A review is presented of the genera and species, both living and fossil, comprising the Superfamily Kraussinoidea and of their geographic and stratigraphic distributions. Two new fossil species are described, Kraussina chilensis and Megerlina miracula, from the Miocene of Chile and New Zealand respectively. The ontogenetic development of the brachidium in each of the four kraussinid genera is described and on the basis of recognised differences it is proposed that a new taxonomic subdivision is made that places Megerlia in a new subfamily Megerliinae, distinct from the other three genera in the existing subfamily Kraussininae Dall. The loop ontogeny of kraussinoids is compared with that of other terebratellidines and a phylogenetic linkage between kraussinoids and laqueoids is suggested.

Multidisciplinary three-dimensional modelling, involving geophysical, structural and geochemical data, has been used to study the relationships between magmatism, tectonics, fluid circulation and mineralisation in the northern Limousin, and to provide P-T-Z-t paths constrained by the available dating. The ore deposit occurrence displays little spatial relationship with granites emplaced in the 360-320 Ma period, probably because the low global permeability and tectonic regime did not allowed vertical fluid exchanges to be established. In contrast, the change in the tectonic regime induced by the delamination of the lower lithosphere (320-300 Ma), and characterised by the passage to general extension, has played a major metallogenic role. However, the ore deposit processes appear to be specific to each metal. Most of the W-Sn deposits appear to be synchronous with rare metal granites emplacement, at c. 310 Ma, that allowed the focus of fluids of different origins towards the apex of plutons. In contrast, for Au and U, the whole mineralisation process covers several tens of-millions of years. It is controlled by the regional tectonic evolution of the Limousin area during the same period, and especially by a rapid exhumation of the ductile crust which occurred in the 310-300 Ma period.

For a long time I was anxious to know the rate of expansion of the common building-stone of this neighbourhood, as it is not given in any of the tables of the expansions of substances, because I have sometimes thought that the vertical cracks frequently seen intersecting rubble walls might arise from the contraction caused by a diminution of temperature. During a long-continued and severe frost which occurred in 1826, I thought the rents in a considerable stretch of wall, which I passed at all seasons, appeared more open than usual. This, however, was merely conjectural, and I paid no more attention to the subject until 1830, when, as I mentioned in a notice on the commencement of my experiments read at the meeting of the British Association in September last, an interdict of the Dean of Guild Court of Edinburgh rendered the rate of expansion of stone a matter of more importance than merely a curious philosophical speculation.

Soil erosion can pose a serious problem to environmental quality and sustainable development. On the Tibetan Plateau, soil erosion is one of the main challenges to regional ecological security. Our analysis investigates soil erosion and evaluates its economic value in alpine steppe, alpine meadow, alpine desert steppe and forest ecosystems on the Tibetan Plateau. Analysis was carried out from 1984 to 2013. The results show that the annual average potential soil erosion, practical soil erosion and soil conservation calculated by the Revised University Soil Loss Equation model were 2.19×109ta–1, 2.16×109ta–1 and 2.72×107ta–1, respectively. The economic value of retaining soil nutrients, reducing the formation of wasteland and the economic benefit of reducing sediment deposition were 1.98×108RMBa–1, 2.55×1012RMBa–1 and 7.44×104RMBa–1, respectively. From comparing different ecosystems, we found that the forest ecosystem had the greatest soil retention and economic values. We also found that the potential and actual soil erosion values were extremely high on the Tibetan Plateau. The study highlights that state and local policymakers must give greater emphasis to ecological protection in the future.

The collection of echinoids, which is the subject of this report, was made by Mr R. A. Farquharson, M.A., M.Sc., F.G.S., Government Geologist, during his survey of British Somaliland in the year 1923–24. The collection was presented by the Colonial Office to the Geological Department of the British Museum, and the Keeper, Dr F. A. Bather, F.R.S., has been good enough to allow me to examine and describe these interesting specimens. I have been fortunate in having beside me for comparison the echinoids from Somaliland in the Hunterian Museum, which were collected by Mr B. K. N. Wyllie, B.Sc., F.G.S., and Dr W. E. Smellie, and through them presented by the Anglo-Persian Oil Company. I take this opportunity of expressing my thanks to Professor Gregory for his interest in the collection and for much kind help.

