There have been in the past few years opportunities, which are not likely to recur, for collecting fresh and unweathered samples of the Upper and Lower members of the LondonTertiary series in the neighbourhood of Harrow. It therefore seemed to be worth while making a series of mechanical analyses of these samples for comparison with analyses which have been made of samples from the same formations in the other parts of the London basin.

The present paper summarizes some of the recent work on the stratigraphy of the Middle Carboniferous in the south-eastern and eastern parts of European USSR., work which throws new light on the position of the Moscovian stage in the Carboniferous succession. The Moscovian stage is at the present generally accepted as corresponding to the whole of the Middle Carboniferous (Danshin, Schwetzow, Khimenkow, and others), but the evidence of a break at the base of the Moscovian beds near Moscow justifies us in putting the question—is the Moscovian stage to be regarded as corresponding to the whole series of Middle Carboniferous deposits or was the deposition of the Moscovian series of beds preceded by erosion not only of part of the Lower Carboniferous, but also of part of the Middle Carboniferous? At the same time the new data concerning the character of the boundary of the Moscovian with the Upper Carboniferous tends to prove that at this boundary also there are signs of a hiatus.

This is the first of a series of contributions dealing with various aspects of the petrology of Barnavave Mountain which have not been touched upon by earlier investigators. The general relationships existing between the various rock types on Barnavave were first described by Traill in 1878, though some of the rock types had been previously dealt with by Haughton. This was followed by the now classical work of Sollas on some of the hybrids occurring on the western side of the mountain. These are at present being redescribed by Dr. G. D. Osborne in a paper which will appear shortly. More recently, the Carlingford area as a whole has been dealt with by Richey and Osborne has described the metamorphosed limestones of the region. Many of the rock types, however, have never been described in detail, if at all, and it is with these that the present contributions are concerned. The author wishes to express his thanks to Prof. W. J. Pugh, Prof. C. E. Tilley and Dr. G. D. Osborne for facilitating the work in various ways, to acknowledge a grant from the Worts fund and a Royal Society grant which defrayed the cost of two of the analyses. The field work was carried out in 1932 but unforeseen circumstances prevented the earlier working up and publication of the results.

Carriacou, the largest of the Grenadines lying between Grenada and St. Vincent, is the only one, so far as is known, of that group of islands which is not predominantly volcanic in origin. It may be described as the only limestone, or largely limestone, island in the whole inner arc of the Lesser Antilles which comprises Grenada, the Grenadines, St. Lucia, Martinique, Guadeloupe (west half), Montserrat, Nevis, St. Kitts, St. Eustatius, and Saba. Carriacou is 6¾ miles long and 2⅓ in greatest width and at High North Hill and Chapeau Carré rises to 980 and 960 feet. The remainder of the island is rugged and has several lesser peaks and a central ridge, running roughly north to south, 600–830 feet in height.

The granite mass of Dorback in the Braes of Abernethy, a few miles east of the village of Tomintoul, occupies an area of from 5 to 6 square miles, the plutonic rocks outcropping through the siliceous schists and granulites of the Central Highlands of Scotland. For a highland district the exposures are rather poor, since the igneous rocks only rarely appear from under a thick covering of peat and glacial drift, but towards the eastern margin of the mass the complex is well exposed in the valleys trenched by the Allt Iomadaidh and tributary streams. Here the interest of the plutonic rocks is twofold, for they form a complex of acid, intermediate, and basic types exhibiting considerable variation in petrography, and they include a series of xenoliths of quartzite, schist, and limestone which range from a few inches in diameter to a great mass of limestone 1½ miles in length. This xenolith has been mapped by the Geological Survey of Scotland, and it was the occurrence of a contact between limestone and plutonic rocks at this locality that led to the investigations of the authors.

