Torridonian and Lewisian rocks lying in inverted order between the Kishorn thrust and the Moine thrust, and Moine rocks, lying above the Moine thrust, exhibit a remarkable parallelism of structure.

New evidence shows that three sets of minor structures have been developed in the formations during the Caledonian movements. At least two of these sets pre-date the Moine thrust movements. The mylonites, which are not restricted to the vicinity of the Moine thrust outcrop, belong to an earlier movement phase than these structures and are not directly related to the clean-cut thrust movements. They appear to represent narrow zones of shearing and sliding, mainly within the Lewisian gneisses that developed early in the Caledonian orogeny.

There is reason to suppose that the inversion of the rocks to the west of the Moine thrust occurred before the formation of the minor structures recognized in the paper.

The minor structures are described and their order of formation established. The plastic, para-crystalline style of the earlier deformation is contrasted with the post-crystalline brittle style of the later deformations.

It is well known that in many orders of typically winged insects species occur which in the adult stage are apterous or have the wings so reduced in size that flight is impossible. Sometimes the reduction of wings affects one sex only, as in the case of the females of certain moths, but in the majority of cases it is exhibited by both sexes. In many instances wing dimorphism occurs irrespective of sex, one form of the species having fully developed wings and the other greatly reduced wings. In some species the wings are polymorphic. The problem of the origin of reduced wings and of other functionless organs is one of great interest from the evolutionary point of view. Various theories have been advanced in explanation, but in the majority of cases the various aspects of the subject are too little known to warrant discussion. More experimental work is required to show how far environmental conditions on the one hand, and hereditary factors on the other, are responsible for this phenomenon. Those species which exhibit alary dimorphism afford material for the study of the inheritance of the two types of wings, but only in a few cases has this method of research been utilized.

Recent river erosion of three coalescing debris cones in Glen Feshie has exposed a complex sequence of debris flow units. Radiocarbon dating of organic matter from interbedded buried soils reveals that the soil at the base of the sequence was buried at c. 2000 yr BP, but that the bulk of the cones accumulated since the fifteenth century AD. The episodic nature of cone development is attributable to lateral migration of the River Feshie, with periods of cone accumulation when the river occupied the far side of its floodplain alternating with periods of erosion when the river impinged on the cones. There is no evidence to suggest that recent cone accumulation is related to anthropogenic vegetation disturbance, but phases of cone accumulation show a broad temporal correspondence with periods of Late Holocene climatic deterioration. The cones are essentially paraglacial in that their continuing accumulation depends on a supply of sediment derived from glacial and periglacial deposits upslope. The form of debris-flow units indicates that flows at this site were less viscous than most ‘hillslope’ flows, and cone volumes indicate an average annual accumulation of c. 50–60 m3 of sediment over the past c. 300years.

A growing body of evidence indicates that some, and perhaps most, plutons are highly composite. However, the geometrical forms of increments and the processes by which they are added are poorly known. Magmatic crack-seal probably is an important incremental assembly process, particularly in the upper crust where wall-rock fracture is important. Evidence for magmatic crack-seal is clearest where it is antitaxial, i.e., new fractures form at the contact between wall rock and a growing intrusion. Local deviation of antitaxial cracks into wall rocks isolates wall-rock bodies that therefore mark increment contacts. Wall rock isolated by this process remains in situ and thus is likely to preserve a ghost stratigraphy. Previously described plutons are identified, and interpreted to have grown by antitaxial magmatic crack-seal. In contrast, it remains unclear what observable geological record may remain in plutons formed by syntaxial crack-seal, in which new cracks form in the middle of the growing pluton. Several plutons are identified that preserve possible indirect evidence for growth by syntaxial crack seal, but conclusive identification of a direct record of the process remains elusive. However, plutons with sharp discordant contacts but few xenoliths may have been emplaced incrementally by syntaxial magmatic crack-seal.