Zavitokichnus fusiformis n. igen. et n. isp. occurs in Lower Cretaceous (Valanginian to Hauterivian) limestones of the Fatric Superunit in the Western Carpathians. Typical cross sections of this more or less spiral trace fossil are sometimes U–O–C–S-shaped. In cross-section the trace fossil passes from a simple linear form, and spreads to a wider rolled-up or rolled-out form and then it returns to a linear trace. Spreite-like lamellae are distinguishable on several cross-section examples. The trace fossil was produced by a deposit feeder and it might be classified as a fodinichnion. Z. fusiformis co-occurs with trace fossil associations of Zoophycos, Chondrites, Planolites, Hormosiroidea and Palaeophycus in carbonate sediments of a deep-seated ramp along the margin of the Fatric intrashelf basin.

There is an important geometrical problem which proposes to find a curve having a given relation to a series of curves described according to a given law. This is the problem of Trajectories in its general form.

The series of curves is obtained from the general equation to a curve by the variation of its parameters. In the general case, this variation may change the form of the curve, but, in the case which we are about to consider, the curve is changed only in position.

This change of position takes place partly by rotation, and partly by transference through space. The rolling of one curve on another is an example of this compound motion.

Air photo interpretation and geochemistry have been used to supplement sparse field data in compiling a reconnaissance geological map of the area around the Lecht. Upper Appin and lower Argyll Group rocks are exposed, the best marker horizons being correlatives of the Appin and Jura Quartzites. Scatter plots, Q mode factor analysis and Pearson correlation coefficients of geochemical data were successfully used in the correlation of the pelite and limestone outcrops. The presence of major recumbent folds is inferred. The area is cut by numerous minor faults which are thought to be related to a major transcurrent fault, the probable north-eastern continuation of the Loch Tay fault, which was active in Lower Old Red Sandstone times.

The Lecht manganiferous ironstone is a seepage-bog ore type deposit derived by weathering of the local Dalradian sequence. Despite intensive leaching, this sequence still shows anomalously high levels of several elements, particularly Mn, Ba and Zn. In addition, stratiform sphalerite and manganiferous garnet are present in Blair Atholl Subgroup limestone and pelite horizons, respectively. Mineralogical and geochemical evidence suggests the presence of Zn–Pb–(Ag)–(?Au) exhalative mineralisation within the upper Appin Group Dalradian of the region, of which the Lecht represents the distal manganiferous expression.

The reconstructed palate of Whatcheeria deltae indicates a skull that was unusually narrow: at least 2.2 times longer than wide if the pterygoids are conservatively placed in the horizontal plane. This maximum width is narrower than any other early tetrapod reconstructed so far. Rotating the pterygoids to produce a vaulted palate would produce an even narrower skull. Primitive palatal features include very narrow interpterygoid vacuities and a vomer, palatine, and ectopterygoid with fang-sized replacement pairs. It is derived in that there is no anterior palatal fenestra and the premaxilla has a substantial palatal shelf – a combination of characters shared only with Proterogyrinus among early tetrapods. There is a possible septomaxilla in one specimen. Whatcheeria differs from and is more derived than Pederpes, its likely sister taxon, in that only the pterygoid is covered with denticles, the vomer, palatine, and ectopterygoid containing labyrinthine teeth only. Reconstructed dental occlusion indicates that the large choana apparently accommodated the large dentary fangs; this would be a unique feature among early tetrapods. The palatal ramus of the pterygoid is longer than the quadrate ramus, which does not have a descending flange. Like Meckel's cartilage in the lower jaw, the palatoquadrate is fully ossified in larger specimens, such that in a posterior view of the skull the pterygoid is mostly hidden from sight by the epipterygoid. The ossified neurocranium consists of the basiparasphenoid and basioccipital; no ossified sphenethmoid has been found. Remains of otic capsules are partial, crushed, and smeared, so no useful morphology is available. The stapes appears to be more columnar and less plate-like than in many other primitive, early tetrapods.

As Carnegie Research Scholar in Geology under Professor James Geikie, D.C.L., LL.D., F.R.S., at Edinburgh University, I have entered upon a systematic examination of fossil plants from Pettycur, Fife. Though many plants have been described from this locality, nothing systematic, as far as I know, has ever before been attempted. The main objects of this research are to endeavour to connect the various strobili obtained at the locality in question with the stems on which they were borne; to describe any new species met with, and to give some account of the mode of occurrence of the material in which the plants are enclosed. Some of these objects have already been attained, but others will require further study to decide.

