In almost every collection of minerals there may be found specimens of the curious little glassy balls, which, from the locality of their occurrence—the great Marekanka, near Okhotsk in Siberia—have received the name of Marekanile. These glassy balls are more or less perfectly rounded in form, they vary in their colour, through different shades of smoke-grey to orange-brown, while in size they range from the dimensions of a pea to those of a walnut. Most mineralogical treatises still continue to recognize Marekanite as a mineral, and class it either as a variety of Obsidian or of Pearlstone.

While totally disallowing the claim of Marekanite to rank as a mineral-species or even variety—the petrographer recognizes in this substance a type of rock, which proves to be by no means devoid of interest, when its properties are carefully studied, nor destitute of suggestiveness, when its mode of occurrence is thoughtfully considered.

A Year or two ago we received from Mr. James Bennie, of the Scottish Geological Survey, a washing of Lower-Carboniferous shale from Plashetts, Northumberland, which was very rich in the remains of Ostracods. Among other species occurring therein was a Beyrichia-like form, ribbed as in Kirkbya, and with a wide fringe about the free margins of each valve.

Under the influence, perhaps, of the prevailing idea of evolution in all things, the conviction has been growing in the minds of geologists in recent times that the larger features of the earth's surface have grown from the earliest times, and therefore that the places of the continents and ocean-basins have been substantially permanent. Prof. Dana is largely the originator and expounder of this view, and he has applied it with great skill to the American continent. But while I believe the view is substantially true, I cannot but think that it may be, and has been, pushed too far. It is true indeed that the opponents of the view have attributed to its advocates a strictness in the use of the term ‘permanent’ which they have never urged. It is true that by permanence is meant only permanence of place, not of outline, and that substantial permanence is not inconsistent with very large changes by oscillation, especially at the end of the great Eras. But, making every allowance for such latitude of meaning, there has been, undoubtedly, some confusion of thought and looseness of statement on this subject. We give a few examples.

In the thirty-eighth volume of the Quarterly Journal of the Geological Society is a paper by me on the Corals of the Inferior Oolite, and in the following volume is one on the Corals of the Great Oolite. The forty-first volume of the same periodical contains a supplement to the latter, but to the former no such addition has yet been made. The present communication makes good that deficiency, and is a supplement to it. It contains, besides the description of some new species, additional remarks on others already known, mention of genera about which doubt has been expressed, and the description of one which I consider new. Another genus, Stephanocænia, though well known elsewhere, has up to the present time remained unrecognized as British, and is now introduced on the evidence of two well-marked species from the Inferior Oolite of Gloucestershire. The addition to our Coral fauna of such genera as the above, and of others equally well known which I have also had the opportunity of making known, is of even greater interest than the discovery of new genera and species. Epismilia, Donacosmilia, Cyathophyllia, Adelastræa, Stylosmilia, Rhizangia, Thecoseris, Zeptophyllia, and Enallohelia, form a valuable contribution towards the Coral fauna of this country.

There can scarcely at the present time be a problem more interesting than that of the first appearance of Angiosperms, nor one regarding which there is less trustworthy information at the disposal of the geologist. In attempting to bring together a summary of what is known regarding the earlier forms of this most important division of the vegetable kingdom, I make little claim to originality; nor are such criticisms as I may venture upon entitled to the same weight as if put forward by a trained botanist.

Sir Andrew Ramsay has described the Coal-fields of the Forest of Dean, Somersetshire, and Bristol as outliers of the great Coal-fields of South Wales; there is, however, a marked thinning out in the thickness of the Carboniferous rock in the Forest of Dean as compared with the development of those rocks in South Wales and Bristol. At Clifton, near Bristol, the total thickness of the Carboniferous Limestone is about 2900 feet, at the northern end of the Forest of Dean Coal-field it is about 600 feet.

