Within the last twenty years our knowledge of the structure and distribution of the armoured Placodermi (including Arthrodira, Ptyctodonta, Phyllolepida, Macropetalichthyida, Rhenanida, and Antiarcha) has increased tremendously. The writer is engaged on a morphogenetic analysis of the group, early publication of which is uncertain. A recent paper by Gross (1941) deals among other matters with the nature of the Antiarch pectoral limbs, and since my own conclusions partly support and partly oppose his very interesting hypothesis, it seems desirable to discuss separately the nature and possible evolution and morphogenesis of these unique vertebrate appendages. To do so it is necessary to review the paired limbs of other placoderms and of Acanthodii, with special reference to their functional significance.

Numerical taxonomic methods are applied to the Encrinurinae (Trilobita). Thirty-five cranidial and pygidial attributes are defined of which some (e.g. those relating to the glabellar tubercles) are specific to encrinurines and cybelines while others have application to non-encrinurids. Of nearly 200 named species of Encrinurinae only about one-third have been described in the literature in sufficient detail for their cranidial and pygidial attribute states be coded: a much smaller proportion of species is well enough known for librigenal, rostral, hypostomal and thoracic attributes to be coded. A comprehensive numerical taxonomy of the subfamily must therefore await detailed description of most of the known species. A list is given of encrinurine species in need of re-investigation. Meanwhile, 63 species can be coded for 34 attributes, and 75 species for 28 attributes. Principal components analysis is used to produce ordinations of these species. The minimal spanning tree superimposed on the ordination suggests possible evolutionary lineages. Ordination of the attributes is by non-linear mapping based on a distance matrix derived from the inter-attribute correlation matrix by the transformation (tanh−1 |r|)−1. The ordinations compare well with subjective assessments of relations and phylogenies.

The marine Mollusca obtained during the Scottish National Antarctic Expedition of s.s. Scotia are particularly interesting, not merely on account of certain benthal forms having been for the first time brought to light from unusual depths, but also as demonstrating an extended geographical range for certain meridional species already known; while the occurrence of sundry British and North European individuals in the Falkland Islands—perhaps brought there adventitiously—is, to some extent, a new feature in the fauna. Regarding the deep-sea species just alluded to, the dredging of a second example of the hitherto unique Guivillea alabastrina, Watson, from a station not far from the original Challenger locality, is very noteworthy; while we may at the same time signalise a Columbarium, Cuspidaria, Chrysodomus, and Dentalium, from 1775, 2645, 1775, and 1410 fathoms respectively.

The area examined in the course of this investigation comprises parts of Perthshire and Forfarshire fringing the Grampians and Strathmore from Stenton on the Tay, 2½ miles east of Dunkeld, to Auchnacree, a mile north-east of Noran Water, an easterly tributary of the South Esk. It is represented on a scale of 1 inch to a mile on Sheets 48, 56, and 57 of the Ordnance Survey of Scotland. The field mapping of over 130 square miles was carried out on a scale of 6 inches to a mile, and the results are embodied in the appended map on a scale of 1 inch to a mile.

Analysed compositions of coexisting phases from cordierite-amphibole-bearing rocks (cordierite-orthoamphibole-cummingtonite-garnet-staurolite-spinel-opaque ores) and mica schists (garnet-staurolite-biotite-muscovite-plagioclase-andalusite-quartz) have been used in conjunction with experimentally determined equilibria to estimate pressures and temperatures of metamorphism for the rocks of the Outokumpu district. The data do not determine a single point in P-T space, but bracket an area such that T ≈ 600 ± 50°C and P ≈ 3·5 ± 1 kb. These conditions represent the maximum temperature attained by the rocks, and the associated sulphide ore bodies, during the Svecokarelian orogeny and are consistent with a regional palaeogeotherm of c. 50°C/km.

Assessment of the composition of the coexisting phases in the cordierite-amphibole-bearing rocks, particularly the Fe-Mg-bearing phases, indicates that it is unlikely that either iron or magnesium was mobile during metamorphism and that the equilibrium assemblage represents essentially isochemical metamorphism of a rock composition that predates the metamorphism. A similar genesis is considered likely for the cordierite-anthophyllite rocks of Orijärvi in southern Finland which forms the basis of the classic statement of the magnesium-metasomatism hypothesis.

An account is given of the distribution and zonation of the moie important plants and animals found on rocky shores. Particular attention is directed to the variation which occurs in the dominant midlittoral communities of exposed shores, and to the wide range of low-level populations found in the sheltered sea-lochs.

