St Kilda (Pl. V), the largest of a group of four islands located some 50 miles west of Harris in Latitude 57° 49′ N., Longitude 8° 34′ W., has an extreme length and breadth of 2½ by 1¾ miles and a circumference of about 8¾ miles. The highly indented coast-line is guarded by almost impregnable cliffs except in the Village Bay or Loch Hirta where there is a strip of sand a quarter of a mile long backed by a great storm-beach. The two principal inlets of the sea, Village Bay or Loch Hirta, and the Glen Bay open to the south-east and north-west respectively.

In order to study the ecology of intertidal plants and animals it is desirable to choose a coast-line which is as simple as possible. When numerous factors vary simultaneously it is impossible to decide which of them is responsible for any change which may occur in the flora and fauna. The complexity of a shore which is ravined or boulder-strewn makes ecological work difficult. Unfortunately, certain major influences, such as wave action, involve a whole complex of subsidiary effects, so that the perfect locality, where each environmental factor would be found to vary in turn independently of all the other factors, cannot exist.

The Great Tonalite Sill (GTS) of southeastern Alaska and British Columbia (Brew & Ford 1981; Himmelberg et al. 1991) is one of the most remarkable intrusive bodies in the world: it extends for more than 800 km along strike and yet is only some 25 km or less in width. It consists of a belt of broadly tonalitic sheet-like plutons striking NW–SE and dipping steeply NE, and has been dated between 55 Ma and 81 Ma (J. L. Wooden, written communication to D. A. Brew, April 1990) (late Cretaceous to early Tertiary). The sill (it is steeply inclined and rather more like a “dyke”) is emplaced along the extreme western margin of the Coast Plutonic and Metamorphic Complex (CPMC), the high grade core of the Western Cordillera. The CPMC forms the western part of a group of tectonostratigraphic terranes including Stikine and Cache Creek, collectively known as the Intermontane Superterrane (Rubin et al. 1990). To the W of the GTS, rocks of the Insular Superterrane, including the Alexander and Wrangellia terranes and the Gravina belt, form generally lower metamorphic grade assemblages. The boundary between these two superterranes is obscure but it may lie close to, or be coincident with, the trace of the GTS.

A new taxon of probable early gymnosperms is described from permineralised specimens showing excellent preservation of the tissues, from the late Lower Carboniferous (Dinantian), Brigantian, deposits of the Midland Valley of Scotland. Stanwoodia gen. nov., represented by the single species S. kirktonensis sp. nov., shows the combination of a primitive protostelic organisation with a dense secondary wood. It closely compares to the enigmatic genus Bilignea which was formerly referred with some reservations to the Cordaitales. Another interest of the new plant concerns the excellent preservation of the phloem with at least three different types of constituent cells including fibres. Stanwoodia also exhibits the oldest well-documented evidence of a sequent periderm or rhytidome in fossil plants.

The Early Tertiary basalt plateau of the Faeroe Islands is cut by dykes and sills. Chemical analyses show a two-fold division of the intrusive rocks into a group of low-TiO2 (0·73–1·93%), MORB-type tholeiitic basalts and a group of high-TiO2 (2·09–3·90%) tholeiitic basalts. The low-TiO2 group comprises about 15% picrites and olivine-phyric basalts and 85% plagioclase-phyric basalts, and shows a chemical range largely explicable in terms of low-pressure fractional crystallisation of olivine ± plagioclase ± clinopyroxene. The high-TiO2 group is strongly dominated by plagioclase-phyric basalts with only few olivine-phyric compositions. The chemical trends are less regular than those formed by the low-TiO2 basalt dykes and a number of subgroups may be identified on the basis of bulk rock chemistry. Dykes belonging to a specific subgroup were probably fed from the same magma chamber.

Petrographically and chemically the dykes and sills are clearly related to the upper 2·5 km of the lava sequence. Field evidence suggests that some of the dykes were contemporaneous with the exposed lavas, while other dykes and the sills were intruded in response to a slight doming of the plateau during the final stages of volcanic activity. Our investigations demonstrate that high-TiO2 and low-TiO2 magmas were both emplaced until the very end of magmatism, with the latter being mainly concentrated in the northern part of the archipelago. We briefly sketch a possible relationship between the supposed NE-Atlantic mantle plume, the distribution of the various magma types and the location of the Early Tertiary continental splitting zone north of the islands.

