bed of controversy. In the present state of our knowledge, however, we are not warranted in doing otherwise than M. Barrande has done. He holds that all three divisions in Bohemia are essentially sections of one great system, viz. the Silurian, even though the two uppermost possess fossils common to both, whilst none are common to them and the lowermost. His views (and every opinion now expressed by M. Barrande, stamped as it must be by experience and ability, is deserving of the highest respect and consideration) are essentially identical with those of Sir Roderick Murchison, and all tend to maintain the unity of the great Lower Palæozoic system.

Among the Thuringian mountains there is another Silurian region, one which of late has yielded many interesting and characteristic fossils that enable the geologist distinctly to recognise true Lower Silurian strata. Peculiar complications and local disturbances, arising from the interference of eruptive rocks, render the interpretation of this district a work of no ordinary difficulty. Fifteen years ago Professor Sedgwick and Sir Roderick Murchison jointly commenced the work, and indicated the true general succession of the constituent formations. In the mean time German geologists have worked the ground in detail, discovered important evidences derived from organic remains, and constructed geological maps founded on good trigonometrical surveys. Last year Sir Roderick hied back to the ground, accompanied by Professor Morris, and brought all his rich experience to bear upon its exploration. He can now speak definitely of the age of the Silurians of the Thuringer-wald, and assign them without question to the Lower division. No Upper Silurians have been recognised there, the sedimentary rocks next in succession being Devonian. A significant suggestion is thrown out by the author in the volume before us, well deserving of attention and inquiry at the school of Freiberg.

6

We have yet to learn,' writes Sir Roderick, how much of the primary clayslate or "thonscheifer" (mapped by Naumann and his associates) is to be abstracted from unfossiliferous rocks, and grouped with the lower members of the series (Silurian) we have been considering. Other inquirers may seek to ascertain to what extent many of these ancient schists and slates, evidently of sedimentary origin, have been converted into mica schists, and even into the metalliferous socalled "gneiss," amid which the illustrious Werner himself taught his lessons in Freiberg. It would seem presumptuous that a passing geologist should hazard any opinion on such a point. Still I venture to state that much of the so-called gneiss in the plateaux around Freiberg is a rock very different in age from the antique and crystalline gneiss of Scotland and Scandinavia. I would, indeed, suggest that those portions of it which are separated by wayboards, and exhibit several of

the

the features of bedding and jointing of aqueous deposits, may prove to be of no higher antiquity than the lower members of the sedimentary formations under review.'

If we are not greatly mistaken, the hint conveyed in this passage will, before very long, prove pregnant of geological discovery, not only in the district immediately referred to, but in other German localities.

In France Silurian rocks appear in Brittany, where, like the people who live upon them, they seem to hold a close analogy and relationship with the foundation stones of our own Cornwall. They consist of bluish fossiliferous schists-those of Angers are well known-furnishing roofing-slates, resting upon conglomerates and siliceous sandstones, which rest in their turn on unfossiliferous glossy schists of great antiquity, and possibly comparable with our own Longmynd rocks. The number and distinctness of the organic remains in the French Silurians afford many facilities for assigning these rocks their places as equivalents of British types. The result is that we must regard them as entirely belonging to the Lower division, and as constituting representatives of our Llandeilo and Caradoc divisions.

M. de Verneuil has established beyond question the Silurian age and relations of ancient stratified rocks in Spain. In that country they present features very similar to those exhibited by the corresponding formations in Brittany, and must be regarded in the main, if not entirely, as of Lower Silurian age. In the Sierra Morena and other localities well-marked fossils occur, many of them French and some Bohemian species. The famous quicksilver-mines of Almaden, and some of the richest lead and silver mines near Carthagena and in the Sierra Almagrera, are worked in Lower Silurian rocks; and it would seem probable that those of the Sierra di Gador and Sierra Nevada are located in highly metamorphosed strata of the same age.

Most of what is accurately known of the rocks of Portugal is due to an able English geologist, Mr. Daniel Sharpe, who during moments of leisure and occasional visits to that country has worked wonders in the way of making out its structure. Among other results he has demonstrated the presence and investigated the order of succession of older Palæozoic strata in the neighbourhood of Oporto. A rising native observer, M. Carlos Ribeiro, following in the steps of Mr. Sharpe, and assisted by that gentleman in the determination of the fossils he has collected, has traced an axis of Silurian rocks from north-north-west to southsouth-east far beyond the Douro. They form, in fact, the crest of the famous Serra de Busaco, a locality that will hereafter share its military fame with the interest it now derives from scientific considerations.

The

The greater part of the Mediterranean region is bounded by rocks of much more recent origin than the Silurians. In the island of Sardinia, however, the eminent topographer, General della Marmora, has proved the presence of Silurian rocks, and it is probable that both Upper and Lower Silurians are there to be found. But around this famous sea and among its archipelagos there are not many certain traces of Palæozoic strata. Devonian rocks, with their characteristic fossils, are met with in Turkey and in Asia Minor, and the coal of Eregli, with which the Turks have been feeding their steam-engines whilst we were calling for supplies from home for our fleet, is of true carboniferous age, and as nearly as possible the equivalent of our Newcastle or Lancashire coal-measures. Captain Spratt, R.N., of the Spitfire, an excellent geologist, has recently visited and examined these coalmines, and has set the question of their age at rest by an examination of their fossils, specimens of which, sent by him to England, fully confirm the conclusions which he came to on the spot.