If we take a general view of the present position of geological science, we are struck by the fact that, although there is substantial agreement amongst geologists on matters relating to the origin of the rocks usually designated as aqueous and igneous, the greatest diversity of opinion prevails with regard to the circumstances under which the so-called metamorphic rocks have been produced. Every fragment of evidence calculated to throw light on the origin of these rocks, therefore, deserves the most careful consideration. Of recent years special attention has been directed to the effects of mechanical energy in modifying the mineralogical and structural characters of rocks originally formed by aqueous and igneous agencies; and a suspicion has been aroused that it is in this direction that we must look for a solution of many of the problems connected with the origin of the crystalline schists. A visit to the Lizard Peninsula of Cornwall during the present summer has convinced me of the immense importance of this view so far as that district is concerned. That portion of the peninsula which lies south of a line drawn from Porthalla on the east to Polurrian Cove on the west is formed.partly of igneous rocks—such as gabbro, greenstone, serpentine, and granite—and partly of crystalline schists. The igneous rocks, in certain places, become foliated and sohistose and sometimes show a definite banding due to a variation in the relative proportions of the different constituents. In other words they present characters which are usually regarded as distinctive of the crystalline schists. There is, moreover, evidence to show that these characters are mainly the result of a yielding to earth-pressure subsequent to the consolidation of the original rock. At the present moment, having just returned from the district, I am unable to treat the subject from a general point of view with any prospect of success; but it has occurred to me that some details with regard to one of the rocks may not be without interest to members of the Association.

Gen. Char.—Corallum composite, with an epithecate base, the corallites subpolygonal, and indissolubly united by the coalescence of their walls. The corallites are sometimes circumscribed, but they are for the most part more or less extensively connected by deficiency of their walls in particular directions, so as to give rise to sinuous rows of serially-united tubes. The calices, like the corallites, may be circumscribed, but are mostly in the form of vermiculate grooves sorresponding with the serially confluent corallites. The calices ire not oblique, nor are the corallites reclined. Mural pores are numerous and well developed. Septa and septal spines are wholly wanting. The tabulaæ are numerous, being simple and complete in the circumscribed corallites, but becoming vesicular in the rows of serially confluent corallites. New corallites are produced by fission.

Two years ago, Mr. Robert H. Scott, F.R.S., Secretary to the I Council of the Meteorological Office, kindly sent me a letter from the Rev. J. G. Nicolay of Fremantle, Western Australia, accompanied by a photograph of a fossil, the original of which had been found by Mr. Davis ‘in the valley of the Arthur River, an affluent of the Gascoyne.’

I readily identified the fossil photographed as the impression of a fish-spine, similar in form, but more highly curved than those discovered in the Coal-measures of Arkansas, Indiana and Illinois, originally described by Prof. Leidy as a fish-jaw, and named by him Edestus vorax in 1855, and later as a fish-spine by MM. Newberry and Worthen (Geological Survey of Illinois, 1870, vol. iv. pp. 350–353, pi. i.).

In his last published volume on the Vertebrata of the Territories,1 Prof. Edward D. Cope has figured and described many new and remarkable forms of the Order Ungulata from the Eocene of Wyoming. The most important and interesting among the numerous species described being the genus Phenacodus, of which the nearly entire skeletons of two species have been discovered, namely P. primœvus, represented in our plate (Plate II.) and P. Vortmani.

Mr. W. Carruthers, F.R.S., lately called my attention to the resemblance between some drawings I was showing to him of Hyalostelia fasciculus, M'Coy, sp., and the supposed fossil plant, described and illustrated by Dr. Henry Hicks, F.R.S., in the Geological Magazine for 1869, Vol. VI. p. 534, PL XX. Figs, la-e, under the name of Eophyton? explanatum.

In December last Dr. C. A. White, Palæontologist to the U.S. Geological Survey, sent me a small packet of siliceous Ostracoda, obtained by dissolving in dilute acid some pieces of an impure limestone from the Jurassic “Atlantosaurus Beds” near Cañon City, Colorado. These strata are of freshwater origin; and, besides the wonderful Dinosaurian and Mammalian fauna, which Prof. O. C. Marsh has published, they contain, Dr. White informs me, Unio, Limnæa, Planorbis, and Valvata, all of modern types. In the impure limestone with Ostracods, and in associated layers, these Gasteropods are found also in a silicified state, and the Dinosaurian fossils occur both above and below them.

In a paper read before the Birmingham Philosophical Society in 1882, it was announced by Professor Lapworth that the discovery of fossils in some shales underlying the productive Coalmeasures of Warwickshire, and coloured on the Geological Survey Map as Coal-measures, proved that these shales must be of Cambrian age (Lower Silurian of the Geological Survey). As the true age of these shales had for many years been a debateable question, Professor Lapworth's discovery was of considerable interest, and has led to an important alteration being made in the map, the supposed Lower Coal-measures and Millstone Grit having both been now relegated to the Lower Silurian (Lingula Flags). It may be of interest, before entering on the description of these beds, to trace shortly the history of the error in their classification.