One purpose of this paper is to place on record a new crinoid genus from Coplow Knoll, Clitheroe. The name Edapocrinus is proposed for its reception. Another is to note the discovery of two nearly complete crinoids at the same locality. This type of preservation is very rare at Coplow since the great majority of specimens found there consist of calices only and, except Actinocrinus and allied genera which have the lower brachials incorporated in the cup, it is only on a rare occasion that one finds a cup with any portion of the arms in position. In a paper to this Magazine, (1928, p. 246), I noted the discovery of the rare Flexible species, Euryocrinus rofei Bather and Gregory, which had part of the arms preserved, and remarked then on the scarcity of complete specimens of any species. Besides Coplow, this seems to apply to all the knolls in the Clitheroe region. Phillips, in his Geology of Yorkshire (1836), describes a considerable number of species from “Bolland”, most of which appear to have been collected by Gilbertson of Preston, and possibly some of the specimens were found at Coplow. All are cups only, with the exception of Poteriocrinus, now Taxocrinus nobilis, which is a complete crown. On different occasions during the last eight years, when I have made an annual visit to Coplow, I have found odd portions of arms, greatly displaced and not attached to any cup, usually in such a jumbled state that they were indeterminable.

In a recent account of the petrography of certain low-grade, dynamically metamorphosed quartzo-feldspathic sediments from the Forbes Range, Western Otago, New Zealand, one of the writers x has noted the presence of a yellowish-brown strongly pleochroic mineral, which was identified as a ferruginous member of the stilpnomelane group.

It has been shown that diorite tongues invading limestone have given rise to a series of contaminated rocks in which definite mineral assemblages may be recognized. These assemblages are sharply defined and occur in rude concentric arrangement about the tongues.

During the course of palaeontological work in the North Wales coalfield, shining discoidal bodies were noticed on the bedding planes of various shales. They were found to be identical with objects described as Guilielmites by Geinitz (4) in 1858. The literature concerning them is reviewed below, and a new theory of their origin is advanced.

THE terminology used to-day by British writers on Rugose corals is founded on the first competent terminology ever formulated, that of Henri Milne Edwards and Jules Haime, which was published in 1848, and added to during the following twelve years. These eminent French workers evolved a general terminology for corals as a whole and a special one for the sub-order Madreporaria Edwards and Haime. Their researches were more exact than those of their predecessors and called for more exact terms. Dana also realized the need for an exact terminology and introduced one some two months later (1848, p. 723); but it was less complete, less coherent, and less precise than that of Edwards and Haime, and has not been generally adopted by later writers.

Recently an account of the endogenous contact-zone of the non-magnesian limestones at Ben Bullen was published in this Magazine (Joplin, 1935 a), and it is now proposed to examine the effects of normal contact metamorphism in the aureole of the Ben Bullen plutonic complex.

The distribution of Gotlandian volcanic rocks covers a narrow belt running about N. 82° W.–S. 82° E., from South-west Ireland to Bohemia. The rocks comprise rhyolites, andesites, “keratophyres,” diabases, and basalts. Their age varies from early Valentian (Brabant) to Upper Salopian (Bohemia).

The Gotlandian vulcanicity, as a whole, was independent of the preceding Taconic orogeny, neither is its distribution parallel to the main Caledonian folding. The Irish-Belgian section of the belt corresponds closely to the northern boundary of the Westphalian Zone of the Variscan folding, a structural line of fundamental character. The Anglo-Irish occurrences are related to the intersection of this line with Caledonian and Malvernian structures ; those of Belgium and Bohemia are more truly geosynclinal in character.

1. The gneiss of the Sikait-Zabara district is in its mineral composition an aplitic granite, which has been subjected to intense pressure. It formed part of a magma of granitic composition which invaded a series of serpentines, themselves altered peridotites. The biotite-schist in many places immediately overlying the gneiss is the direct result of the assimilation of parts of the ultrabasic Tocks by the intrusive magma, the quartz, beryl, fluorite, tourmaline rock, and talc-schists associated with the biotite-schist bearing itness to the accompanying pneumatolytic action and silicification.

2. The schist from Kosha in the North Sudan most nearlyresembles the acid gneiss of Wadi Shalul in the Eastern Desert of Egypt. If the latter were originally a granite, as has been suggested from the analysis, then the Kosha schist would itself be an intensely crushed granite containing potash and soda in approximately equal amount.

3. The schist from opposite Khor Abdel Rahman in the North Sudan has been classified as fine-grained, epidote-albite-gneiss of uncertain origin.

