Much attention has been paid to composite dykes and sills during the present century, and accepted definitions of the term “composite” centre about that of Daly (1933), who has stated that composite dykes are formed by successive injection of chemically differing melts into the same fissure which widens to receive them.

THE country described in the following notes comprises the area lying between latitudes 10° N. and 11° 30′ N. and longitudes 8° 45′ E. and 10° E., and is situated in the northern portion of Bauchi province and the south-eastern portion of Kano province, Northern Nigeria.

A recent visit to Central Germany afforded the writer an opportunity of studying the conditions under which the Vogelsberg iron-ore and bauxite have been formed, and a brief account of what was observed may assist in broadening the basis upon which a sufficiently comprehensive view of the origin of those substances may ultimately stand. On this account my visit to the region was approved by the Department of Agriculture in Ireland, in connection with the work now in progress on the iron-ore and bauxites of co. Antrim. In my traverses I enjoyed the very agreeable companionship of Dr. Schottler, of the Grossherzoglich Hessischen Geologischen Landestaldt, and the advantage of his guidance. His elaborate description of the basalts in the vicinity of Giessen has since been issued, and is referred to in this paper. The admirable and exhaustive accounts of the bauxite by Professor Adolf Liebrich, and of the iron-ore by H. Münster, are also appealed to frequently. Among other important papers consulted regarding the chemical processes involved may be mentioned those of M. H. Coquand, Professor G. A. Cole, F.G.S., M.E.I.A., Max Bauer, Sir T. H. Holland, A.R.C.S., F.E.S., H. Warth, D.Sc., & F.J. Warth, B.Sc., Malcolm Maclaren, B.Sc, F.G.S., H. Brantwood Muff, B.A., and the summaries by F. Wigglesworth Clarke and Dr. C. Doelter.

Although the Coalbrook-dale Coal-field has received a large share of the attention of geologists, the progress of mining operations reveals new facts from time to time, enabling us to explain away some of the difficulties which have beset earlier writers.

The occurrence of a fish generically identical with Eurycormus of the Bavarian Lithographic stone, in the Upper Jurassic of England, has already been indicated by the discovery of a well-preserved head with some anterior vertebras in the Kimmeridge Clay of Ely. Only one specimen, however, has hitherto been recognized; and during a recent search for further evidence of the fish among British fossils the present writer has thus been gratified to find two more examples in the collection of the British Museum.

1. The Speeton Clay of Yorkshire contains abundant Foraminifera in the beds named by Mr. Lamplugh B (base), C10, and C2; but the specimens examined from the other subdivisions of F, E, D, and C either do not contain any Foraminifera or they are present in small numbers only.

2. Two new species, Cristellaria chapmani, Pulvinulina lamplughi, and a new variety, Lagena apiculata, var. danfordi, occur and are described. Forty-four species belonging to sixteen genera have been found.

3. The characteristic of the Foraminiferal fauna of the Speeton Clay is the great predominance of Pulvinulina caracolla (Roemer) over all other species.

4. Twenty-five per cent of the species of Foraminifera occur also in the Hils of North Germany, 35 per cent in the Red Chalk of Speeton, 40 per cent in the Bargate Beds of Surrey, and 58·5 per cent in the Gault of Folkestone.

5. Dimorphism is clearly shown by P. caracolla (Roemer). Previously it has been stated to occur among the Pulvinulinæ in P. partschiana, d'Orb., but no case has been described.

6. Notes are given on the microscopical characters of the sediments.

The genus Myalina was erected by Prof. De Koninck, in his Description des Animaux fossiles qui se trouvent dans le terrain Carbonifère de Belgique, for certain Modioliform shells, and M'Coy re-defined the genus in his British Palæozoic fossils and described two forms from the Permian of Durham.

