Amongst the undescribed sponges from the Cambridge “Coprolite” bed, which have come under my notice, is the beautiful hexactinellid that forms the subject of this communication.

Aspect of Newfoundland.—It has been suggested that the so-called glacial effects which are universally seen in temperate, and even in tropical regions, may in many cases have been due to an ocean on which great icebergs floated. These, as they moved from point to point (like huge pepper-castors), strewed broadcast boulders and detrital matter, such as are now to be seen over an area like that of Russia and parts of North America. The effect of the force of impact of these tremendous masses has also been dwelt on, and the way in which they could grind, smooth down, or rub up the surface of a submerged area, has also often been referred to.

The foregoing paper was sent to me by Dr. Linnarsson, along with a fine collection of Swedish Graptolites; and I am happy to be the medium through which his interesting observations appear before the English public. With singular acumen, the distinguished Swedish geologist has unravelled the intricacies which beset the study of the distribution of the Graptolites in past time; and his results are of peculiar importance and value. Some of these results, in so far as they especially bear upon British Geology, may just be indicated here.

That the latest movement of the south-east of England has been one of depression is evidenced by the numerous “submerged forests” which occur at intervals round the coast, ranging downwards, not only to half-tide level, but to beyond the lowest ebb; and therefore not explicable merely on the hypothesis of sheltering sandbars, or lines of dunes, even where such can be shown to have existed.

This genus was founded by Mr. Carruthers to include those compound forms of monoprionidian Graptolites in which the polypary is unilateral, growing from the initial point in one direction only. There can be no hesitation in regarding it morphologically as a branching Monograptus; its mode of development, the characters of its hydrothecæ, and its geological distribution, all pointing unmistakably in this direction.

In a recent Number of the Geological Magazine Mr. Burns assumes that Geologists in general seem to be satisfied with Mr. Croll's theory of the motion of glaciers because they do not write in refutation of it. I am convinced that with some at least it requires no refutation, and its very obvious inadequacy is to them a sufficient reason for passing it over in silence. There cannot be wanting men who, appreciating the difficulty of the problem, can only smile at such a “solution.”

It has long appeared to me that much remains to be said on this subject. When Mr. Croll's papers on the Physical Cause of the Motion of Glaciers appeared in the Philosophical Magazine for March, 1869, and September, 1870, I felt that, though his theory was certainly ingenious, and his statement of it clear and masterly, these papers were far from affording a satisfactory solution of the problem of which they treated. I waited, fully expecting that Mr. Croll would supplement and modify his theory, but he has not done so to my knowledge. Geologists in general seem to be as satisfied with it as he is himself, and on all hands they appeal to it as supporting them, whenever they treat of glacial phenomena, even when, if true, it shows their theories to be vain. A rather conspicuous instance of this occurs in the Geol. Mag. for October of last year, in an interesting paper by Mr. Goodchild on Coums. In that paper Mr. Goodchild commends “a proper appreciation of Mr. Croll's theory”; but I am persuaded that a proper understanding of it would have caused him either to renounce that theory or his own on the origin of Coums. I have thought it time, therefore, to place on these pages my criticisms and difficulties for the consideration of geologists, even if, as is unfortunately too likely, I have little new to advance.

Igneous Action and Metamorphism.—I have already referred to the fact that igneous eruptions were frequent during Palæozoic time. As far as there is any evidence at present, they do not appear to have taken place during the Cambrian Epoch either in Europe or in North America. In Europe contemporaneous tuffs or ashes are found for the first time in the succession in the Arenig rocks; and in America about the same period, or perhaps a little earlier. By referring to the Table, p. 156, it will be seen that the contemporancous traps also occur only in the areas which had undergone most depression, or where the greatest amount of sediment had accumulated. Sir J. Herschel has urged as a reason for this that the crust after a continued period of depression would descend to a point where the heat would be sufficiently great to melt it through, or to weaken it; and that as a consequence fractures would take place, and there would then be a corresponding rising of heat and fiery matter from below, to that of the accumulation of the sediments.

Coast Ice of Newfoundland.—Icebergs have an advantage over coast-ice in their imposing appearance, which has perhaps been in part instrumental in raising them to the high position which they now occupy as workers of Geological changes. Many Manuals of Geology, and many diagrams drawn to illustrate the same science, have oft-times portrayed a well-known flat-topped berg, carrying a rock, in the Antarctic regions; but neither books nor lecture-diagrams, taken collectively, give any adequate idea of coast-ice as a similar agent. From what I have seen of coast-ice and of its effects. I feel persuaded that it is an agent of at least as great, if not of greater universality than either glaciers or icebergs, and taken as a whole perhaps also as an agent of equal power. Of the various forms of sea-ice known as “berg-ice,” “floe-ice,” “pack-ice,” and the like, the portion I would more particularly draw attention to is that variety which forms a narrow belt along the shore, known in Greenland as the “Ice-Foot.”