4. The schist between Khors Abu Dom and Sila in the North Sudan has been compared with the rock from the Lewisian formations of Coll in Scotland. It may be termed a hornblende-granulite,representing an extreme case of metamorphism with crystallization under great stresses of an originally sedimentary rock.

5. The green schist from the Wadi Um Selman ravine, near the Dm Garaiat gold mine in South-East Egypt, is also regarded as an epidote-albite-gneiss, the bands being alternately quartzose and epidotic. The lime-containing minerals originally present have been altered to epidote and calcite.

6. The rock from Da'aba Island, in the Second Cataract, is an oligoclase-mica-diorite-porphyry, the felspar having been proved to be more acid than originally concluded. This name has therefore to be adopted in place of labradorite-dolerite, the term applied to it in pi. lxxx of Hume's Geology of Egypt, ii, p. i, 1934.

7. The rock of Arkasa Island, also from the Second Cataract, is, judging from the analysis, probably a more acid form of the oligoclase-mica-diorite-porphyrite series.

8. The specimens Nos. 8 to 11 represent a group of rocks in which magnesite plays an interesting part in the composition.

While No. 8 from Wadi Haimur is in the main a serpentine with but little magnesite, the remaining three rocks contain a notable percentage of this mineral. Pending further investigation, it is suggested that these changes may have taken place during periods when the ancient peridotites were submerged beneath the waters of the sea at various times in the geological history of Egypt.

Dr. Hume desires to thank Mr. 0. H. Little, Director of the Geological Survey of Egypt, very warmly for having left Mr. A. I. Awad free to carry out the petrographical studies for this paper whenever circumstances allowed of his doing so. This paper is published with the approval of H.E. the Surveyor-General of Egypt.

Among the fossils figured in the Silurian System (1839) is a cast of a dorsal valve of a brachiopod from Marloes Bay, named by J. de C. Sowerby Spirifer liratus. This form received more adequate description by Salter (1848) in the Memoirs of the Geological Survey, and in Murchison’s Siluria, and was later included under the generic name of Stricklandia, proposed by Billings (1859) for a certain section of the Pentameracea, and subsequently changed by him to Stricklandinia (1863). In subsequent descriptions, of which the most important are those of Davidson (1866), Angelin and Lindström (1880), and Schuchert and Cooper (1932), the form has always been referred to this genus.

In 1825 J. de C. Sowerby described and figured as Spirifer lineatus a brachiopod from the “ Wenlock Limestone ” of Dudley, choosing three syntypes; later he changed the specific name to radiatus. Of subsequent descriptions those of Hall (1852), Davidson (1866), Beecher and Clarke (1889), and Hall and Clarke (1894) are the most important. The present study is based on topotype material, while additional specimens for comparison have been collected by the writer from the Wenlock Shale of Malvern (Colwall Tunnel Tip Heap), from the Woolhope Limestone of Suckley, from the Wenlock Limestone of May Hill, and from the Tickwood beds and Wenlock Limestone on Wenlock Edge (railway cuttings near Presthope and Lilleshall Quarry). These, together with specimens from the Sedgwick Museum Collection, from the Birmingham University Collection, and from the British Museum (Natural History), have provided material adequately representative of variations in shape and size. Study has been made of external features, but more particularly of internal characters. The method of investigating the internal structures consists in grinding down the specimen either from the umbones, or from the lateral margin, and taking serial cellulose transfers at regular intervals, from which enlarged scale models may be constructed. Five specimens have been so treated, and as well as the construction of models, use has been made of perspective scale drawings to show the variations in internal structure. Growth lines are preserved on the transfers, but have in addition been examined in thin sections; specimens from Haverfordwest and Rubery preserved as casts have served to throw light on the muscle system, while finally the ventral valves of specimens preserved in shale, have been prepared to show the variations in internal structure.