Lower Carboniferous eurypterids are rare, and consequently the Scottish eurypterid fauna is of importance, in a world setting, because of the number of species of that age which it contains. Since the Scottish forms were originally described, great advances have been made in our knowledge of the Eurypterida which have made necessary the present critical re-examination of all available Scottish Carboniferous eurypterid specimens. Five species, belonging to four genera, are described and illustrated. Fresh evidence of the anatomy of Campylocephalus scouleri (Hibbert) is presented and the wider issues of eurypterid morphology raised by homology with this specialised species are discussed.

The main deformation of the Carboniferous sediments of north-east Northumberland took place in Armorican times. An analysis of minor structures shows that they occur in three distinct structural environments. These are, (i) as accommodation structures to large folds, (ii) as structures produced by transcurrent movement along lateral shearfaults, and (iii) as minor structures formed in direct response to the regional compression. The detailed interrelation-ships of these minor structures are described for selected areas.

In the neighbourhood of Berwick-on-Tweed a major east-facing monocline has been recognized. It appears that the large-scale folding of the Carboniferous strata was directly controlled by the configuration of the Lower Palæozoic and Lower Old Red Sandstone basement. Major folds have been generated by an east-west compression and are deflected around the Cheviot and Southern Upland masses. A regional fault pattern is interpreted as a conjugate system of strike-slip and oblique-slip shears. The nature and influence of structural control on the emplacement of the Whin Sill suggests that it was intruded during this same tectonic episode.

The object of this paper is to discuss the recently discovered encystment of Tardigrada, as far as our imperfect knowledge permits; to compare the process with that observed in certain low groups of the Acarina, in which the Tardigrada are generally considered to have their nearest relatives; then to inquire whether these new facts throw any light on certain puzzling facts in the physiology of the Tardigrada and Acarina, such as the retrogression which produces the simplex forms of Tardigrada, and which is said to accompany each moult of the Acarina; and lastly, if they contribute anything towards settling definitely the systematic position of the Tardigrada.

The Vila Pouca de Aguiar granite pluton, emplaced during the latest event of the Variscan orogeny of northern Portugal, is here subjected to a detailed study that combines magnetic fabric measurements and gravity modelling of its shape at depth. This laccolith, less than 1 km in thickness over ≈60% of its outcrop area, appears to be fed from its northern area, through narrow conduits, up to 5 km deep, belonging to a set of Y-shaped valleys that almost perfectly correspond to the local Régua–Verin fault-system identified in the geological maps. A normal petrographical zonation, already identified geologically, appears to be rather progressive, although a gradient in magnetic suceptibility magnitude in-between the two main magma types is evidenced. It is suggested that the first to be emplaced and the least evolved granite type (Vila Pouca de Aguiar Granite) upwelled from the local, NE-trending fault-zone, acting as a dyke, and formed a thin sill where NE-directed magma flow was dominant, at least close to the floor. The more evolved granite type (Pedras Salgadas Granite), located just above the main feeder zone, and deeply rooted at the intersection beween underlying faults, is at the centre of a remarkably regular concentric distribution of the foliation trajectories. They may reflect the late doming of the laccolith's northern part, coeval with a slight E-W extension of the inflating magma reservoir, as marked by the E-W-trending lineations. Along with ubiquitous magmatic to near-magmatic microstructures and particularly low anisotropy magnitudes, such patterns can be entirely explained by magma movement within its inflating reservoir. This composite laccolith, during emplacement of which no interference with the regional strain pattern can be recorded, is therefore considered as typical of post-tectonic emplacement.

The Rhizodontida (Pisces: Sarcopterygii) is a clade of predatory fishes from the Upper Devonian (Aztecia; ?Givetian of Antarctica) through to the Upper Carboniferous (Strepsodus; Moscovian of northern Europe and North America). They form the most basal plesion within the tetrapod stem-lineage. The mandibles were dominated by large symphysial tusks on the dentary. Not much else is known of the mandibles in primitive rhizodontids. However, later forms show several derived characters: the mandible is very deep dorsoventrally and narrow linguolabially; the coronoid fangs bear only a single fang and no other dentition; the Meckelian element was unossified, leaving the adductor fossa unfloored by bone; the prearticular produced a large dorsal process lingual to the adductor fossa, presumably for muscle attachment. These and other characters are discussed in the context of the evolution of the tetrapod stem-group.

