Many attempts to revive and improve the classification of our rock-groups have been made from time to time, and the International Geological Congress will doubtless make a further effort in the same direction.

The Lambourn river, in Berkshire, which rises from springs in the Chalk hills between Up-Lambourn and Chipping-Lambourn, and receives other springs lower down, has been dry for about six miles between Lambourn and Shefford this winter; and the Winterbourn, a smaller stream, which rises close to the Ford, at Chapel Copse on the Leckhampstead estate, near Chieveley, has also been dry from its source to near Bagnor (nearly four miles), where it joins the Lambourn.

In a paper lately published in the “Neues Jahrbuch” (Band i. 1884), Herr W. Dames, of Berlin, has made some observations “On the Phyllopod-nature of Spathiocaris, Aptychopsis, and similar bodies,” met with in strata of Silurian, Devonian and Carboniferous ages in Europe and North America, and described by Barrande, Salter, M'Coy, Meek, Hall, Clarke, Jones, myself, and others.

In 1822, just sixty-three years ago, Mrs. Mantell found the first tooth of a new and remarkable reptile (afterwards known as Iguanodon), imbedded in a mass of coarse conglomerate, which had been brought as ‘road–metal’ from one of the quarries in the Wealden formation of Tilgate Forest.

The arrangement of a considerable collection of Cretaceous corals in my own cabinet has been the means of identifying some species not hitherto recorded as English, though well known elsewhere, and at the same time of subjecting some others to a more searching examination than they had before undergone. The result has been the addition of the following genera to the English list, viz. Ceratotrochus, Pleurosmilia, Barysmilia, Rhizangia, and Leptophyllia.

Bibliography, etc.—This somewhat insignificant fossil approaches several of the small granulated or tuberculated species of Trochus (or Monodonta), which are distinguished by a completely conical outline, resulting from a close suture and perfect flatness of the whorls. Although without description, Phillips's figure is characteristic, and it is somewhat singular that this species was not recognized by D'Orbigny amongst the fossils of the French Jurassic. The typical form is confined, in Yorkshire, so far as I know, to the Scarborough Limestone (zone 3), where it is rare, and, for the most part, so imperfectly preserved, that accurate description is a matter of some difficulty.

The received theory of Slaty Cleavage has generally been held to afford a complete explanation of the observed phenomena. The proximate cause of the structure was shown by Dr. Sorby to be a superinduced arrangement of the flat and long-shaped fragments constituting the rock, in virtue of which they tend to lie in, or nearly in, the planes of cleavage; this arrangement being assisted, as Mr. D. Sharpe advocated, by a flattening of those particles themselves. These changes were ascribed to great lateral compression of the rock in the direction perpendicular to the cleavage-planes, together with some expansion along those planes in the line of their dip; and a great mass of evidence was brought forward to support this theory.

In the first place, let us obtain a clear idea of a Graptolite, and for this purpose we will consider two members of the family Dichograptidæ, namely, Didymograptus vacillans, Tullb. (Fig. 2, p. 452), and Dichograptus octobrachiatus, Hall (Fig. 1, p. 449).

In a short series of papers in this Magazine on How to work in the Archœan Rocks, I briefly set forth the principles of correlation which seemed to me available, and pointed out the precautions which should attend the application of each test. I discussed the evidence from (1) Organic remains; (2) Order of superposition; (3) Included fragments; and (4) Mineral composition. The lastnamed criterion has the widest application, and therefore it was necessary to define its scope with great care. I showed that its value largely depended upon accessory considerations. I insisted that rock-groups should be compared as a whole, that the degree of metamorphism was an important factor in the evidence, that a valuable auxiliary test was to be found in similarity of succession, that the proof of a Pre-Cambrian age enormously reduced the chances of error, and that, in some cases, the origin of the deposits was a useful aid in correlation. I recall attention to these points, because, at a recent debate in the Geological Society, some of my critics seemed to believe that I had been attempting to determine theage of formations by the comparison of a few hand-specimens. They omitted to take fully into account the subsidiary evidence which has been accumulated during the last decade. But even if we entirely ignore this mass of proof, it is surely of interest to point outlithological resemblances between rock-systems, even if we are not prepared to correlatethem. Twilight is better than absolute darkness. We may say that the Pebidian of Hicks is like the Lower Taconic of Emmons, without asserting the contemporaneity of the two groups; and then leave the lithological hint at the mercy of the evolutionary laws which will either destroy it or develop it into a theory.

My friend Prof. T. Rupert Jones, F.R.S., has lately received several Palæozoic fossils for examination from the rich collection of Mrs. Robert Gray, of Edinburgh, and has, with the owner's kind permission, placed two pieces of a very remarkabte fossil in my hands, for the purpose of examination and description.

