Outputs of suspended sediment and bedload from the 7·7 km2 moorland Monachyle basin and the 6·8 km2, 40%-forested Kirkton basin near Balquhidder, and inputs from tributary streams and mainstream bank erosion, are compared. Sediment yield is about three times higher in the forested basin and varies more sensitively with streamflow, suggesting greater availability of erodible sediment. The output is predominantly of suspended sediment and is derived mainly from tributary streams. Initial observations following partial moorland ploughing and forest clearfelling in 1986 indicate that erosion of timber loading areas and logging roads is the main sediment source.

The acquisition of a preserved fœtal specimen of the African Elephant has enabled the writer to prepare a series of papers on the anatomy of this interesting Mammal. The present paper forms Part III of the series. Part I (1926) dealt with the anatomy of the head, Part II (1928) with the body muscles. The contents of the thorax and abdomen have now been investigated, and Part III is concerned with a description of them and of the remaining parts of the skeleton. This part is the last of the series.

The Palæozoic ovule, to which the generic name “Sphærostoma” is now given, was originally described by Williamson in 1877 under the names Conostoma ovale and Conostoma intermedium. He referred sections of different individuals to different species owing to the imperfect condition of the material then available, but expressed the view that Conostoma intermedium “may possibly be a state of Conostoma ovale.” The new material has rendered this interpretation a certainty. With respect to the reference of this ovule to the genus Conostoma, Williamson again expresses some hesitation, merely stating that “it appears to be of the same generic type.” The genus Conostoma was established for an Upper Carboniferous ovule which Williamson designated Conostoma oblongum.

The Berwickshire Cementstone Group was deposited on a coastal plain crossed by meandering rivers flowing S into a marine gulf, the Northumberland basin. Sedimentation was mainly by overbank flooding onto an alluvial plain which largely dried out between floods. The resulting sediments include poorly-stratified mudstones and siltstones and crevasse splay sheet sandstones. The depositional environment of the cementstones is not clear. Lacustrine and tidal flat origins are considered. Semi-permanent floodplain lakes were very rare, but in one the uniquely fossiliferous Foulden Fish Bed was deposited. This lake was shallow and filled by repeated influxes of sediment carried from rivers by sheetfloods. On entering the lake, these sheetfloods may have become density underflows from which thin, graded siltstones or sandstones were deposited. These floods carried plant debris into the lake and rapidly buried the remains of the lake fauna. The salinity of the lake cannot be determined, but the input of both fresh and saline waters can be envisaged. There is no evidence that the lake was permanently eutrophic. The mortality of the animals may have been due to changes in water chemistry produced by hot dry spells of weather followed by storms and floods.

An attempt has been made to determine the identity of two desmids commonly recorded from the plankton of British lakes, Staurastrum paradoxum and S. gracile. The original descriptions of these species were clearly inadequate and many subsequent investigators have given their own interpretation as to their identity, so that from the British plankton alone at least six well-defined taxa have been referred to as S. paradoxum and four as S. gracile. Owing to this confusion, and in the absence of type material, it is suggested that the species S. paradoxum cannot be maintained. On the other hand, type material of S. gracile exists in the British Museum and has been re-examined. The principal characters of this species are described and figured and a list of synonyms given. In addition, those Staurastrum species and varieties frequently misnamed paradoxum or gracile, have been described in detail.

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.

Under the name Conversion of Relief, an expression first used by Mr Wheatstone, I include all those optical illusions which take place in the vision of cameos and intaglios, of elevations and depressions, whether they are produced with opaque or transparent bodies,—on surfaces with or without shadows,—in reflected or transmitted light,—while using one or both eyes,—or by erect or inverted vision. In these various forms of the phenomenon, the illusion is modified by certain secondary causes, which were regarded both by Mr Wheatstone and myself as primary causes; so that we were led away, each in a different direction, from the right path of inquiry.

I am greatly indebted to Dr W. S. Bruce, the able leader of the Scottish National Antarctic Expedition, for the opportunity to describe the Scotia collections as regards the Pycnogonida and the Isopoda. We are now concerned with the Pycnogonida, and I regret that there has been so much delay before the production of the report. The collection is a large one, and extremely interesting—totally different from that made by the Discovery in the same region, but on the opposite side of the world. If smaller in the number of species brought home, in number of individuals it far exceeds that collection. Its principal interest lies in problems of distribution.

