Sp. Chars.— Shell ovato-elliptical, or suborbicular, slightly convex in the median line, Flattended towards the margin; ears small, pointed, depressed, tringular, subequal, conate, their apices elevated above the level of the general periphery of the shell, both separated from the body of the shell, with their outer edges convex; umbones simple, straight, and pointed; muscular impression large, and situated near the beaks and posterior margin; shell thin and delicate; surface ornamented with numberous close, fine, concentric lines.

Palæontology, like most other sciences, has attracted a large number of students since the first pioneers cleared the way for inquiry and brought the fossil remains into something like connected order. This increase in the number of inquirers has borne fruit in the immense variety of fossil remains that are scattered about in museums and private collections, the variety being now so great that it has become almost impossible for one person to study the whole of them, in consequence of which the majority of students confine themselves to the fossils of one formation or to the remains of a natural order, as Invertebrata or Vertebrata. Here, again, the application of a number of investigators to one distinct branch is bringing a further increase to our knowledge in that branch. Take the case of fossil fishes. It was quite possible twenty or thirty years ago for the great palæontologist Agassiz to describe and figure what, as the result of seventeen years of close study, was then known of the fossil fishes of all formations; but the stimulus that resulted from the publication of his work has piled up the list in a wonderful manner, so that it would be well-nigh impossible for any ordinary palæontologist to describe them all now in anything like a satisfactory way. This great amplification necessitates inquirers to confine themselves to the fish remains of a single formation, or to a particular part of the fish, as for example, the teeth.

In his letter to the Editor, inserted in the last Number of this Magazine (p.332), Mr. Mallet says he is “compelled to repeat” the statements he had persistently made, and I had more than once denied, as to my having, “in almost all my writings,” upheld “the moribund thin crust and liquid nucleus theroy”and “ Hopkins's fiery lakes.” He defends himself from the charge of having “misapprehended,” as was suggested in an Editorial foot-note to his paper, or, as I more truly phrased it, “misrepresented,” my views on these subjects, refusing to be bound by what I may have “written in the scattered magazine articles ” to which he was referred, on the plea that “an author's notions are usually gathered from his acknowleged systematic works.”

In 1863 the skull and a portion of the skeleton of a large extinct species of Ox (B. primigenius), which had been found in the peat of the Cambridgeshire Fens, and which apparently had been killed by a celt, was placed in the Woodwardian Museum at Cambridge. At the time of its deposition there a portion of the flint remained firmly fixed in a fracture in the frontal bone, being partially retained in sitû by a mass of peat: as, however, this peat gradually dried, it crumbled away, and the celt became loosened and displaced; moreover, some small fragments of bone fell away from the margin of the wound, so that in its present condition the specimen merely exhibits an irregular fracture in the forehead, in which a fragment of a flint implement lies loosely; but it no longer furnishes conclusive and positive evidence to prove that the fracture was actually caused by the celt which occupies it.

The only mention hitherto, so far as I know, of the occurrence of Starfish in British Devonian rocks is that given by Mr. Etheridge in his list of Devonian fossils (Quart Journ. Geol. Soc., vol. xxiii. p. 619), viz. Protaster, sp., and Palæaster, sp., from the Pilton beds of North Devon; therefore the discovery of a species in South Devon rocks may not be without interest.

In a letter to Nature for 14th May, 1874, Mr. Belt has expressed his belief that the presence of shells in glacial deposits, at whatever elevation they may be found, does not necessarily constitute a proof that the land has been depressed to that extent relatively to the level of the sea; but that in such cases as those of the drifts of the basin of the Irish Sea the shells occur in their present positions because they were thrust thither out of the bed of the sea by the ice-sheet which was advancing from the North.

In the late Dr. Falconer's Palaeontological Memoirs so ably edited by Dr. Charles Murchison, F.R.S., a masterly and critical examination is given of the European Pliocene and Post-Pliocene species of the genus Rhinoceros, from which we venture to extract the subjoined introductory remarks.