The mandible appears to have been split into two functional units, one comprising the firmly sutured prearticular, coronoids and dentary, the other comprising the firmly sutured infradentaries. The connection between the two units was weak, suggesting a longitudinal intramandibular hinge. The possibility that this acted as a ‘torsion grip’ during feeding is discussed.

The morphologies of the hyobranchial apparatus in early tetrapods are reviewed, based primarily on first-hand examination and supplemented by published descriptions. The basic arrangement of the “aquatic” hyobranchium, with four pairs of branchial arches and internal gills, was conserved to a remarkable degree across the fish–to–tetrapod transition and was retained in further evolution in adults of several tetrapod lineages. Thus, a fish-like hyobranchium in basal tetrapods does not necessarily represent a larval or paedomorphic character, respectively, as was often suggested in analogy to extant salamanders. Rather, it represents the plesiomorphic state of the adult hyobranchium in tetrapods. The changes in the hyobranchium during the fish–to–tetrapod transition include the reduction of the number of skeletal elements and their morphological simplification. In all three presently discussed scenarios of lissamphibian origin, the temnospondyl, lepospondyl and diphyly hypotheses, the internal gills were reduced independently within temnospondyls and on the amniote stem below seymouriamorphs. Evidence of remodelling into a true “terrestrial” hyobranchium, with reduction of the posterior branchial arches and modification to support terrestrial tongue feeding, is scarce in early tetrapods. It evolved within temnospondyls in zatracheids, amphibamids and lissamphibians, as well as once or several times in early amniotes or in their immediate stem-forms.

The Briar Creek Bonebed (Artinskian, Nocona Formation) in Archer County is one of the richest sources of Dimetrodon bones in the Lower Permian of Texas, USA. Based on size, a small (D. natalis), an intermediate (D. booneorum), and a large species (D. limbatus) have been described from this locality. It has been proposed that these traditionally recognised species represent an ontogenetic series of only one species. However, the ontogenetic series hypothesis is inconsistent with the late ontogenetic state of the small bones, as suggested by their osteology and degree of ossification. Histological analysis of newly excavated material from the Briar Creek Bonebed has resolved some of the discretion between these two competing hypothesis, confirming the coexistence of a small (D. natalis) with at least one larger Dimetrodon species. An external fundamental system is present in the largest sampled long bones identified as D. natalis. The histology of D. natalis postcrania is described as incipient fibro lamellar bone. This tissue is a combination of parallel-fibred and woven-fibred bone that is highly vascularised by incipient primary osteons. The species status of D. booneorum and D. limbatus remain unresolved.

The marine invertebrate macro-fossils of the principal marine bands of Namurian age in Central Scotland are described. The species identified are listed and the vertical and lateral distributions of some species within the region are discussed together with notes on the palæogeography and palœoecology. Notes on the morphology of certain species are given and Campylites carbonarius (McCoy), Dyscritella leei sp. nov., Koninckopecten gen. nov. (type species Limatulina scotica Hind), Myalina mitchelli sp. nov., Palœoneilo mansoni sp. nov., Paleyoldia macgregori sp. nov. and Schizodus portlocki (Brown) are described.

In the SW part of the Southern Uplands of Scotland the relatively thin Moffat Shale Group (late Ordovician–early Silurian) is succeeded by a thick development of Silurian greywackes, of variable turbiditic facies. This includes late Llandovery (Telychian) quartzose greywackes with interbedded thin graptolitic shales of the turriculatus and crispus biozones, in the upper part of the Gala Group, a sequencewhich is laterally equivalent to the basal part of the Hawick Group. The age of the finer-grained calcareous Hawick Group, which here includes 1. the Ross Formation, ranges from late Llandovery (turriculatus Biozone) to early Wenlock (riccartonensis Biozone). The Riccarton Group, which contains thick units of thinly-bedded siltstones and mudstones, is of Wenlock age (riccartonensis to lundgreni biozones). Within this sequence, all the biozones of the standard graptolite zonal scheme have been recognised in the area, with the exception of the crenulata Biozone of the late Llandovery (Telychian Stage) and the murchisoni and ellesae biozones of the Wenlock (Sheinwoodian Stage). Details of the graptolite biostratigraphy areclosely comparable with those of the markedly thinner sequences of northern England. Acritarchs occur throughout the sequence but are most numerous and best preserved in the Gala Group. Poorly preserved chitinozoa and spores are also present, the former occurring sporadically throughout the succession but the latter become common only in the Riccarton Group.