The Moffat Shale Group is a condensed, variable and partly pelagic sequence of mudrocks of Llandeilo—Llandovery age. The sequence has a five-fold lithological subdivision based mainly on the occurrence of grey mudstones within a succession otherwise dominated by fully euxinic black graptolitic mudrocks. Associated with the black mudrocks, especially in the Llandovery, are metabentonite beds which achieve a climax, both in thickness and in number, within the top quarter of the mudrock sequence. A geochemical and mineralogical study has confirmed a volcanic origin for the metabentonites. Major element data highlight a carbonate-dominated environment above the gregarius—convolutus Zones boundary. Phosphorus levels reach a peak at the same boundary, as well as at the Caradoc—Ashgill boundary where phosphorite horizons are known from Wales and Norway. Immobile trace elements have highlighted regular changes in source magma composition. Prolonged periods of crystal fractionation in magmas of intermediate composition gave rise, on eruption, to large volumes of silicic ash which had a deleterious effect on graptolite species and led to local extinctions. Regular fluctuations in ash composition from silicic to intermediate are ascribed to alternating fractionation and magma mixing cycles.

The existence of a basement of granulite beneath the Midland Valley is supported by investigations of inclusions in volcanic rocks and the geophysical studies of the LISPB experiment. To establish age constraints for this basement, a compilation is presented of available Rb–Sr whole-rock, common lead, U–Pb zircon and Sm–Nd radiometrie data for crystalline rocks in Scotland from the earliest recognised crust (c. 2900 Ma) to 380 Ma (“end” of Caledonian orogeny) including xenoliths in volcanic vents and boulders in conglomerates.

For rocks within the Midland Valley, isotopic data provide four lines of evidence. (1) An upper intercept U–Pb age of c. 1700 Ma for detrital zircons from a lower Palaeozoic greywacke from Dalmellington corresponds to a late stage of the Laxfordian orogenic episode (early Proterozoic) with possibly some overprinting during the Grenvillian episode (mid Proterozoic). (2) The common lead composition of the Distinkhorn granite suggests the participation of early Proterozoic basement during granite emplacement. (3) For xenoliths from the Carboniferous Partan Craig vent, one gives a Sm–Nd CHUR model age of 1180 ± 55 Ma, a second yielded a Sm–Nd garnet—potassium feldspar age of 356 ± 6 Ma and an upper intercept U–Pb age from zircons from the third is c. 2200 (± 240) Ma; for xenoliths from other vents, an Rb–Sr whole-rock isochron of 1101 ± 63 Ma and an Sm–Nd model age of c. 1100 Ma arerecorded. (4) A linear array corresponding to an apparent age of 770 ± 180 Ma on a Pb–Pb isochron diagram for Tertiary igneous rocks of Arran points to an underlying basement of late Precambrian orthogneiss.

The existence of basement made of products of the Grenvillian episode, or predominantly so, similar to the basement N of the Highland Boundary fault, is not inconsistent with the available evidence. However, zircons and other rock components appear to have an ultimate Lewisian provenance. At least in parts, there is also a strong late Proterozoic imprint. Further studies are required for an unequivocal solution.

Restoration of the morphology of Angustidontus seriatus Cooper, 1936 based on complete specimens from the Famennian of Nevada and Poland, supports its affinity to the coeval alleged decapod Palaeopalaemon and suggests eocarid (possibly also peracarid) affinities. Predatory adaptation of the thoracopods and the relatively short pereion make this crustacean only superficially resemble the archaeostomatopod hoplocarids, because the large grasping appendages of Angustidontus represent the first, rather than second, maxillipeds and acted in the opposite direction: downward. Another similar adaptation of the antennae in the Viséan Palaemysis suggests a widespread adaptation to predation among early eumalacostracans. The large sample collected from the Woodruff Formation of Nevada permits biometric characterisation of the grasping maxillipeds of Angustidontus, showing that their highly variable morphology should not be used to define species. All previously described species are therefore here synonymised with A. seriatus. Differences in gnathobases of mandibles found in articulated specimens in Nevada, and associated with isolated maxillipeds and articulated specimens possibly representing another unnamed species in Poland, suggest that such mandibles may eventually prove to be taxonomically more significant.

Antarctica has been known as the “keypiece” of the Gondwana supercontinent since publication of Du Toit's 1937 classic book Our Wandering Continents. It is also important to reconstruction of the early Neoproterozoic supercontinent Rodinia. Laurentia, with its circumferential late Precambrian rifted margins, can be regarded as the ‘keypiece’ of Rodinia. The Southwest US–East Antarctica (SWEAT) hypothesis suggested former juxtaposition of the Pacific margins of Laurentia and East Antarctica. Several new lines of evidence support this hypothesis in a revised form, but must be reconciled with opening of the Pacific Ocean basin predating amalgamation, not only of Gondwana, but even of today's East Antarctic craton. The sequence of events is envisaged to have been: (1) formation prior to 1·6 Ga of a craton, including Laurentia and the Mawson craton, that extended from South Australia along the present Transantarctic margin to the Shackleton Range; (2) suturing of southernmost Laurentia to the Kalahari craton along the Grenville, Namaqua–Natal–Maud orogenic belt ca. 1·0 Ga; (3) rifting of the East Antarctic margin (Mawson craton) from western Laurentia ca. 0·7 Ga; (4) pan-African suturing of the Mawson craton to southernmost Laurentia as Gondwana amalgamated, forming the ephemeral Pannotia supercontinent; and (5) end-Precambrian separation of Laurentia as Iapetus opened.