An ordinary glacier descends in virtue of the slope of its bed, and, as a general rule, it is on this account thin at its commencement, and thickens as it descends into the lower valleys, where the slope is less and the resistance to motion greater. But in the case of continental ice, matters are entirely different. The slope of the ground exercises little or no influence on the motion of the ice. In a continent of one or two thousand miles across, the general slope of the ground may be left out of account; for any slight elevation which the centre of such a continent may have will not compensate for the resistance offered to the flow of the ice by mountain ridges, hills, and other irregularities of its surface. The ice can move off such a surface only in consequence of pressure acting from the interior. In order to produce such a pressure, there must be a piling up of the ice in the interior; or, in other words, the ice-sheet must thicken from the edge inwards to the centre. We are necessarily led to the same conclusion, though we should not admit that the ice moves in consequence of pressure from behind, but should hold, on the contrary, that each particle of ice moves by gravity in virtue of its own weight; for in order to have such a motion, there must be a slope, and as the slope is not on the ground, it must be on the ice itself: consequently, we must conclude that the upper surface of the ice slopes upwards from the edge to the interior. What, then, is the least slope at which the ice will descend? Mr. Hopkins found that ice barely moves on a slope of one degree. We have therefore some data for arriving at least at a rough estimate of the probable thickness of an ice-sheet covering a continent, such, for example, as Greenland or the Antarctic Continent.

This very handsome rock forms almost the whole surface of the Island of Lambay and of the adjoining coast, a few miles to the north of Dublin Bay. It is also laid open in the railway cutting at Donabate Station; and has received considerable notice owing to its intrinsic beauty as an ornamental stone, and its proximity to the Irish metropolis. I am informed by Kev. Dr. Haughton that he has identified specimens from the tessellated pavement of St. Kevin's Church, Glendalough, of the seventh century, which were submitted to his in spection by Sir W. Wilde. A polished table, together with a large block presenting two sides cut and polished, are placed in the gallery of the Royal College of Science in St. Stephen's Green; where, to those familiar with the marbles of Italy and Greece, the appearance of these specimens cannot fail to recall the green porphyry (Marmor Lacedæmonium viride) so largely used in ancient decorative works of art, and often reset in modern ones, the source of which is in the neighbourhood of Sparta and Marathon. The two rocks, however, though resembling each other in appearance, are essentially distinct as regards mineral composition, M. Delesse having proved that the Grecian porphyry contains augite as an essential, and is apparently a porphyritic basalt, while the Irish porphyry is altogether destitute of this mineral. As regards geological age, the Lambay porphyry appears to have been intruded amongst the Lower Silurian rocks at a period antecedent to that of the Old Bed Sandstone, as this latter formation overlies the porphyry without appearing to have undergone any alteration along the surface of contact.

The specimen (No. 37,958 of the British Museum Collection), which forms the subject of the present notice, is from the Blackband Ironstone of Airdrie, and, I understand, from the same bed which yielded the first known specimen of Anthracosaurus Russelli. The fossil is unfortunately very imperfect, though it displays a considerable portion of the body of a large fish lying on its right side. Both the head and the caudal extremity, however, are gone, nor is the ventral margin shown; but the line of the back is pretty nearly intact, and is seen to be bordered by the long dorsal fin characteristic of Phaneropleuron and of Uronemus. What remains of the body shows a confused mass of ribs, spinous processes, and inter-spinous ossicles, compressed against a groundwork of what are apparently large and very thin rounded scales. The specimen, measuring 15½ inches in length, by 5½ inches in breadth at its broadest part, presents thus a considerable part of the abdominal, with the anterior part of the caudal region of a fish, which, when entire, must have been in all probability more than two feet long.

Polyzoary calcareous, sessile, and encrusting, forming systems of small circular discs, the upper surfaces of which are marked with radiating ridges, upon which the cells are carried. Each disc is attached by its entire lower surface, slightly convex above, with a central non-poriferous space, round which a number of radiating poriferous ridges occupy an exterior slightly elevated zone. Cells forming a double series on each ridge, immersed, with rounded mouths, which are not elevated in any part of their circumference above the general surface.

Gen. Char.—Corallum aggregate, massive, composed of hexagonal corallites, which have distinct walls, but are firmly united with one another. Septa well developed and close-set, but short and not nearly reaching the centre of the theca. A row of large and closely-approximated mural pores between each pair of septa. Tabulæ horizontal, not vesicular or infundibuliform, apparently incomplete. Epitheca unknown. No coenoenchyma.

In many places in Ireland, but conspicuous in the S.E. portion, there is a Glacialoid drift (that is, a drift very similar in aspect to some of the typical Glacial drift). This drift will be found in places above the shelly drifts of Wicklow and Wexford, and has led Prof. Harkness, F.R.S., to believe that in those counties there is evidence for two distinct periods of glacial drifts, one below and the other above the shelly drift. His classification has been adopted by Mr. A. Bell and others; still there does not appear to be evidence in Ireland for two distinct ages of glacial drift, separated by an interval, represented by sub-aqueous accumulations (sand, gravel, marl-clay, &c.), and the reasons for this conclusion will be given in this paper.