Rowleya trifurcata gen. et sp. nov. is described from specimens discovered in coal-balls from the Union Mine of Burnley, Lancashire. It consists of slender cylindrical axes (0·3–1·4 mm diam.) branched at long intervals by anisotomous dichotomies. Often three closely consecutive dichotomies produce a lateral trifurcation in which one or both outer branches have been arrested in growth. These bear one or two pairs of vascularised tapering appendages interpreted as ‘leaves’. Main axes usually possess a tetrarch solid strand of primary xylem somewhat like certain branches of Stauropteris. Slightly smaller axes often have a triarch strand of primary xylem triangular in cross-section. Backwardly directed branches are occasionally borne above a trifurcation and opposite a pair of ‘leaves’.

Rowleya trifurcata is associated with Psalixochlaena cylindrica and Botryopteris hirsuta. Its closest affinities seem to be with Stauropteris and Psilotum.

In order to determine with exactitude the movements made by the wings in flight, and the part which the air plays in modifying them, I was induced several years ago to collect a large number of facts, and to undertake an extensive series of experiments with natural and artificial wings. My observations and experiments, I may remark, were not wholly confined to flight. On the contrary, I traced the analogy between flying, swimming, and walking; a circumstance which compelled me to pay particular attention to the size, shape, and movements, not only of wings, but also of the travelling surfaces of quadrupeds, amphibia, and fishes. By adopting this method, I obtained suggestions which have proved of the utmost importance to me in my attempts at elucidating the very intricate problem of flight.

Our climate future depends on the delicate, fine balance of earth processes first elaborated on by James Croll, born 200 years ago in 1821. A childhood victim of the Scottish clearances, Croll, after following various indifferent occupations, managed to remove to the then rapidly industrialising city of Glasgow and eventually to Scotland's capital, Edinburgh. He blossomed as a most original, outside-the-box, thinker of great intellectual strength and modesty. He carried out scores of studies across a broad range of research topics, many related to the physical causes of climate change. He is well known for his astronomical theory of the ice ages, but should be much better regarded for his incisive physical insights into the central importance of feedbacks in the Earth system. Although humble, Croll was an ardent controversialist who strongly, perhaps over-strongly, always defended his corner. As well as his many accomplishments as a man of science, Croll was committed to exploring philosophical questions of theism and determinism, topics which occupied his earliest and last publications. A ‘top ten’ selection out of the varied subject areas that Croll tackled are explored herein, along with a brisk survey of their legacy to contemporary modelling studies and to Earth's climate future: (1) causes of climate change (1864); (2) ice-cap melt and sea-level rise (1865); (3) predicting future climates using eccentricity (1866); (4) combining orbital precession, eccentricity and obliquity (1867); (5) geological time and the date of the glacial epochs (1868); (6) geological time and denudation rates (1868); (7) ocean currents and the hemispherical temperature difference (1869); (8) feedbacks – a remarkable circumstance which led to changes of climate (1875); (9) temperature of space and its bearing on terrestrial physics (1880); (10) the causes of mild polar climates (1884).

The influence of compression and dilatation in producing the doubly refracting structure in solids of all kinds, whether crystallised or uncrystallised, which do not possess it, and in modifying that structure in all crystals which do possess it, has been long known; but with this class of phenomena, those which I am about to describe have no connection whatever.

In the course of experiments on the double reflexion and polarisation of light which I discovered in the chrysammates of potash and magnesia, murexide, and other crystals, I was surprised to find that these substances could be spread out upon glass by hard pressure, like grease or soft wax, and that in the case of chrysammate of potash and other bodies, when the powder could scarcely be distinguished from snuff, I obtained a transparent film, exhibiting the phenomena of double reflexion and polarisation from its surface, as perfectly as if I had been using a large crystal.

