The general structure and mode of growth of coral reefs and islands is well understood; but there is one attendant circumstance of considerable geological interest, to which, so far as I am aware, attention has never been called. This is the peculiar stratigraphic relation of the different strata in the reef to their chronological equivalents in the deposits of the surrounding ocean; a relation due to the comparatively rapid growth of the reef as a whole.

The materials for a classification of the later Pleistocene deposits of Cornwall are so voluminous that it was found impossible to embody them in a single paper. Having submitted to the Geological Society a general classification with such notices of the deposits as seemed necessary to show the grounds whereon it was based, I purpose in the following paper to complete the notices of deposits. As an apology for the amount of compilation thus rendered necessary, I must plead the object of the papers, viz. to place in one view all that has been written on the subject, as references alone would entail more time and trouble in looking up than many readers would be disposed to concede.

A short time ago, whilst examining and appending the names to a number of specimens of fossil fish in the collection of the Bradford Philosophical Society, which are being arranged and exhibited in the new Corporate Museum in that town, I came across the spine which is the subject of this notice. It is from the Black-bed Coal at Dudley Hill, near Bradford.

During the year 1873, it was my good fortune to be one of a party who, in the course of an exploration of the Andaman and Nicobar Islands, were enabled to spend a few hours on the detached volcanic islands of the Bay of Bengal, which are known respectively as Barren Island and Narkondam. The time at our disposal did not admit of our making as thorough an examination as we should have wished, but there was sufficient opportunity for testing the accuracy of the statements regarding the islands which had been previously published, and also for making a few original observations.

This cast indicates a subfusiform shell with a somewhat elongated conical spire, but the apex is imperfect: volutions contiguous and convex; the body-whorl gradually tapering to a somewhat acute base.

Among the Conchifera transmitted by M. Verbeek, is a specimen of Cyrena. The shell is certainly from a very modern formation, as it retains its translucency and traces of a pale buff colour externally.

Hitherto, exposures of the junction of the Bunter formation with the Keuper, in the Nottingham district, have shown the brown sandstones and red marls of the “Waterstones,” with a band of dolomitic conglomerate at the base, resting directly on an eroded surface of the Bunter Pebble Beds. Recently, howeve, between these formations there have been observed to intervene certain deposits that agree both in mineral composition and in physical characters with the white sandstones and conglomerates, known as the “Basement Beds,” that form so important a feature in the Keuper of the West Midlands.

A somewhat detailed description of the surface deposits of North-eastern Iowa, with references to observations of a similar nature in other localities, and some general conclusions, was read by the author before the American Association at its St. Louis meeting, and is printed in the Proceedings for 1878. Since the preparation of that paper additional observations have been made in the same region; and some other localities, mainly in the State of Illinois, have been visited. A general section has been made across the northern portion of this State, from the Mississippi on the west to Lake Michigan on this east, at about 42° N. lat. A like section has been made the greater part of the length of the State from north to south, at about long. 89° W. from Greenwich. The data employed in the construction of these sections were chiefly derived from personal observations on the surface, in channels of erosion, and in artificial excavations on the surface, in channels of erosion, and in artificial excavations; but use has also been made of observations of other persons, collected by means of extensive inquiries from, and correspondence with, local geologists and others. In Iowa a formation, believed to be distinct from any previously described, has been discovered, and a rather anomalous distribution of the member considered to be the equivalent of the loess has been brought to light. Several åsar, which seem to be homologous with those of Scandinavia, have also been traced over some distance.

Among the many relics of Palæozoic life-forms which the Carboniferous formation has yielded to the palæontologist, none is more remarkable than “Scouler's Eidothea,” or the Eurypterus Scouleri of Hibbert.

A quarter of a century ago it was a disputed question whether it the Old Red Sandstone was a separate formation or not. About that time, or a few years later, the subject. engaged the attention of the Geological Section of the British Association.

To ascertain the most recent movement to which a country has been subjected, and by careful comparison with the past to discover what insensible changes are now progressing, is of the utmost importance in approaching its Quaternary History.

The rocks I propose to describe in this paper belong to that great metamorphic series which occupies so large a portion of the north of Ireland, extending over most of the counties Tyrone, Londonderry, and Donegal. For the present I shall confine, my observations principally to that portion of them situated about the central parts of Tyrone, from the vicinity of Omagh eastwards and north-eastwards towards Slieve Gallion. This district has “Geological Report on Londonderry and parts of Tyrone and Fermanagh”; but as, during the progress of my work for the Geological Survey, I have had opportunities for a very detailed examination of it, I beg, briefly, to offer some further remarks and conclusions.