In the seaward direction in an estuary there are usually the following main gradients:—

(a) Increase in osmotic pressure (total salt content, especially chlorides).

(b) Increase in calcium and magnesium content.

(c) Increase in alkalinity.

(d) Increase in winter and decrease in summer temperature.

(e) Increase in light penetration.

There are other gradients of less importance. The first three are dependent on salinity. Thus, from the ecological standpoint, the three important physical observations relative to the study of estuarine life are the salinity, temperature, and light (silt content) gradients.

Ecological studies are directed towards the elucidation of two types of problems:

(i) Characteristics of the physical environment relevant to the distribution of specific forms of life.

(ii) The growth of mixed populations and their interrelations in a homogeneous environment or in a physical gradient.

The present study concerns itself especially with the former, and to a less extent with the latter.

My first knowledge of Stenomyelon Tuedianum was derived from a microscopical preparation in the collection of the late Mr C. W. Peach, A.L.S., which, through the kindness of his son, Dr B. N. Peach, F.R.S., subsequently came into my possession. The specimen was labelled as having been found “near Berwick.”

The Upper Silurian rocks of the Gutterford Burn, in the Pentland Hills, have for some time been known to contain Eurypterid remains, but the fossils procured from these beds—chiefly owing to the exertions of Mr Hardy of Bavelaw Castle, and Mr Henderson, late Curator of the Phrenological Museum—have never been submitted to a thorough examination. When, therefore, by the kind permission of Sir R Murdoch Smith, Director, and Dr E. H. Traquair, Keeper of the Natural History Collection in the Edinburgh Museum, I was given an opportunity of examining Mr Henderson's collection, which was acquired by the Museum some years since, I entered upon the work with the expectation of finding some new and interesting forms which would repay description. My expectations in this respect have been more than fulfilled, as the collection has yielded five undoubtedly new species, one of which I have made the type of a new genus. If to these one adds at least two other new species which are in the collection of Mr Hardy of Bavelaw, and which I hope to have the pleasure of examining and describing at some future time, one is justified, I think, in saying that the Gutterford Burn is unequalled among Eurypterid localities with regard to the variety of forms it has yielded. Unfortunately the bed which has yielded these specimens is limited in extent, and further work on it would entail quarrying operations on a somewhat extensive scale.

In this paper some properties of the functions J[n](x, λ), P[n](x, λ), Q[n](x, λ) will be investigated. These functions are generalised forms of Bessel's and Legendre's Functions.

The sandstone quarry of Corncockle Muir is situated between the rivers Annan and Kinnel, about a mile and half above their confluence, and not quite three miles from the town of Lochmaben in Dumfriesshire. It is near the top of a low, round-backed hill, which stretches about half a mile in a westerly direction, almost in the line of the rivers. This hill rises out of a valley of irregular surface, terminated, at the distance of some miles, on the north and north-west, by a mountainous range of transition rock; on the south by an arm of the same range; and on the east, at a greater distance, by lower elevations, consisting, according to Professor Jameson, partly of floetz-trap and partly of the independent coal-formation. The valley itself is said by the same authority to be of the independent coal-formation, lying on the transition rock, and contains considerable quantities of sandstone interspersed in various parts, and stretching as far as the bottom of the mountains.

Several authors have proposed that granitic melt accumulation and transport from the source region occurs in networks of connected melt-filled veins and dykes. These models envisage the smallest leucosomes as ‘rivulets’ that connect to feed larger dykes that form the ‘rivers’ through which magma ascends through the sub-solidus crust. This paper critically reviews this ‘rivulets-feeding-rivers’ model. It is argued that such melt-filled networks are unlikely to develop in nature, because melt flows and accumulates well before a fully connected network can be established. In the alternative stepwise accumulation model, flow and accumulation is transient in both space and time. Observations on migmatites at Port Navalo, France, that were used to support the existence of melt-filled networks are discussed and reinterpreted. In this interpretation, the structures in these migmatites are consistent with the collapse and draining of individual melt batches, supporting the stepwise accumulation model.