Total contents of 29 trace and major elements and extractable contents of 20 elements were determined in the horizons of 4 profiles, 2 freely drained and 2 very poorly drained, of Scottish soils on drifts of basic igneous or granitic origin. The probable behaviour of other elements is suggested in the light of the results obtained. It is shown that in the course of pedological weathering, many elements are mobilised and become extractable by relatively weak reagents such as ammonium acetate (when readily exchangeable), dilute acetic acid (when less readily exchangeable or acid-soluble) or EDTA (when chelated or exchangeable). The forms in which different elements occur in the different horizons are assessed. In the surface horizons rich in organic matter many elements, such as Co, Ni, Fe, V, Cu, Cd, Sn and Pb, appear to occur mainly in chelated form; fewer, particularly Mn, are only in exchangeable form with plant uptake being largely responsible. Lower in the profiles the most common forms are acetic acid-soluble or, in gleyed horizons, exchangeable. In these horizons the degree of mobilisation is greater than in the corresponding freely drained horizons, the effect being most apparent for elements in readily weathered minerals.

The commonest arthropod trace fossils from Triassic aquatic red beds are the bilobate traces Isopodichnus and trackways known as ‘Merostomichnites’ triassicus. These trace fossils were probably produced by notostracan branchiopods, similar to Triops. Four arthropod ichnocoenoses from Lower Triassic fluvial sandstones have been analysed in terms of size frequency distribution, behavioural variation and relationship to sedimentary structures and depositional environment. One Isopodichnus ichnofauna associated with flute moulds (Dumfries-shire, Scotland) shows a normal age-structured population of arthropods responding with strong rheotaxis within shallow fluvial channels. The second Isopodichnus assemblage associated with ripple marks (Worcestershire, England) also shows strong rheotaxis but is bimodal in size and morphotype, possibly suggesting change in arthropod behaviour with age. Two ichnocoenoses of trackways with less pronounced rheotaxis associated with ripples (Cheshire, England) and flute moulds (Württemberg, Germany) were produced by larger arthropods than the resting traces. These arthropods probably possessed 6 to 9 pairs of walking limbs.

The conclusions derived from these notostracan trace fossils are compared with data on palaeoecology, population size-frequency, morphology and behaviour of Triops cancriformis derived from the analysis of three Triassic body fossil faunas and literature on living populations. Taxonomic consideration favours retention of the name Isopodichnus but the trackways should be included in Acripes Matthew. Brief review of late Palaeozoic Isopodichnus assemblages which appear to predate known notostracan fossils is inconclusive as regards both identifying producers or infallible means of separation from Cruziana assemblages.

Material of crossopterygian fishes from Foulden, Berwickshire, is important in including the first known entire specimen giving a clear picture of the body form of the Family Rhizodontidae (sensu Andrews 1973). This group is specialised in having numerous subsidiary lateral lines on the body, a ventrally expanded shoulder girdle, fins with peculiar stiffened structure, the pectorals forming greatly enlarged paddles and other fins being reduced in size. The Foulden remains fall into large and small size-ranges occurring largely at different levels in the sequence, but although these may represent growth in one taxon the available parts of the body are mostly complementary. Separate preliminary descriptions of the two size-ranges are therefore given, the small complete form being named ?Strepsodus anculonamensis sp. nov., and the large form remaining unnamed pending further study. An abridged historical account of previously named rhizodont genera (Rhizodus, Strepsodus, Sauripterus and Pycnoctenion) is given in order to explain why the new Foulden form(s) cannot at present be generically assigned more closely. A revised diagnosis of the Family Rhizodontidae leads to a discussion of the functional morphology and mode of life of fish of this type. Analogies with modern forms indicate that, like some sharks and crocodiles, they may have fed by tearing flesh off large prey, rotating or shaking against its inertia. Ways in which variously shaped rhizodont teeth (recurved, sigmoid etc.) may have functioned are suggested. Addenda deal with (1) the possible occurrence at Foulden of a large lungfish and (2) (after considering primitive and advanced rhizodont features) the renaming of Rhizodus ornatus Traquair 1878 from higher in the Scottish lower Carboniferous, as the type of a new genus, Screbinodus.