Although vast expansions of Palæozoic strata, especially rocks of Devonian age, are known to constitute a considerable portion of Asia, veritable Silurians have not been detected there except in a few localities. What is known of their appearance is sufficient, however, to warrant the inference that they are present, although hidden beneath the Devonians that rest upon them, and it is extremely probable that before many years are over considerable superficial Silurian tracts will be discovered in Asiatic regions. China may especially be looked to as a grand field for future geological research. Thanks to the eccentricities of the Celestials, we are acquainted with their fossils through the contents of their druggists' shops. The most old-fashioned of mortals are true to their antiquated notions even in their medicines, and grind up Palæozoic organic remains in order to set their stomachs right. Our Welsh friends, with all their love of antiquity, never thought of powdering Snowdon for an alterative, or converting Bala limestone into an effervescing draught. Had the Chinese been better geologists, they would have imported their fossil physic from the Himalaya, where Capt. R. Strachey has made known the existence of true Silurian strata.

In New South Wales Silurian rocks have been discovered by the Rev. W. B. Clark, and, almost as we are writing, we hear of the well-conducted labours of a highly promising young geologist, Mr. Alfred Selwyn, who directs the geological survey of Victoria, having been rewarded by the discovery of fossiliferous strata of like age. He had previously shown the existence and structure of a mass of ancient metamorphosed slates and sand

stones,

stones, not less than 35,000 feet in thickness, and suggested their parallelism with the Cambrian or Lower Silurian strata of Great Britain. Independent of the numerous questions of interest connected with the distribution of gold in Australia, that vast country promises to be a grand field of fresh information for the geologist. Every day shows more and more variety of structure, and develops new evidence, both paleontological and mineralogical, Geological knowledge is there a valuable qualification to the emigrant and settler; one that may enable him to choose ground with comparative certainty, and regulate his explorations with better prospects of success; whilst, in a country where mines of all kinds and of wonderful richness are turning up from time to time, an acquaintance with what is known respecting the phenomena and distribution as well of metalliferous veins as of coal and iron beds can scarcely fail to confer on its possessor a superiority over ignorance and empiricism, and open out to him the pathway to profit.

Sir Roderick Murchison may reasonably indulge some sentiments of pride when he wheels round his globe and looks upon the new world as coloured by the geologist. Almost from end to end of the far-extending American continent, he will see the influence of his researches manifested in the determination and nomenclature of Transatlantic rocks. From Chili northwards to the Rocky Mountains and the Sierra Nevada, the backbone of the western continent would appear to be in part constructed of Silurian strata, or rather to be bounded, like the human spine, by long strips of Silurian muscles. Much of the richness of the new world, its store of gold and silver, appears to be connected with these ancient bands. In several localities among the Andes well-marked fossils have been found, unquestionably Silurian, as we know from the collections first made by Mr. Pentland, and from the work of M. Alcide d'Orbigny. North America might almost be said to be the head-quarters of Silurianism. A glance at the excellent map appended to Sir Charles Lyell's Travels will show how vast are the regions there occupied even superficially by Silurian deposits. Exceedingly prolific in organic remains and varied in mineral character, these beds have furnished the subjects of some of the most excellent geological treatises that have appeared during the last ten years. They are too numerous to be cited. It certainly is one of the most striking features of the science of the United States, that geology has taken root there deeply, and has flourished perhaps beyond any of the sister-sciences. The American geologists have gained a worldwide fame, and deservedly. Their works are text-books in Europe and standard members of our scientific libraries.

A

considerable

considerable number of these excellent monographs have been published at the cost of different States of the Union, whose local governments have thus shown an advanced and enlightened spirit, and a just appreciation of the advantages that must accrue to their citizens through the timely development of the resources of the land. The bold and adventurous kind of work necessarily characteristic of any geological survey conducted in great part over thinly inhabited and partially explored regions, seems to have suited the somewhat nomadic spirit of an American philosopher, better than the learning of the closet or the science of the schools. We have much yet to hope from the onwardstriding pace of American geology.

In the mean time our own Transatlantic governments have not been neglectful of the good work of science. In Canada especially there has been proceeding for some years one of the most extensive and important geological surveys now going on in the world. The enthusiasm and disinterestedness of a thoroughly qualified and judicious observer, Mr. Logan, whose name will ever stand high in the roll of the votaries of his favourite science, have conferred upon this great work a wide-spread fame. The Silurian rocks play a prominent part in the structure of the Canadas, and the analogy of many of the subdivisions with European strata is exceedingly striking. Around the inhospitable shores of the Icy Sea, our famous arctic explorer Sir John Richardson has collected Silurian fossils, and proved the presence of Silurian strata; and amid the intricacies of the polar fiords and archipelagos our daring navigators have collected rock specimens filled with well-marked Silurian shells, not a few of them identical with the fossils of Dudley and Gothland.

The series of American Silurians is most complete, and includes representatives of all the European stages, with possibly additional and intervening formations. The attempt to parallel stage with stage on either side of the Atlantic has perhaps sometimes been carried too far; nevertheless there is unquestionably a striking series of analogies presented by these ancient deposits in Europe and America, and any candid man of science who will sit down unprejudiced and sift the evidence must rise from his inquiry with strong feelings of admiration at the extent of the labour and the carefulness of research that have led to these results.

The preceding summary enumeration may serve to illustrate the geographical distribution of Silurian formations as at present known. Now, when it is recollected that the Silurian System,' that great work in which its author fully stated and co-ordinated

the