Morphological and physiological features indicate Metriorhynchidae as the only group of crocodylomorphs with a pelagic lifestyle. Some of these features have evolved convergently in several clades of tetrapods secondarily adapted to aquatic life. One striking feature of metriorhynchids as compared to other crocodylomorphs is the morphology of the pelvic region (i.e., ventrally deflected sacral ribs and reduced pelvic girdle), which increases significantly the depth of this region. This morphology, as a whole, resembles that of other viviparous Mesozoic marine reptiles not phylogenetically related to metriorhynchids. We tested two alternative hypotheses of reproductive strategies in this clade: oviparity vs. viviparity. Given the lack of direct evidence supporting one or the other, we explored the use of evidence that may disconfirm either of these hypotheses. Using this counter-inductive approach, we found no cases contradicting viviparity in metriorhynchids, except for their phylogenetic position as archosaurs. A survey of reproductive modes amongst amniotes depicts the evolutionary plasticity of the transition to viviparity, and a widespread occurrence among tetrapods secondarily adapted to a marine life. Assuming oviparity for metriorhynchids implies egg-laying out of the water. However, their postcranial morphology (i.e., features of fore and hind limbs, pelvic girdle, and tail) contradicts this possibility. In this context, we rejected oviparity for metriorhynchids.

In a preceding paper of this series it was pointed out that the smooth branched axes, which are so common in the Middle Old Red Sandstone of Scotland, cannot be assumed to belong to one kind of plant. They were therefore for convenience referred to as Hostimella sp. It was further shown that three distinct types of sporangia were associated with axes of this general type and, on the characters afforded by the reproductive organs, three species were distinguished. These were provisionally retained under the generic name Hostimella, as H. pinnata, H. globosa, and H. racemosa. In the same paper it was mentioned that the linear bodies borne on the peculiar fossil known as Ptilophyton Thomsoni, Dawson, were almost certainly sporangia. This afforded another reproductive structure borne on a vegetative region, which, if found separately, could only be placed in Hostimella sp. Since, as had been pointed out by Kidston, the generic name Ptilophyton is inadmissible for this fossil, it was placed in the purely provisional genus Hostimella as H. Thomsoni. In the present paper the nature of this interesting member of the Scottish Middle Old Red Sandstone Flora will be more fully considered.

The Trawenagh Bay Granite (TBG) is shown to be a tabular pluton with gently inclined contacts that, from anisotropy of magnetic susceptibility (AMS) studies, was emplaced as a series of flow lobes whose geometries indicate that it flowed horizontally towards the W out of late stage adjacent steeply inclined monzogranite sheets of the Main Donegal Granite (MDG). We thus confirm in detail the central broad idea of the Pitcher & Read (1959) model that the Main Donegal Granite fed the Trawenagh Bay Granite. Early TBG flow lobes cut and are cut by deformation associated with the sinistral shear zone in which the MDG lies, thus demonstrating synchronicity of shearing and magmatism. The TBG magma leaked out of the shear zone and emplaced into undeformed country rocks and was probably guided by shear zone splays that die out along its northern and southern margins. At a late stage in the development of MDG, the splays developed from the NNE-trending SW boundary of the shear zone and caused a gap in this structure through which TBG magma was channelled out of the MDG. A review is presented of the last twenty-five years of published and unpublished work on the batholith, showing that the MDG shear zone was a long-lived structure almost certainly in existence before the emplacement of that body, and that four of the contiguous granitiods (Thorr, Ardara, and Rosses, as well as Trawenagh Bay) were all sourced within the shear zone. A new model is presented for the development of the batholith. The pre-existing crustal structure was a deep-seated N12°E fault in the basement to the Dalradian wall rocks of the granites, that was coupled to up to six other more minor WNW-ESE basement faults in the W. A NE-SW-trending sinistral shear zone was initiated at the end of the Caledonian orogeny, as calc-alkaline and deep-seated appinites were generated in the area. This shearing activated the pre-existing structures at the current crustal level, and the N12°E structure acted as a continental transform fault which allowed the dilation needed to facilitate the wedging space requirements of the MDG and the other units in the shear zone, as well as transferring regional sinistral shear through the system. The Thorr and Ardara plutons were emplaced first into the shear zone and then those magmas leaked out into the adjacent wall rocks: one to form a large laccolith, the other to form a balloon. Steep early MDG complex sheets (granodiorites and tonalities) were emplaced in the shear zone between the Thorr and Ardara emplacement sites. Dilation continued until late stage extensive monzogranite sheets were intruded in the NW and SE of the pluton. One of these probably leaked material westward to form the Rosses laccolith and southwestwards to form the TBG in the final stages of shear zone movement.

The investigations recorded in this communication were begun some years ago, and arose chiefly as the result of two papers published on the Geology of the Forest of Wyre by Mr T. C. Cantrill, B.Sc.

In the latter paper Mr Cantrill, after carefully summarising all the available data respecting the age of the so-called “Permian” of the Forest of Wyre (= Enville), arrives at the following conclusions:—

I. That these “Permian” rocks are of the same age as those at Hamstead in South Staffordshire.

II. That the Hamstead red rocks were shown by their flora to be Upper Coal Measures.