No. 4.—The cause suggested under this head was the favourite theory of Sir Charles Lyell. That the existing climates are materially influenced by the distribution of land and water, and by the direction of the great ocean currents, physicists and geologists are agreed. It was the view, however, of Sir Charles, that these conditions were of themselves alone adequate to account for all changes of climate which the earth has undergone, though in his latest editions of the “Principles of Geology” he admitted that other causes have probably contributed. In this work he gave imaginary representations of such a distribution of land and water over the globe as, in his view, would produce the extreme of heat and the extreme of cold. In that intended to represent the extreme of heat, the land is all collected in low latitudes on either side of the Equator, so that the higher latitudes and polar regions are occupied entirely by the ocean; while in that intended to represent the extreme of cold, these conditions are reversed.

B. Mountain Limestone Proper.—Both the Hecla Hook and Liefde Bay strata, and the strata included in the foregoing division, consist of fresh-water formations, devoid of any trace of marine fossils; which proves that Spitzbergen, during the immense period of time in which these strata were deposited, formed a considerable continent. Later, however, these circumstances were altered, inasmuch as that part of the globe was again covered by sea, from which, with only an inconsiderable, perhaps local, break (the strata of the Coal-formation in Bell Sound), during a long sequence of geological periods, strata of great extent, containing marine fossils, were deposited. The oldest and most extensive of these strata belong to the Mountain Limestone formation, which in this part of the polar regions is specially developed and rich in fossils.

Polypary four or five inches in length, straight or very slightly curved, attaining a maximum diameter of one-twelfth of an inch. Hydrothecæ short and broad cups, with subquadrangular section, 20 to 24 to the inch, without overlap, inclined at an angle of about 45°; outer edge convex distally, proximally impressed; apertural margin deep, concave, at right angles to the general direction of the theca; denticle triangular and inornate.

The numerous excellent observations which have been made in recent years relative to the Palæozoic rocks in different countries in the Northern Hemisphere, require that we should now and again attempt to summarize the results obtained, and by that means bring before the mind more clearly any advance in our knowledge of past changes which has been made, as well as note those blanks which are still left for future investigations. In these considerations I cannot attempt to treat fully the various observations made, but I will endeavour to notice the chief results, or those points upon which new light seems to have been thrown.

Of all the physical features of our continent, that which most powerfully arrests the attention is the noble chain of the Alps, with its wide-spreading system of subordinate mountain-ranges; and among the series of grand events, which by the researches of the geologist are demonstrated to have taken place on this our own portion of the globe, there are none more striking and conspicuous than those manifestations of subterranean forces to which the vast mountain-masses in question owe their origin.

Ice and Bell Sounds are two large fiords opening out on the west coast of Spitzbergen, which cut deep into the country, both in an easterly direction towards Stor Fiord, and in a northerly direction towards the south part of Wijde Bay. The shores of the Sounds are for the most part occupied by high mountains, precipitous towards the sea, nearly free from snow during the summer, whose sides, being bare of vegetation, offer the observer an uncommonly favourable opportunity for studying the geological structure of the rocks. Within an excecdingly limited space one meets here with a succession of strata belonging to a great many different geological periods, and rich in fossils, both of the vegetable and animal kingdom.

In a paper on the above subject, that appeared in the GeologicalMagazine for December, 1875 (p. 583), the author, Mr. S. Allport, F.G.S., objects to the introduction of additional rock names. With this observer I agree that there are many ingenite rock names which it would be satisfactory to get rid of; seeing many varieties and subvarieties of rocks to which names are given have no permanent characters; while in numerous cases the same rock is called by different names. Still, as a geologist, I would suggest, that in some cases new names are absolutely necessary, if we would impart our increasing knowledge to the general public; for instance, among the granitic rocks, the subject that has led to Mr. Allport's remarks.

The recent discovery of fossil fishes in the Carboniferous beds of North Devon appears of sufficient importance to require that the facts connected with it should be placed on record.

In a paper, read before the Geological Society of London (June 25, 1873), “ On the Glacial Phenomena of the Long Island or Outer Hebrides,” Mr. James Geikie mentioned the occurrence of two descriptions of stony clay in the Long Island. The first of these deposits or “Bottom Till” occupies the low ground of the island, and is derived from the disintegration chiefly of gneissie rocks, and so far as observation went proved to be unfossiliferous. The other deposit was found in the north of Lewis, along the coast, and consists of two beds of unstratified stony clay containing fragments of shells, the lower resting on rock in situ.

It is now more than eleven years since I ventured to take a part in the discussion then raised by Professor Ramsay having lately published his celebrated theory of the Erosion of Lake-Basins by the lower ends of Glaciers, where they may have formerly expanded over a more level country, beyond the confines of their parent valleys. It appears to be admitted that a great many lakes lie in positions where it would be natural to suppose them so formed, if only glaciers could have possessed the crosive powers necessary for the purpose. The positions of the deeper parts of the lakes also accord well with the theory.

In framing a theory attributing the terraced form of limestone outcrops in the Yorkshire Dales to glacial erosion, Mr. Goodchild was doubtless prepared to encounter much adverse criticism. If in this communication I venture to differ from his views, he will believe that it is in no captious spirit. The district in Northumberland from which I write supplies materials for criticism of the most relevant kind, presenting as it does the same series of Carboniferous rocks cropping out in surface features closely allied, and subjected in the Glacial Period to the pressure of the same ice-sheet. The terraces of Wensleydale, too, are not wholly unfamiliar to me.