It is proposed in the following pages to give a concise account of the progress of investigation of the lower Palæozoic rocks during the last forty years. The subject may naturally be divided into three parts: 1. The history of Silurian and Upper Cambrian in Great Britain from 1831 to 1854; 2. That of the still more ancient Palæozoic rocks in Scandinavia, Bohemia, and Great Britain up to the present time, including the recognition by Barrande of the so-called primordial Palæozoic; fauna; 3. The history of the lower Palæozoic rocks of North America.

The ore which is the subject of this paper occurs in rather an uncommon manner; its existence, however, has been known for a very considerable period, and it is said to have been worked at least 250 years ago. I believe it is this that is referred to in Dr. Boate's quaint work,“Ireland's Naturell History,” as being found “by the side of the rivulet Lishan, not far from Lough Neagh,”—although he classes it with the ordinary clay-ironstones, which it certainly does not resemble either in composition or appearance.

The Geology of Dorset presents an almost consecutive series of formations from the Liassic to the Quaternary. The Rhætic beds which have so large a development in the neighbouring counties of Somerset and Gloucester, just touch the confines of the county near Lyme Regis, and were described by Mr. H.W. Bristow, F.R.S., Director of the Government Geological Survey, at the Bath Meeting of the British Association in 1864, as everywhere underlying the true Liassic strata.

It must be admitted that if during the Glacial period an arctic current, similar to that which now sweeps along the east coast of North America, were to pass over the submerged portions of our island, there is no reason why the climate of this country should not assimilate to that of Labrador, where there is now perpetual frozen ground in the latitude of Liverpool. The question then is, what evidence have we that such a current existed at the commencement of the Glacial epoch ? Have we not the evidence of the striæ on the rocks and mountains of the Scandinavian peninsula, as well as on those of our own country, to show that, during the period of the submergence of these districts, icebergs were driven by an arctic current from the north-east to the south-west ?—that the Polar Sea extended from the White Sea to the entrance of the Baltic, spreading southward over Germany to the confines of Switzerland, which can be traced by the deposited boulders and other ice-transported materials ? Then, as to the cause of this return current. It must be evident that the Gulf-stream at that date could not have flowed in its present direction. The arctic current coming down the Baltic must have thrown it further to the west, so that in all probability in its northern progress it would impinge on the east coast of Greenland and the Island of Spitzbergen; then being deflected by the polar ice, it would return by the way of the White Sea and the Baltic, so completing the circuit.