A glance at a geological map of Middle Deeside shows that below Cambus O'May the valley is floored by a belt of metamorphic rocks flanked on both north and south by high hills of Younger Granite, of a date later than the regional metamorphism. The area of metamorphic rocks here considered extends from Cambus O'May down river to Banchory, but in the eastern half of this region the geological problems concern injection rather than tectonics. The cordon of Younger Granites enclosing the Deeside Schists is breached on the west near Cambus O'May by a mile-wide gap through which the metamorphic rocks escape to connect with those of the east side of Glen Muick. In this latter district the schists of as far south as the Aberdeenshire-Forfarshire watershed are considered in detail. Adjacent regions farther south and south-east are dealt with only in so far as they concern the correlation of the Deeside Schists.

As the Scotia was engaged in marine research throughout the whole of its long voyage out and home, it was only to be expected that Antarctic specimens would form but a small fraction of the result. In like manner, as several of the halting-places, such as the Cape of Good Hope and the Falkland Islands, had been visited by many keen naturalists on earlier occasions, it was quite likely that species of the group with which this report is concerned would have been in numerous instances already observed. Accordingly, out of some fifty species here discriminated, only six claim to be new, and not more than ten can be regarded as Antarctic or sub-Antarctic in their place of capture. In the vast extension, however, which marine zoology has for some time past been receiving, some retardation in the stream of discovery may not be unwelcome to the systematist. Familiar forms which would otherwise amply repay a thorough reinvestigation are apt to be thrust on one side, when striking novelties are for ever appealing to be introduced. This expedition, like others before it, affords fair evidence that the Macrura are both abundant and varied in great depths of the ocean. But only too often the frailty of their fabric leaves them in a tantalisingly mutilated condition when they reach the surface.

The Viséan sequence at East Kirkton was deposited in a shallow lake, set within a richly vegetated landscape formed of volcanic cones a few hundred metres high. There was little volcanic activity, however, while the lake existed, and the many tuff horizons within the sequence were washed in during weathering. The lake may have been generally cool, though of unusual water chemistry, as a result of which the spherulitic East Kirkton Limestone precipitated. At times, however, water temperatures may have risen sharply through localised hot-spring activity; both factors deterred ‘normal’ aquatic life.

The bulk of the preserved biota consists of plants (permineralisations and compressions) and dominantly land-living animals, including the oldest terrestrial tetrapods (amphibians and reptiliomorphs), large terrestrial-aquatic eurypterids, the first harvestman and rare millipedes. All these animals lived close to the lake, in a fire-prone forest dominated by gymnosperms and pteridosperms.

At a late stage in the history of the lake, deposition of spherulitic limestones was replaced by black shales, bearing a ‘standard’ Oil-Shale fish fauna, suggesting that the isolated lake had linked with a larger fish-bearing water body. This is coupled with a shift to a lycopod-dominated flora and may indicate a climatic change to wetter conditions. Finally the lake silted up with tuff, ending an existence of only a few tens of thousands of years.

Reservoir sedimentation provides a valuable source of data on sediment flux. This paper assesses the record of sedimentation in the Baldernock Mill dam, a small mill dam in western Scotland. That record is based on the volume of sediment in the dam, and the detailed analysis of a continuously sampled stratigraphic section through the impounded sediment, with a chronology for mill dam construction and subsequent breaching based on historical maps and the impounded sediment’s content of 137Cs and lead isotopes. The mill dam was constructed in c. 1820, was initially partially breached in the late nineteenth or early twentieth century and then fully breached by about the mid 1920s. The dam trapped relatively low volumes of sediment and the correspondingly low rate of sediment flux indicated by the volume of impounded sediment reflects the dam’s very low trap efficiency. The basal Unit 1 in the impounded sediments was deposited between dam construction and the initial breaching of the wall. The unit consists of repeated ‘triplets’ of a basal sand (flood deposit) grading upwards into a mud deposit (post-flood deposition), which is in turn overlain by an organic-rich layer of leaves and twigs (the subsequent autumn leaf fall). Unit 2 is similar to Unit 1 but lacks the organic layer, indicating the lack of ongoing standing water to trap the autumn leaf fall, and Unit 3 was deposited after full breaching of the wall. Mill dams in Scotland generally impound small steep bedrock channels – the latter reflecting a strong glacial legacy in Scotland – and are only small structures designed to ensure water for mills during dry periods in a climate of otherwise generally moderate to high and reliable rainfall. The small sizes of these dams and their low wall heights mean that they trap relatively low volumes of sediment that have minimal to minor downstream impacts if the dams fail.