The presence of Zieten's type-specimen of Ammonites calcar in the British Museum (Natural History) among some fossils which were bought of Dr. Bruckmann naturally suggested an examination of the other fossil Cephalopoda obtained from the same source, in the hope of finding other type-specimens. Thus far, the result of this examination has been the discovery of two more of Zieten's types; these are the type-specimens of (i) Ammonites polygonius and (ii) Ammonites discoides.

This species (under the generic name of Himantopterus)was first noticed by Mr J. W. Salter in the Quarterly Journal of the Geological Society for 1856 (vol. xii. p. 28, fig. 5); but only the penultimate segment and telson were then known.

In vol. xv. of the same Journal (1859), Mr, Salter described eight species of Eurypterus, from the Upper Ludlow Rocks and the Old Red Sandstone; but he did not refer to E. lanceolatus in that paper. Of these eight species of Eurypterus, E. pygmceus, from its smaller size, is the best preserved species. It occurs in the Downton Sandstone of Kington, in the Basement-beds of the Old Red Sandstone at the Ludlow Railway, and in the Upper Ludlow Rock of Ludford; and I have lately seen an entire specimen (in the cabinet of Mr. Jas. Powrie, F.G.S.), only one inch in length, from the Old Red Sandstone of Petterden in the Sidlaw Hills, Forfarshire.

For the purposes of a memoir, about to be published by H.M. Geological Survey of England, on the Geology of parts of Norfolk, I have been for some time past engaged in a critical examination and revision of such lists of the so-called “Pre-Glacial Forest Bed” Vertebrata, as have appeared from time to time in various publications. And it is intended to publish the results of this work in detail, when figures of the more important specimens will be given, together with particulars of the reasons for the alterations and additions which it is deemed necessary to make. It seemed desirable, however, as some time must elapse before the entire work can be accomplished, to publish, as occasion serves, short notes of some of the changes about to be made; and it is hoped that these notes will not be without interest to the readers of this Magazine.

Dolostones are widely developed in the middle Permian rocks of East Yunnan, China, mainly in the shoal-facies Maokou Formation. The previously reported dolostone formation mechanisms cannot explain the distribution and geochemical characteristics of these dolostones, in particular their strontium, magnesium and oxygen isotope signatures. To help predict the distribution of dolostone reservoirs and reduce the exploration risk and cost, this study proposes a new model of dolomitization: open thermal convection dolomitization. In this new dolomitization model, Mg2+ in dolomitizing fluids originates mostly from seawater, with a minor component coming from deep hydrothermal fluids. Elevated heat flux (in this case due to the nearby Emei mantle plume) causes spatial temperature variations in the fluid along the circulation flow pathways, resulting in fast and pervasive dolomitization of limestone. The proposed model not only explains the characteristics and distribution of dolostones in the study area but also serves as a reference for predicting the distribution of dolostones in other areas subjected to thermal convection.

Mr. Mansel-Pleydell's Memoir on the Geology of Dorset, contained in the last two Numbers of this Journal (pp. 402 and 438), refers to a theory of the formation of the Fleet proposed by Messrs. Bristow and Whitaker in 1869 (Geol. Mag. Vol. VI. p. 433).

Dr. Bonney having been so kind as to examine microscopically and describe a collection of crystalline rocks which I made in the vicinity of Assouan on the Nile, I have prepared the following notice of the geological conditions, to accompany his descriptions, referring, however, to the notes on the locality given in my paper in the Geological Magazine for Oct. 1884. Reference may also be made to the paper of Lieut. Newbold in the Journal of the Geological Society, vol. iv., and to that of Mr. Hawkshaw in the same journal, vol. xxiii. Lartet has given in his Geology of Palestine a summary of the observations of Russegger, Rivière and Figari Bey on the crystalline rocks of the Nile, and the allied rocks of the Sinaitic Peninsula have been described by him, by Bauerman and by Holland, and more recently by Hull. All these authors have given, more or less distinctly, a series of gneisses and micaceous and hornblendic schists associated with intrusive granites and diorites as the oldest rocks of these districts, and succeeding these in geological age, certain slates and associated rocks, with porphyry and basanite in beds and veins.