In the early days of the study of glaciation the problem appeared to be a simple one: we are used to an ice-bound North Pole, and it was natural to assume that the boundary for some reason spread southwards to cover Scandinavia, Scotland, and even some of England. When it was further learnt that North America showed signs of extensive glaciation, this news fell naturally into place and scientists began to form hypotheses to account for a worldwide refrigeration. Quite soon, however, investigators in the countries concerned began to disagree as to the phases, and even the number, of glaciations: the centre of dispersal of the Scandinavian ice was found to be near the head of the Gulf of Bothnia; English geologists were inclined to favour only one glaciation, with certain retreats and advances; Boule would allow three glaciations, while Penck and Bruckner in their classical work on the Alps proved four in their region; Günz, Mindel, Riss, and Würm (with a short climatic improvement at the maximum); followed by the Bühl advance, Gschnitz Stadium and Daun readvance. But these Alpine phases cannot be followed into Italy. Gortani says (1): “Among us, too, Penck had disciples; and we, too, sought all means of adapting his system to the observed facts. But all attempts are vain because (a) nowhere are Günzian moraines to be found; (b) nowhere are to be found traces of more than one true interglacial with a warm climate and (c) the last two advances of the glaciers, where they have left separable traces, show themselves as two principal phases of one glaciation of medium intensity.”

It is unnecessary to emphasize the clarity with which overthrust structures are exhibited in the North-West Highlands of Scotland. Publications by B. N. Peach, J. Home, and their colleagues on the Geological Survey, following upon others of slightly earlier date by C. Callaway and C. Lapworth, have opened up this wonderland of geology to visitors from all parts of the world. Exposures of an overthrust mountain front extend for 120 miles from Durness to Skye. They exhibit many variations of style, of which no single locality is fully representative. At the same time, for a short excursion there is one specially favoured district. It lies in and about the Assynt culmination, where erosion has cut back the Moine nappe for several miles behind the normal line of outcrop, and has thus fashioned an extensive semi-window, through which an intriguing view can be obtained of underlying complexities (Fig. 1). The most useful publications on this district are the Geological Survey maps on the scales of a ¼ inch, 1 inch, and 6 inches to the mile, coupled with the great North-West Highland memoir and the beloved penny Guide to the Assynt Model. The most convenient hotel is Inchnadamph at the head of Loch Assynt.

The four genera discussed below are mentioned in almost every paper, memoir, and monograph dealing with the Lower Kimeridge Clay in this country and abroad. The first three were given currency in the literature of the Upper Jurassic when species belonging to them were chosen as index-fossils for the three lowest zones of the Kimeridge Clay by Salfeld (1913–14). Ataxioceras, though not comprising any zonal index fossils, is almost as important and has been repeatedly cited for 56 years from all parts of the world.

Pebble-Like aggregations of calcium carbonate have been described from certain lakes in the northern United States and southern Canada under such names as squaw biscuit, marlyte, and marl balls. The most northerly of the previous records of these structures in eastern Canada, known to the writer, cites them from Emerald Lake, a small Ontario lake in latitude 47 degrees. Structures of this type are known to be products of the growth activities of certain species of the blue-green algae. Those from Canandaigua Lake, New York, have the hardness of limestone and most geologists would be likely on casual examination to class them as flat water-worn pebbles of Palaeozoic limestone. Others, such as those found in Mink Lake, near Ottawa, Canada, are much softer and less compact than limestone.

Very little has been written about the Coelacanths from Madagascar, although those from similar formations in East Greenland and Spitsbergen are about the best known members of this group. Smith Woodward (1910) described and figured a single specimen as Coelacanthus madagascariensis, distinguished from other members of the genus by the ornament of closely set tubercles on the operculum. Further specimens were figured by Priem (1924) and attributed to C. madagascariensis, but no attempt at any detailed description was made. Dr. E. I. White, of the British Museum (Natural History), very kindly placed at my disposal a collection of these fish, which he had obtained himself. The material examined during this investigation consisted of these specimens, twenty-eight in number, and the original specimen described by Smith Woodward. The specimens were nearly all external moulds (although in some a certain amount of bone still remained) in ferruginous clay nodules. Very little preparation was necessary except washing. This treatment produced wonderful results in some cases and almost perfect impressions of the head were obtained. So perfect were these casts in many cases that the pores of the lateral line canal were left as small hummocks making parts of this system easy to identify.