Spec char.—Corallum ramose, the branches cylindrical, of a diameter of from a line and a half to two lines, dividing dichotomously at intervals of about half an inch, but not anastomosing. Corallites oblique to the surface, with exceedingly thick walls. Calices extremely minute, about one-eighth of a line in their longest diameter, sub-circular, transversely oval, or sub-triangular, level with the surface, and having the lower lip hardly or not at all prominent. Intervals between the calices proportionately very wide—usually about half a line.

The greatest extent of the displacement of the earth's centre of gravity, and consequently the greatest rise of the ocean resulting from that displacement, would of course occur at the time of maximum glaciation, when the ice would be all on one hemisphere. But owing to the following circumstance, a still greater rise than that resulting from the displacement of the earth's centre of gravity alone might take place at some considerable time, either before or after the period of maximum glaciation.

In the Geological Magazine of last October I have noticed the occurrence of zinc in small quantities in the White Limestone (Chalk) of the Co. Tyrone, and also in the overlying basalt. When that paper was read, exception was taken to the latter part of it, on the ground that-the metal in question had never been known to exist in rocks of igneous origin; but as my analysis seemed perfectly trustworthy, I saw no reason to modify it on the objections then put forward. Since then, whilst making an investigation.– with a different object–on a specimen of basalt from another locality in the neighbourhood of that whence the one originally examined was obtained, I succeeded in again finding zinc in it; and I think it well to mention the fact now, as an addendum to, and as confirming my former statement.

Carboniferous Period.—The Lower Carboniferous rocks, both of the North of England, of Scotland, and of Ireland, afford examples of contemporaneous volcanic action of considerable intensity. The so-called “toad-stones” of Derbyshire, and the great sheets of melaphyre, porphyrite, and ashes of the central valley of Scotland, forming the Kilpatrick, Campsie, and Dairy Hills, appear to have been erupted over the bed of the same sea as that in which were poured out similar materials in County Limerick, forming the well-known Carboniferous volcanic rocks of “the Limerick Basin.” These rocks have been already so fully described by several observers, that I shall confine myself to a very short description, such as is essential to the brief history of volcanic action which I am here endeavouring to draw up.

A Glance at the map stows that within a short distance of the town of Nottingham there are Coal-measures, Permian, Bunter, keuper, and Lias rocks. A paper therefore on the district must of necessity be somewhat lengthy, but perhaps of all the greater interest as dealing with the border-land of the Palæozoic and Mesozoic epochs. The generally supposed unconformability between the Permian and Triassic rocks does not appear to exist in this area; while that between the Permian and the Coal-measures is very considerable.

Some specimens of dark olive-grey mudstone from Peeblesshire, collected and shown to me by Mr. D. J. Brown, contain several internal and external casts of small bivalved Entomostraca.

Having been engaged for many years in collecting and studying the corals of the Mountain Limestone of Scotland, I propose, in the present communication, to describe some of the new species which have come under my notice. Some of these were discovered in a thin bed of shale from five to nine inches thick, which overlies the low post of limestone in Trearn Quarry, near Beith, Ayrshire. Indeed, this horizon throughout Great Britain may be safely said to be the zone in which simple corals existed in greater abundance, and attained greater dimensions, than in any other section of the Mountain Limestone. There are a few forms found in the upper members of the period. So far, however, as my investigations have gone, these are limited both in genera and species; and, with only one or two exceptions, are all more or less simple in their organization. It is not my intention at present to enter into any elaborate stratigraphical arrangement of beds, or classification, or distribution of the different genera or species. That will form matter for a memoir, in which I hope to delineate not only the almost imperceptible gradation from one species into another, but also the persistent modifications that occur between the different genera. Indeed, those modifications are so constant, that it often becomes difficult to say where one genus begins, and its next ally ends. This is a result that can only be safely attained by examining an extensive collection of specimens, all of which must be sectioned with great care. From my own personal observations, assisted by my friends, I shall be able to note the stratigraphical distribution of the genera and species throughout the three kingdoms. Such a memoir is a great desideratum; and it can only be prepared from personal investigation and examination of sections. Only thus can we ascertain in what condition the genera and species are found.