Westlothiana lizziae is known from the Brigantian of East Kirkton, Scotland. The skull resembles that of later amniotes in the large size of the parietal, the apparent loss of the intertemporal, and the absence of a squamosal notch, palatal fangs and labyrinthine infolding of the marginal teeth, but is primitive in the absence of a transverse flange of the pterygoid. The individual trunk vertebrae resemble those of amniotes; large intercentra are retained, but the neural arch is fused to the centrum. A surprising feature is the presence of 36 presacral vertebrae, as is the relative size of the very small but highly ossified limbs. The humerus is much shorter than the femur, but similar in configuration to that of early amniotes. There are three proximal tarsals as in primitive tetrapods, but an amniote phalangeal count. The presence of massive dorsal as well as ventral scales is a more primitive feature than that of most anthracosaurs.

Westlothiana is ‘reptiliomorph’, and is judged to be a stem-group amniote on features of the skull roof, the absence of an otic notch, the gastrocentrous vertebrae and the pedal phalangeal formula. It has not, however, reached the amniote condition in the structure of the tarsus, and the palate is more primitive than that of both early amniotes and the ‘diadectomorphs’.

An association of 100 teeth and 15 vertebrae from a large, lamniform shark, is described from the uppermost part of the Gearle Siltstone in the Giralia Anticline, Southern Carnarvon Basin, Western Australia. The material represents a new genus and species: Cardabiodon ricki. The taxon is referred to the new family Cardabiodontidae on the basis of its dental formula and uniquely oversized lower lateroposterior teeth. Other characteristic features include a strong dignathic heterodonty and the presence of four anterior and approximately 14 lateroposterior toothfiles in both the upper and lower jaw. The size of the recovered vertebral centra indicates that the shark measured at least 5 m in total length. The species had a wide but possibly patchy distribution with additional occurrences in England and Kazakstan, where it is present in strata of Cenomanian age. Cardabiodon shares several key dental characters with Parotodus, known from Oligocene–Pliocene deposits. The latter taxon was previously grouped with the ‘mega-toothed’ sharks of the genera Otodus and Carcharocles, but is here reassigned to the Cardabiodontidae.

The nominal species Cretalamna woodwardi from the middle or late Cenomanian of southern England, is designated as the type species of the new genus Dwardius. The coeval nominal species Pseudoisurus tomosus from the Saratov region in Russia, is based on material that almost certainly includes C. ricki and/or D. woodwardi. Designation of a lectotype for P. tomosus and its proper documentation would probably allow either C. ricki or D. woodwardi to be synonomised with the older name P. tomosus. There is, however, a strong possibility that the syntypes of P. tomosus are lost. Until they are found, redescribed and compared carefully with the type material of C. ricki and D. woodwardi, P. tomosus is a name of doubtful application and therefore referred to as a women dubium

The following paper contains, in a compact form, the substance of several somewhat bulky communications laid before the Society during the present session. The gist of each of these separate papers will be easily seen from the abstracts given in the Proceedings. These contain, in fact, many things which I have not reproduced in this digest. Nothing of any importance has been added since the papers were read, but the contents have been very much simplified by the adoption of a different order of arrangement; and long passages of the earlier papers have been displaced in favour of short general statements from the later ones. With the exception of the portion which deals with the main question raised, this paper is fragmentary in the extreme. Want of leisure or press of other work may justly be pleaded as one cause; but there is more than that. The subject is a very much more difficult and intricate one than at first sight one is inclined to think, and I feel that I have not succeeded in catching the key-note. When that is found, the various results here given will no doubt appear in their real connection with one another, perhaps even as immediate consequences of a thoroughly adequate conception of the question.

Little is known regarding the internal anatomy of thelodonts, with most of the available information coming from a single specimen, the holotype of Turinia pagei (Powrie). Previous descriptions have led to many partial, or conflicting interpretations. Herein, we describe fully the anatomy of T. pagei based on the holotype and additional material. T. pagei possessed a branchial system composed of eight pairs of gills, a buccal/nasohypophyseal region lined with minute denticles, comparable to buccopharyngeal denticles of sharks, and possessed a stomach which is preserved by sediment infill in the holotype specimen. Contrast between the petrological character of the gut infill and the sediment in which the animal is preserved suggests that the gut was infilled in vivo and that T. pagei was probably a deposit feeder. Phylogenetic analysis resolves T. pagei and the Galeaspida as sister-taxa, comprising a sister-group to the Osteostraci plus jawed vertebrates. In contrast to the view that has prevailed hitherto, thelodonts with a dorsoventrally compressed cross-sectional profile comprise a monophyletic group, of which T. pagei is the least derived member. The furcacaudiforms are resolved as an unnatural group, one taxon being the sister taxon to the ‘conventional’ thelodont clade, and the other, the sister taxon to this clade plus galeaspids, osteostracans and jawed vertebrates. The analysis agrees with the earlier view that thelodonts lack distinct synapomorphies, but we argue that distinct synapomorphies are not a requisite of monophyly.