During the past few years probably no group of fossil plants has received more attention from palæobotanists than that of the Pteridospermeæ. Many fern-like impressions, derived from Carboniferous rocks, have proved to be members of this division of the vegetable kingdom; while many more may ultimately be removed from the Filicales and included in the Pteridospermeæ. Specimens, however, in which the internal structure is preserved, may, as a rule, be correctly referred to their respective class, but among those included in the latter group there is considerable diversity of organisation, and recently described genera have tended to increase the diversity of type rather than to indicate relationships among the forms already known.

Abundant microvertebrate remains from the Siberian Platform are described as early acanthodians. All are preserved with both excellent morphology and histology. They are assigned to a new order, Tchunacanthida, with two new families, Lenacanthidae and Tchunacanthidae. These comprise two new genera, Lenacanthus and Tchunacanthus with type species L. priscus sp. nov. and T. obruchevisp.nov. The evidence from the morphology and histology is that they are the most ancient acanthodian scales so far found. The total collection of vertebrate material from the Irkutsk amphitheatre is described, together with their geological distribution, geographical range and systematic palaeontology. Head scales, tesserae of three morphotypes, transitional scales and body scales have been found. All comprise morphological sets as determined by comparison of morphology using SEM and of histology using Nomarsky interference optics. Observations of growth were possible from details of concentric lines on the crown and also from incremental layers seen in both horizontal and vertical sections. Starting from the primordial scale, consecutive layers are added, coronally, laterally, and deep in the corium onto the base; these occurred simultaneously in both crown and base. A type of areal-superpositional growth occurred in some body scales but in other scales there was little superpositional growth. It is concluded that Tchunacanthus possessed very solid body armour with tightly joined scales covering a large area of the body, and scale bases deeply set in the corium. Both tissues of the scales, dentine and bone, feature enclosed cells. This character is regarded as primitive within acanthodians, as in derived forms both tissues are acellular. Acanthodian scales are one of many examples of transformation from cellular to acellular tissue in evolution.

The Stac Fada Member, which forms part of the Stoer Group, contains the only definitive evidence of volcanic activity within the thick Torridonian succession. At the type area in the Bay of Stoer, four volcanic-rich sandy mudstone units are recognised in the Stac Fada. An irregular erosional contact at the base of the main Stac Fada unit truncates two thinner layers of similar volcanic-rich material that were formerly interpreted as intrusions. Directional sedimentary structures associated with the Stac Fada mass flows, and the distribution and thickness of an accretionary or armoured lapilli tuff, support the existence of at least two volcanic sources. Geochemical evidence suggests that the thick Stac Fada unit at the Bay of Stoer and comparable units to the SW were derived from the same volcanic centre. The chemical composititon of volcanic fragments in the main Stac Fada unit indicates that their potassic nature is not a primary feature but is due to alteration and subsequent metasomatism.

Bellerophontidæ occur in considerable numbers at certain horizons in the Scottish Carboniferous rocks. Many forms are represented, but few have been described or figured (see Historical Account, Section III). In undertaking the study of these fossils the writer's object was limited, primarily, to figuring and describing the Scottish forms and ascertaining their value as stratigraphical indices in the Scottish Carboniferous rocks. Many forms from the shaly facies have been recorded in Scottish stratigraphical literature under the names of English and Belgian species of limestone facies. Investigation proved that most of these records were invalid, the determinations being erroneous, and that revision of all the Anglo-Belgian Bellerophontidæ was necessary in order to define the Scottish forms. The present memoir embodies the results of the wider investigation.

