traversing them, have accumulated to immense thicknesses in what had been formerly a continuation of these valleys, and have, by their weight, caused progressive subsidence, and so have formed bays and to some extent deltas at and near their mouths.

These Foraminifera were obtained from fifteen zones of the Jurassic strata, between Solothurn, in Switzerland, and the Eichberg, in Baden: three Liassic zones (Black or Lower Jura); six in the Brown or Middle Jura; and six in the White or Upper Jura; beginning with the Turneri-zone of the Lower Lias, and ending with the Pteraspis-zone of Schaffhausen. The Numismalis marl, Amalthei-clay, Murchisonæ-bed, Discoidei-marl, Crenularis-bed, the Coral-limestone, and the Virgulian stage yielded few or no traces of Foraminifera.