The theory of the Quaternary climate will be incomplete unless it is embedded in a more general theory for the fuller Cenozoic that can accommodate the onset of the ice-age fluctuations. Here we construct a simple mathematical model for the late Cenozoic climatic changes based on the hypothesis that forced and free variations of the concentration of atmospheric greenhouse gases (notably CO2) coupled with changes in the global ocean state and ice mass, under the additional influence or earth-orbital forcing, are primary determinants of the climatic state over this long period. Our goal is to illustrate how a single model governing both very long-term variations and higher frequency oscillatory variations in the Pleistocene can be formulated with relatively few adjustable parameters. Although the details of this model are speculative, and other factors neglected here are undoubtedly of importance, it is hoped that the formalism described can provide a basis for developing a comprehensive theory and systematically extending and improving it. According to our model the major near-100 ka period ice-age oscillations of the Pleistocene were caused by the downdraw of atmospheric CO2 (possibly a result of weathering of rapidly uplifted topography) to low enough levels for the ‘slow climatic system’, including glacial ice and the deep ocean state, to become unstable.

Skeletal remains of Tristychius arcuatus commonly occur in ironstone nodules from the Scottish Upper and Lower Oil Shale Groups. This material is clearly distinguishable from the small shark from Glencartholm described by Traquair, Woodward and Moy-Thomas under this name. Study of the latter shows that its finspines are distinctly different from the holotype of T. arcuatus and, therefore, it has been renamed.

Tristychius arcuatus sensu stricto is a medium-sized hybodont shark with a short gape, a functionally heterocercal tail and narrow-based, tribasal pectoral fins. Its most unusual feature is a well developed opercular gill cover composed of long hyoid rays. Evidence suggests that this character was present in several Palaeozoic sharks, although it is absent in all Recent elasmobranchs. It is not clear whether it was primitively present in chondrichthyans or evolved separately in several lineages.

Hybodonts and ctenacanths are recognised as separate, specialised shark radiations, neither of which can be directly ancestral to Recent sharks. Of the two, hybodonts appear to be more closely related to Recent forms, although the presence of typical hybodont finspines in Tristychius arcuatus indicates that they had diverged from ancestral euselachians before the beginning of the Carboniferous.

The work, of which the results are described in the following pages, was carried out in the Department of Zoology of the University of Sheffield and at the Laboratory of the Marine Biological Association, Plymouth. I wish to thank the British Association and the University of Sheffield for the use of tables at the Plymouth Laboratory, and I would also express my gratitude to Dr C. M. Yonge for much assistance, particularly for the loan of numerous papers.

During five seasons the writer has been investigating the fishes of the Middle Devonian flagstones in the quarry at Achanarras in Caithness. This celebrated quarry, the home of Palœospondylus, has been long known and has been previously worked by Traquair (1890, 1894), who has described its fauna. There appeared, however, still to be room for a more detailed and intensive examination of the fauna such as could only be produced by a more extended period of work than had so far been given to it. By permission of Colonel Murray-Thriepland, the owner of the estate on which the quarry is situated, I have been able to spend the seasons of 1931–1935 in making a collection, of which a part is now to be described. To the Colonel and to his son Mr Peter Murray-Thriepland I have been indebted throughout for their unfailing interest and assistance. The main part of this account was written in 1934, but was not published owing to the discontinuance of a foreign journal for which it had been accepted. The season of 1935 produced some further material, which has now been incorporated. Meanwhile the writer has had the opportunity of discussing questions relating to the genus Dipterus with Dr Stanley Westoll, who has in preparation a work on the Devonian fishes in general, and is indebted to him for information on several points. Dr Westoll's view that the scales show an alternate deposition and resorbtion of the outer layer together with its bearing on questions of species is here fully adopted (Westoll, 1935).