The first instalment of this paper was devoted in great part to the general subject involved in its title, but many of the illustrations were derived from the special case of the flight of a golf-ball. Since it was read I have endeavoured, alike by observation and by experiment, to improve my numerical data for this interesting application, particularly as regards the important question of the coefficient of resistance of the air. As will be seen, I now find a value intermediate to those derived (by taking average estimates of the mass and diameter of a golf-ball) from the results of Robins and of Bashforth. This has been obtained indirectly by means of a considerable improvement in the apparatus by which I had attempted to measure the initial speed of a golf-ball. I have, still, little doubt that the speed may, occasionally, amount to the 300, or perhaps even the 350, foot-seconds which I assumed provisionally in my former paper:—but even the first of these is a somewhat extravagant estimate; and I am now of opinion that, even with very good driving, an initial speed of about 240 is not often an underestimate, at least in careful play. From this, and the fact that six seconds at least are required for a long carry (say 180 yards), I reckon the “terminal velocity” at about 108, giving v2/360 as the resistance-acceleration.

The district shown on the plate at the end of this paper belongs to an elevated portion of the much-dissected tableland known as the Highlands of Scotland. It stretches from the eastward-draining Dee to the southward-draining Shee and Isla. The watersheds between these three rivers determine the county boundaries of Aberdeen in the north, and Perth and Forfar in the south-west and south-east. They often rise well above 3000 feet, and where they meet in Glas Maol (I of Plate) they attain to 3502 feet. In the valley bottoms, Braemar on the Dee and the Spittal of Glen Shee both stand a little above the 1000-foot level. A connecting road, with a famous hairpin bend known as the Devil's Elbow (J), passes the Aberdeenshire frontier half a mile east of the Cairnwell at a height of 2199 feet. Its course furnishes an ideal geological traverse of the district considered as a whole.

Arthur's Seat is the remains of a dissected Lower Carboniferous volcano, from which were erupted a series of basaltic rocks representative of the province to which it belongs. The rocks occur as lavas, intrusions and tuffs, and include basalts of Dalmeny, Jedburgh, Dunsapie, Craiglockhart and Markle types, in addition to mugearite. For convenience the basalts of Dunsapie type have been subdivided into Normal and Feldspathic varieties.

The volcano has been remapped; some minor departures from the six-inch Geological Survey map are recorded and certain changes in the numbering and classification of the lavas have been made.

The petrographic characters of the various volcanic rocks are described in detail, with modal and chemical analyses. The composition of the parental magma of the volcano was probably very similar to that of Normal Dunsapie basalt. Markle and Craiglockhart types were produced as complementary differentiates of the parental liquid by a process of gravity differentiation, in which sinking of ferromagnesian crystals, particularly augites, played an important part. The basalts of Dalmeny and Jedburgh types, which in Arthur's Seat have strong chemical resemblances, probably represent only slightly differentiated parental magma. Concentrations of soda-rich volatiles produced intense albitisation in the Markle basalts and the mugearites. It is considered that the mugearites of Arthur's Seat crystallised initially as Jedburgh or Dalmeny types, and were altered to their present state during a deuteric phase.

An attempt has been made to reconstruct the eruptive history of the volcano. The magma source appears to have been replenished with parental magma at least twice during the period of activity. The first and last eruptions were of Dunsapie basalt; the albitised products appeared at a fairly late stage.

The development of D. (Didymograptus) murchisoni (Beck), the type species of the genus, is shown to be unequivocally of anus type, with thl1 dicalyal and a low metasicular origin of thl1. An evolutionary line from the early, Arenig, bifidus group is supported; and clear distinctions are drawn between the subgenera D. (Didymograptus), D. (Didymograptellus) and D. (Jenkinsograptus), the first of these being redefined. The range of variation of biocharacters of D. murchisoni is analysed using exquisitely preserved undeformed material from Saudi Arabia, and comparisons are made with the undeformed type material, and with undeformed (nodule) collections from Abereiddy Bay, Pembrokeshire. The astogenetically late developments of D. murchisoni are described.

81. A body which is either emitting heat, or altering its dimensions against resisting forces, is doing work upon matter external to it. The mechanical effect of this work, in one case, is the excitation of thermal motions, and in the other, the overcoming of resistances. The body must itself be altering in its circumstances, so as to contain a less store of work within it, by an amount precisely equal to the aggregate value of the mechanical effects produced: and conversely, the aggregate value of the mechanical effects produced, must depend solely on the initial and final states of the body, and is therefore the same, whatever be the intermediate states through which the body passes, provided the initial and final states be the same.