The problem of the origin of dinosaurs has historically had three dimensions. The first is the question of whether Dinosauria is monophyletic, and of its relationships to other archosaurs. This question was plagued from the beginning by a lack of relevant fossils, an historical burden of confusing taxonomic terms and a rudimentary approach to devising phylogenies. The second dimension concerns the functional and ecological adaptations that differentiated dinosaurs from other archosaurs, a question also marred by lack of phylogenetic clarity and testable biomechanical hypotheses. The third dimension comprises the stratigraphic timing of the origin of dinosaurian groups with respect to each other and to related groups, the question of its synchronicity among various geographic regions, and some of the associated paleoenvironmental circumstances. None of these dimensions alone answers the question of dinosaur origins, and they sometimes provide conflicting implications. Since Dinosauria was named, one or another set of questions has historically dominated academic discussion and research. Paradigms have shifted substantially in recent decades, and current evidence suggests that we are due for more such shifts. I suggest two changes in thinking about the beginning of the “Age of Dinosaurs”: first, the event that we call the (phylogenetic) origin of dinosaurs was trivial compared to the origin of Ornithodira; and second, the “Age of Dinosaurs” proper did not begin until the Jurassic. Re-framing our thinking on these issues will improve our understanding of clade dynamics, timing of macroevolutionary events, and the effects of Triassic climate change on terrestrial vertebrates.

Five generations of structures (F1–F5), excluding faults, can be recognised in granitoid and trondhjemitoid migmatites with quartzofeldspathic neosome development associated with F1–F4 structures. Areal variation in metamorphic grade is shown by the zonal development of muscovite-sillimanite, potassium feldspar-sillimanite and potassium feldspar-cordierite assemblages in the palaeosomes. The climactic metamorphism, associated with MS2–MP2 mineral growth, occurred at between 675°C, 4 kb and 825°C, 6·5 kb. These pressure-temperature conditions are consistent with at least some neosome development having resulted from partial melting. The occurrence of a relatively shallow metamorphic geotherm and the resultant products are assessed in relation to metamorphic conditions known from elsewhere in the Svecokarelides.

The Eleonore Bay Supergroup (EBG) is a 16 km-thick shallow-water sequence of Neoproterozoic age that is preserved within the East Greenland Caledonides in several tracts, surrounded by crystalline gneisses and schistose supracrustal rocks. The apparent downward transition from non-metamorphic EBG into gneiss gave rise to the classic ‘stockwerke’ hypothesis, in which all the metamorphism was regarded as Caledonian, and differences in grade were ascribed to the ascent of a migmatite front to different levels within the orogen. Field and isotopic studies in the 1970s however revealed that the underlying gneisses and schists had undergone orogenic reworking in mid-Proterozoic time; the EBG–basement contact was then interpreted as an approximately bedding-parallel décollement with apparent lag geometry, that is with EBG cover rocks in its hangingwall.

Recent work in the northernmost EBG tract, at Ardencaple Fjord, has shed light on the problems posed by the basal relationships of the EBG, and together with regional structural and stratigraphic data leads to the following interpretation. There are two regionally important basement-cover interfaces within the East Greenland Caledonides. The earlier one is between Archaean/early Proterozoic gneisses and early Proterozoic supracrustal rocks, which were pervasively deformed in mid-Proterozoic time and form the basement to the Neoproterozoic Eleonore Bay cover sequence. This was deposited on a vast, continually subsiding shelf that is now preserved in East and NE Greenland and Svalbard, and contains Grenville detritus. EBG deposition was terminated by major extensional faulting of Vendian age; the succeeding Tillite Group is interpreted as a syn-rift sequence, presumably associated with the opening of Iapetus.

The EBG–basement contacts that are not late faults are inferred to be extensional shear zones of Vendian age. These were reactivated in compression during the Caledonian orogeny in the Silurian, with metamorphic and fabric convergence, which accounts for the apparent downward transition from sedimentary rocks through schists into gneisses. Caledonian shortening was not large; inversion of the Vendian grabens was incomplete, so that the marginal shear zones retained their lag geometry and large tracts of low grade Eleonore Bay sediments are preserved at the present erosion level, surrounded by Proterozoic basement rocks, within the Caledonian belt of East Greenland.

Ossified skeletal elements within the orbit, such as scleral ossicles, palpebrals, supraorbitals and sesamoids, are widespread across Reptilia, including extant members of Crocodylia, Aves, Squamata and Chelonia. Extant crocodylians lack scleral ossicles, but have a unique palpebral that has recently been shown, through developmental studies, to be an osteoderm in the upper eyelid. Here, we examine the diversity and disparity of the crocodylian palpebral in extant members of Crocodylia and, through the fossil record, trace the origin and evolutionary history of the element throughout Pseudosuchia (all archosaurs more closely related to crocodylians than avians). We show that the crocodylian palpebral originated outside of Crocodylomorpha in early pseudosuchian groups (e.g. Aetosauria, Loricata) and that scleral ossicles are lost in nearly all groups of pseudosuchians, but appear in poposauroids, at least one early crocodylomorph, and some partially or fully marine Crocodyliformes (e.g. thalattosuchians). The morphology and number of palpebrals differs across Crocodyliformes; the presence of two palpebrals is plesiomorphic, but this is reduced to one by Crocodylia. We further recommend the restriction of the term palpebral to the structure in crocodylians and their homologues, but not to the structure in ornithischian dinosaurs.