In the following remarks I intend to confine myself to the consideration of those compounds which have not only the same composition per cent., and the same molecular weight, but also the same constitutional formula. Such compounds may be termed absolutely isomeric. As the constitutional formula of few substances is fully known, this class is of course a small one, or rather there are few substances of which we can certainly say that they belong to this class.

A few words of explanation are necessary at the outset in connection with the terms used in association with the animals upon which these investigations were made.

Dealers in ferrets supply two types of animals—one with yellowish-white fur and pink eyes, which they call “ferrets,” and a second type in which the yellowish fur is intermingled with a varying admixture of brownish or brown-black hairs; the second type they call “polecats.” The polecats of the ferret-dealers are not, however, true polecats, for Miss Frances Pitt, who has bred ferrets and polecats and ferret-polecat hybrids in a scientific manner, and to whom I am indebted for the greater and best part of my information on this subject, points out that the so-called polecat of the dealers is never so dark and handsome in colour as the true polecat. Moreover, as Miss Pitt states, in the true polecat the light marks in front of the ears do not usually join across the forehead, whereas in the polecat of the dealers they form a band across the face; further, when viewed from in front and above, the head of the true polecat has the form of a fairly equilateral triangle, whilst in ferrets and the so-called polecats of the dealers the head, on the whole, has the form of an isosceles triangle.

Outstanding structural features related to habits of life in the chydorid cladoceran Eurycercus lamellatus are described. Crawling is as important as swimming in this deposit-feeding species. The nature of the food, its collection and subsequent manipulation, are described. Both cephalic and trunk appendages are involved in this process. Their structure and mode of action are described and illustrated in detail. Many hitherto unknown structural features are described and the functional significance of these and other morphological peculiarities is explained.

I-type granites can be assigned to low- and high-temperature groups. The distinction between those groups is formally based on the presence or absence of inherited zircon in relatively mafic rocks of a suite containing less than about 68% SiO2, and shown in many cases by distinctive patterns of compositional variation. Granites of the low-temperature group formed at relatively low magmatic temperatures by the partial melting dominantly of the haplogranite components Qz, Ab and Or in H2O-bearing crustal source rocks. More mafic granites of this type have that character because they contain restite minerals, often including inherited zircon, which were entrained in a more felsic melt. In common with other elements, Zr contents correlate linearly with SiO2, except sometimes in very felsic rocks, and Zr generally decreases as the rocks become more felsic. All S-type granites are apparently low-temperature in origin. After most or all of the restite has been removed from the magma, these granites may evolve further by fractional crystallisation. High-temperature granites formed from a magma that was completely or largely molten, in which zircon crystals were not initially present because the melt was not saturated in that mineral. High-temperature suites commonly evolved compositionally through fractional crystallisation and they may extend to much more mafic compositions through the production of cumulate rocks. However, it is probable that, in some cases, the compositional differences within high-temperature suites arose from varying degrees of partial melting of similar source rocks. Volcanic equivalents of both groups exist and show analogous differences. There are petrographic differences between the two groups and significant mineralisation is much more likely to be associated with the high-temperature granites. The different features of the two groups relate to distinctive source rock compositions. Low-temperature granites were derived from source rocks in which the haplogranite components were present throughout partial melting, whereas the source materials of the high-temperature granites were deficient in one of those components, which therefore, became depleted during the melting, causing the temperatures of melting to rise.

Two new species of petrified seeds Eosperma edromense, and Anasperma burnense gen. et sp. nov. are described from the Cementstone Group of Berwickshire. Anasperma shows that the anatropous condition existed among Palæozoic ovules; it has a single integument with two lateral apical lobes.

Rachides of Stauropteris berwickensis sp. nov. and associated megasporangia are also described.

An account is given of the theory of the telomic origin of the first ovular integument. The second (outer) integument in Angiosperm ovules may therefore have evolved after the establishment of anatropy, either from the first integument or as an overgrowth of the chalaza. Evidence is cited to support the theory that Angiosperm carpels have evolved from dorsiventral bivalved cupules.