The Carboniferous Ostracoda here described are from the deep Gayton Boring, near Northampton. Hand-specimens of the rock, obtained by H. J. Eunson, Esq., F.G.S., were given to us by R. Etheridge, Esq., F.R.S., some months ago; and Mr. Eunson kindly gave us another piece lately.

To explain the situation of the bore, as well as the position of the Carboniferous strata in it, we quote as follows from Mr. H. J. Eunson's paper “On the Palaeozoic Eocks beneath Northampton,” in the Quart. Journ. Geol. Soc. vol. xl. 1884, p. 485, etc.:

“The second trial took place near the village of Gayton, five miles south-west of Northampton, not far from the Banbury-lane crossing of the L. and N.-W. Eailway, about two miles north-west of Blisworth Station (see Ordnance Map 52 S.W.).

I Heard this communication read at the Geological Society in June last, and I made some remarks upon it which are noticed in the Proceedings of the Society. A considerable portion of the paper consisted of criticisms of some of my work which appeared in the British Fossil Corals (2 ser. Pal. Soc. part ii. Nos. 1 and 2, 1869–70). Some specimens were exhibited, in the author's absence, which were presumed to afford evidence of a satisfactory kind. But it was observed that the very imperfect and bad condition of the fossils did not substantiate the author's statements.

Many years since, Mr., now Prof., Ralph Tate gave me a small slender coral, which he had obtained from the Pea Grit of the West of England. I had just completed the Supplement to the British Fossil Corals, Pal. Soc., so the fossil has remained undescribed.

Dr. Bonney having been so kind as to examine microscopically and describe a collection of crystalline rocks which I made in the vicinity of Assouan on the Nile, I have prepared the following notice of the geological conditions, to accompany his descriptions, referring, however, to the notes on the locality given in my paper in the Geological Magazine for Oct. 1884. Reference may also be made to the paper of Lieut. Newbold in the Journal of the Geological Society, vol. iv., and to that of Mr. Hawkshaw in the same journal, vol. xxiii. Lartet has given in his Geology of Palestine a summary of the observations of Russegger, Rivière and Figari Bey on the crystalline rocks of the Nile, and the allied rocks of the Sinaitic Peninsula have been described by him, by Bauerman and by Holland, and more recently by Hull. All these authors have given, more or less distinctly, a series of gneisses and micaceous and hornblendic schists associated with intrusive granites and diorites as the oldest rocks of these districts, and succeeding these in geological age, certain slates and associated rocks, with porphyry and basanite in beds and veins.

The meeting of the British Association in Montreal gave different Irish geologists facilities for examining the Archæan rocks of Canada and the States, while since then they and also American geologists have had opportunities for studying the Irish Metamorphic rocks; it may therefore be allowable to give an epitome of our knowledge in regard to the latter.

Much interest has been recently aroused in the exploration of the caves of the Vale of Clwyd, partly by the enthusiasm of the principal promoter of the investigation, Dr. Hicks, but chiefly owing to the inferences he has drawn from the observations made. When reading the Report of the British Association Committee for the Exploration, of which he was Secretary, he assumed the entire responsibility of those theoretical deductions. In these, however, he was supported by all the speakers who followed him on the subject, including the other members of the Committee excepting myself. He had previously anticipated the report by the announcement in Nature of his discovery of Pre-Glacial Man in the Vale of Clwyd. I therefore ask leave briefly to state my reasons for differing from his conclusions.

In any inquiry into the history of the earth as a whole, we are met at the outset by a serious difficulty. In human affairs a general view of history, not confined to a single country, would be practically impossible, were we ignorant of the relations of the various eras from which different races reckon their dates: thus, it would be impossible to write a connected account of the history of Europe in the classical period were it not possible to determine the relation of the Olympian era to that dating from the foundation of the city of Eome. Yet the supposed case is not unlike that to which the geologist addresses himself when he endeavours to make a connected survey of such widely-separated regions as Europe, India, Australia, and America.

In the supposed case of the Greek and Roman eras, there are numerous points of contact, principally dates of battles, which, having been recorded by both nations according to their own system, enable us to compare the two, and so to determine what would be the date of any event, recorded by the one, had it been recorded by the other. But in geology we have no such points of contact; there is a very general tendency to regard any two series of beds, in which a few fossil forms specifically identical are found, as of contemporaneous origin. That this view is erroneous, and that it would be nearer the truth to say that two widely-separated beds, in which the same forms are found, could not be of contemporaneous origin, was long ago pointed out by Forbes and Huxley, the word homotaxis being invented by the latter to express the relation existing.