Syenite.—Much of the eastern coast of Essex County, Massachusetts, extending from Salem to a point beyond West Manchester, has been found by the writer to be occupied by a typical syenite of a reddish and greyish colour, which in its macroscopic characters appears to be identical with that from Planen'schen Grund, Saxony. The syenite in places contains much biotite, and also, near West Manchester, quartz grains (segregations ?). This syenite is often cut by dykes of a fine-grained greyish syenite, which holds the same relation to the syenite proper as the micro-granite dykes do to the granite of the region, and hence, for convenience of description, the rock of the syenite dykes may be styled micro-syenite

IN his memoir on the Vertebrates of the Quercy Phosphorites, Dr. Filhol has described two species which he refers to the genus Cœnotherium, viz. C. commune and C. elongatum. Of the former only one ramus of the mandible is figured, and it is referred to a varietal form under the name of procommune: the latter, which is a small form, is known by the cranium and mandible. Both species have no diastema in the dental series. In addition to these, two small species are referred to the genus Plesiomeryx, under the names of P. cadurcensis and P. quinquedentatus, the latter being known only by the mandible; these forms are distinguished from the true Cænotherium by the presence of a diastema between the earlier premolars.

It was indicated even by Murchison that the Graptolites constitute admirable characteristic fossils of the Silurian formation. Subsequent investigation has established that the group Graptolithidæ is essentially confined to the oldest fossiliferous formation. A single genus, the genus Dictyograptus, Hopk. (Dictyonema, Hall), occupies a remarkably exceptional position as regards its distribution in time. Formerly, indeed, this genus was separated from the proper or true Graptolites (Rhabdophora, Allman), and referred with some other genera (Dendrograptus, Hall, Ptilograptus, Hopk., Callogroptus, Hall) to the Campanularidæ but recently W. C. Brögger has very clearly shown that the genus in question differs very little from the true Graptolites, inasmuch as the most important parts of the latter, such as the sicula, and the hydrothecæ, have been detected in it. By this the Graptolithic nature of the genus in question is rendered very probable. Members of the genus Dictyograptus, Hopk., appear among the very oldest of known Graptolites; the genus maintains itself throughout the whole of the Silurian formation, while by its side new genera make their appearance, culminate and disappear. Even after the other Graptolites had long since disappeared from the ancient sea-fauna, this genus still lived on, for we find it occurring in the Devonian.

The remarks by Professor Bonney on Dr. Sterry Hunt's recently published “Geological History of Serpentines,” which appeared in the September Number of the Geological Magazine, open up a very wide question—a question which broadly divides the nonchemical from the chemical geologists and petrologists. Dr. Sterry Hunt is well able to take care of himself in this discussion, and certainly I have no present desire to take part in it except so far as it relates to the Cornish areas, some of which are therein referred to. These I have especially studied, and with respect to them I feel bound to say that I find myself able entirely to agree with the conclusions of Dr. Sterry Hunt.

During the past four years I have made several traverses of the Central Alps from north to south, and venture to lay before you the general results as bearing in some respect on the geology of the Highlands.

Bibliography, etc.—Phillips's type was evidently a cast from the Kelloway Rock, of Hackness, near Scarborough. I have not been able to identify the original, which was supplied by Bean. The figure, however, plainly shows it to have been a cast of a good-sized discoidal shell, and there are specimens now in the Bean Collection at the British Museum not unlike it.

As introductory to the subject of this paper, some observations made in Ireland on foliation, or the structure induced by metamorphism, with other phenomena connected therewith, will be submitted.

From time to time, during earthquake-shocks, magnetic compass-needles within the disturbed areas have been seen suddenly deflected from their position of rest, returning to it shortly, after one or more oscillations. This movement admits of two very different interpretations. Either it may be attributed to an intimate connexion between earthquakes and terrestrial magnetism, or it may be regarded asmerely a consequence of the shock of the earthquake. The object of this note is to point out a possible mechanical cause, and to guard, therefore, against a too hasty assumption of a magnetic origin for these disturbances

Among the vast additions which, during the past five years, have been made to the palæontological collections in the British Museum (Natural History), none probably possess greater interest to the naturalist and comparative anatomist than the remains of the very remarkable group of aquatic phytophagous mammals known as the Sirenia, of which the “Manatee” and the “Dugong” are the living representatives.

Disregarding for convenience the internal volcanic forces of the earth, let us take for granted that we have an unlimited supply of fused silicates at a very high temperature; what will be the changes and effects produced in the escape of such matters upon the earth's surface ?.

That, at the great sources of volcanic material the igneous mass is in a completely fused state there can hardly exist any doubt. By this is meant that the magma is an intimate mixture of various chemical elements and compounds that have not yet assumed any other than the fluid state, or, in other words, that the molecules move freely amongst each other and have not arranged themselves in any definite crystalline form.