The skull roof, palate and lower jaw of the seymouriamorph Utegenia shpinari (?Upper Carboniferous–Lower Permian; Kurgalin Formation, Kazakhstan) are described in detail, and a new cranial reconstruction is presented. Important features include: skull slightly longer than broad; elongate nasals; deep, elongate posterior cheek region; long, dorsoventrally deep posterior jugal ramus; flat, recurved, blade-like tabular process; denticle-covered anterior ventral part of pterygoid quadrate ramus; transverse pterygoid flange; low radiating ridges with denticle rows on pterygoid and parasphenoid cultriform process; incipient anterior wedge-like process on posterior end of parasphenoid cultriform process; distinct, robust posterolateral processes of posterior plate of parasphenoid. Degree of skull ossification, ornamentation, and absence of ossified quadrate, articular and endocranium suggest that large Utegenia specimens correspond to larval Discosauriscus. In such specimens, dentine infolding extends for almost half of the crown in premaxillary and largest maxillary teeth, as in late larval/metamorphic Discosauriscus. Preliminary results of a regression analysis through some simple skull measurements indicates that, although the preorbital and interorbital regions elongate isometrically relative to the posterior skull table, they do not show a particularly strong linear correlation with the widening of the skull during ontogeny.

The granites of Hong Kong comprise a variety of assemblages dominated by chemically evolved compositions. They are divided into two suites based on petrographic, geochemical, and age criteria. The oldest and most primitive intrusive units are deformed biotite-hornblende granodiorites and monzogranites of the Lamma Suite. These rocks are characterised by high CaO (1·4-2·7%), and low Nb and Y contents. The Lion Rock Suite (LRS) is dominated by relatively undeformed monzogranite with subordinate quartz syenite and comprises three subgroups. Granites of subgroup I are separated into coarse- and fine- to medium-grained lithologies. The fine- to medium-grained granites are predominantly fluorite-bearing with silica contents ranging from 75·5-78%. They are characterised by high total REE, Ga, F, Rb, Nb, and Y contents and yield a Rb-Sr whole-rock isochron age of 155 ± 6 Ma with an initial 87Sr/86Sr ratio of 0·7101 ± 0·0060 (MSWD = 4·6). Granites of subgroup II comprise a diverse range of compositions (SiO2 = 63–77%) and are characterised by highly variable trace element abundances. Coarse-grained granites yield an age of 148 ± 9 Ma with an initial 87Sr/86Sr ratio of 0·7060 ± 0·0006 (MSWD = 0·1). Granites of subgroup III are moderately to highly evolved (SiO2 = 72·5-77·9%) and the silica-rich compositions are marked by enrichment in Y, Nb, Rb and depletion in Ba and Sr. Rb-Sr whole-rock isochron ages for individual plutons vary from 138 ± 1 to 136 ± 1 and corresponding initial 87Sr/86Sr ratios are 0·7080 ± 0·0002 (MSWD = 1·2) and 0·7092 ± 0·0006 (MSWD = 0·4). Granites of the Lamma Suite and coarse-grained granites of LRS subgroup I are interpreted as synorogenic I-types, whereas those of LRS subgroups II and III are interpreted as late-orogenic to postorogenic, fractionated I-types. Fineto medium-grained granites of LRS subgroup I have distinctive A-type affinities and together with their association with quartz syenite indicate a transition from compressional to tensional tectonics.

1. The integral occurs so frequently in various branches of research that, as far back as 1783, Laplace suggested that it would be useful to tabulate its values for successive ranges of integration. It is employed in investigations on the theories of refraction, conduction of heat, of errors of observation, of probabilities, etc. These are familiar to physicists and need not be dwelt upon.