The ancient rocks of Leicestershire may be taken to comprise the pre-Cambrian volcanic and sedimentary rocks of Charnwood Forest, and the igneous rocks intrusive into them, viz. the dacite-porphyrites of Bardon Hill, Peldar, and High Sharpley, etc., the granophyric diorites and porphyrites within and south-west of the Forest and in South Leicestershire, and the Mountsorrel granite or granodiorite. There is reason to believe that all except the last are pre-Cambrian in age: for the last a post-Silurian age seems most probable. These ancient rocks are now exposed through the removal of the Keuper Marl, whichhad largely if not completely buried them. In glacial times, however, small areas have been reburied under glacial deposits.

In work on fossil brachiopods the present writer has found that descriptions and more particularly figures of the musculature of living froms are insufficiently explicit for parallels to be drawn with fossil specimens. These notes are the result of dissections of specimens of the living Terebratulinid Gryphus vitreus (Born) from the Marine Biological Station at Naples, and are intended primarily to elucidate the accompanying figures, which it is hoped might be of some value to palaeontologists.

THE Pre-Cambrian Association (Association Internationale pour l’Étude du Précambrien et des Vieilles Chaînes de Montagnes) was founded through the efforts of the late Professor J. J. Sederholm. It held its first excursion in Finland, 1931. Officers were elected, including Professor Sederholm as President and Drs. C. E. Wegmann and E. H. Kranck as Secretaries, but no definite policy was adopted. Since then about 130 geologists from many different parts of the world have expressed their interest in the enterprise. At the International Geological Congress in Washington, 1933, two meetings of the Association were held, and Professor E. B. Bailey was asked to organize an excursion to Scotland. This invitation he accepted for 1934, with Dr. W. J. McCallien as local secretary. In anticipation of the Scottish excursion Professor Sederholm and Dr. Kranck, in the absence of Dr. Wegmann, drafted provisional by-laws, and these were circulated.

IN the course of the Leicester meeting of the British Association in 1933, Section C visited the Nuneaton district and saw, amongst other exposures, sections showing the junction of the Cambrian and Pre-Cambrian. Two of these have never been previously described, and the most striking one (that in the north corner of Messrs. Boon’s quarry) was only first seen by the writers when on a preliminary tour of the excursion route. Both sections merit description, in view of the light which they throw upon the nature of the unconformable junction of the two systems, and upon the character of the Pre-Cambrian rocks and their relation to the rocks of Charnwood Forest.

In labelling specimens about 1866 from the Menevian of St. David’s, South Wales, Salter used this generic term for Stenotheca cornucopia, which is the genotype.

The seismicity of any region depends partly on the frequency, and partly on the intensity, of the earthquakes that occur within it. If earthquakes of all intensities are included in making such estimates, the weight to be given to the intensity must at present be to a great extent arbitrary. If, however, the determination is confined to earthquakes of the highest degrees of intensity, the results, though incomplete as representatives of the actual seismicities of the various regions considered, may yet give with some approach to accuracy their relative order of magnitude. The object of this brief paper is to provide such estimates for the various regions of the world and for the provinces of Italy that are shaken by destructive earthquakes.

Previous to 1858, the Northumberland and Durham Coalfield was considered to be destitute of any fauna other than the usual non-marine type. In 1858, J. W. Kirkby gave the first indication of marine fossils in this coalfield. He obtained specimens of Lingula credneri (Geinitz) from shales some 17 feet above the Five-Quarter seam during the sinking of a shaft at Ryhope, 3 miles south of Sunderland (9). Some of these specimens are figured by T. Davidson (2).

In 1916 the Whitwick, South Leicestershire, and Ellistown Collieries put down a boring near Ellistown Colliery in Leicestershire to prove the measures below the Deep or Roaster Coal. Early in the following year Professor W. W. Watts and I examined in detail the cores of this boring, and collected samples of the rocks and fossils from them. The rock-descriptions in the journal of the boring-foreman were checked and in many cases altered and enlarged by Professor Watts and myself after examining specimens in the laboratory, some of them in thin slices under the microscope. Mr. R. Bullen Newton, of the Natural History Museum, was good enough to name some of the fossils.

In a recent paper the author attempted to explain something of the mechanism of contamination in acid magmas, but nothing was said about the tendency, of contamination to produce normal rock types. It is to repair this deficiency that the present communication is presented.

The name crinanite was given in 1911 by Sir John Flett to a suite of N.W. analcite-dolerite dykes occurring in a fairly extensive district in Argyllshire of which Loch Crinan is the centre. A description of the type is accompanied by an analysis and a photomicrograph of a characteristic example from the island of Jura. Writing a few months later of similar dykes in Colonsay, the same author gives a concise definition of the type—“The crinanites, then, are dark coloured, fine-grained, basic rocks consisting mainly of olivine, augite, and plagioclase felspar, with a considerable amount of analoite and zeolites.” A detailed description follows, in which the very perfect ophitic structure of the rocks is emphasized, and another excellent photomicrograph is shown of an example from Colonsay. In his original description Sir John Flett states that the crinanites “present some analogies to the teschenites in mineral composition; from the latter they are distinguished by their finer grain, their perfect ophitic structure, the scarcity of hornblende and biotite, and their occurrence as thin vertical parallel dykes”.

A long the coast of South Wales is a series of plateaux, mostly at heights up to just over 400 feet above sea-level. They meet the coast in lines of cliffs, varied in character and often of great beauty. The most westerly area, in south and west Pembrokeshire, is the most perfectly developed, its level sky-line having been commented on by numerous writers (Dixon, 1921, p. 2; North, 1929, p. 23). The Gower peninsula, which is detached from the other coastal plateaux by Carmarthen and Swansea Bays, shows similar features, as does also the Vale of Glamorgan which stretches from the shores of Swansea Bay almost to Cardiff.

Some thirty years ago two species of Ophiuroidea and one Astereroid species were collected by one of us (Theodore Groom) from a small quarry near Rorrington in the Shelve District of Shropshire. There originally were several specimens but unfortunately the majority of these are now represented by plasticine casts only. The original material, was mislaid during a loan and was recovered in part only last year. The finder’s provisional description and figures, as well as his notes on the precise horizon and locality are still missing. It may be added that when, soon after the discovery of the specimens, their importance was realized an attempt was made to gain more material, the site was found to be built over. The specimens which are still to hand have been examined by Dr. Stubblefield, who says that there is no doubt that the matrix is that of the Spy Grit, a low Caradoc horizon, probably in the zone of Mesograptus multidens. It is from approximately this horizon that the majority of the British Ordovician starfish have been collected.

Mr. Hills’s paper suggests a number of questions, some of which can be fairly definitely answered, while others seem to me to be worth recording on the principle that the best way to get a question answered is to ask it. The separation of the granitic material into limited regions of the earth’s surface to form the continents could clearly not occur when the earth was fluid, and after the earth solidified any mechanical cause would meet formidable difficulties. Explanations seem to be restricted to (1) a failure or partial failure of magmatic differentiation in the oceanic regions, so that the granite has separated out since solidification in the continental regions, but remained dissolved in the oceanic ones, (2) some mechanical process arising during solidification. There are difficulties about both possibilities. Mr. Hills’s theory belongs to the second class, and I think needs serious consideration.