The great geological interest which attaches to the fossil remains of the Musk-ox or Sheep (Ovibos moschatus, Blainv.), found in British Pleistocene deposits, and the few instances hitherto recorded of their occurrence (together with a recent discovery brought to my notice), have suggested to me the desirability of a brief enumeration of them.

As the Carboniferous rocks form a framework around the Silurian mountain country, so do the Permian rocks for considerable distances lie as an outer flat and bevelled edge to the slightly raised Carboniferous frame, the edge indeed overlapping the frame itself along the west coast-line between St. Bee's Head and the Duddon Estuary.

Joining a foreign geologist, who was staying here a while last summer on his journey to the North, I followed the old shoreline or sea-level of Bredviken, cut in the solid rock, and extending along the north part of the island of Tromso, near the sound bearing the same name. When, at the end of that line, about Oerendalen, we threw a glance at the low ground beneath, named Skatoeren, this appeared furrowed with a series of natural ditches, stretched horizontally and parallel to the present coast. Seen from above, they were marked very sharply and distinctly. This attracted my attention, the more so as I had often there, and as frequently traversed the plain, without having discovered the fact. We accordingly went down on the low ground to examine the matter more closely, but it did not appear there so distinctly, as might be supposed when seen from above. But after a more searching examination, we succeeded in detecting a series of more or less distinct and parallel furrows. Our time being limited, however, we could make no closer inquiry for the moment; but as I considered the matter worth more minute studying, I returned to the place a few days afterwards.

Since the publication, in the Quarterly Journal of Science for July, 1876, of an article on the Indian Diamond Fields, in which the writer, Captain Burton, does not appear to be aware of what has been done in these Colonies towards adding to our knowledge of the geological history of the diamond, I have been induced to re-write a paper, jointly prepared by the late Professor Alex. M. Thomson, of the Sydney University, and myself, and read before the Royal Society of New South Wales on the 7th December, 1870; and to incorporate with it a series of my own papers (of which the above was merely a summary), which appeared in the “Sydney Morning Herald” previously to that date. I shall confine my remarks to the mode of occurrence of the diamond in New South Wales, as the late Rev. W. B. Clarke has, in his valuable and interesting Presidential Addresses to the Royal Society of New South Wales in 1870 and 1872, almost exhaustively treated the subject, as far as regards our present knowledge of the diamond all over the world.

The next appearance of the older lead is at the “Rocky-ridge,” where the river, after running northerly for three-quarters of a mile, along the strike of the metamorphic beds, turns abruptly to the west. This ridge is a basalt-capped hill on the north side of the river, running in a north-west direction; it is about a mile long, with a bold rocky escarpment on its west side, facing the Sandy or Cudgebeyong Creek. Some tunnels have been driven in, and shafts sunk on this hill, and tolerably rich deposits of gold were found, but never followed out.Only in the southern half of the hill have diamonds been found(all more or less spotted).The drift is remark-able for the number and size of the agates it contains.The northern half of “the ridge” is underlaid by another outlier of the before-mentioned doubtful purple conglomerate, into which some tunnels have been driven in the western escarpment.The basalt is merely a fringe here, resting against the flank of the conglomerate, in which a small quantity of nuggetty gold was obtained;and form one to two inches thickness of lignite, or carbonaceous clay, is seen between it and the bottom of the basalt. Tte basali is intersected by numerous veins of a mineral allied to kaolin. The purple con-glomerate is similar in character to that near “the flat”and contains, on some of the joint faces, smll spherical crystalline aggreations of chalybite(carbonate of iron).At the extreme north ead of “the ridge”are great quantities of ironstone and conglomerate, but, from their Carbpniferous series, which is largely developed further north.The first diamonds which found their way to Melbourne were obtained.

Notwithstanding the distinct assertion by more than one geologist1 of the intrusive character of the serpentines of these districts, some uncertainty seems to exist on this point and still more as to the original character of the rock. Hence the result of my examination of a few localities, and of my subsequent studies of the rocks then obtained, may be of sufficient interest to justify publication.

In last month's Geological Magazine there is much (by three writers) that bears upon the Devonian Question, and I would now add a few words on the same subject, which is of the greatest interest to me.