Liquidus phase relationships at H2O-saturated and -undersaturated conditions and 2 kbar in the systems Qz-Or-Ab (SiO2-KAlSi3O8-NaAlSi3O8), Qz-Or-Ab-Al2O3, and subsystems are compared and discussed. In the peraluminous systems (i.e. when melts are saturated with respect to mullite) the liquidus temperatures are lowered by 40-55°C for compositions in the quartz primary field and by 15-25°C for cotectic compositions. The composition of the Qz-Ab eutectic and of the minimum are slightly shifted towards more Qz-rich compositions (minimum composition at P(H2O) = 2 kbar in the system Qz-Or-Ab-A12O3, saturated with respect to mullite: Qz40Or23Ab37). In melts saturated with sillimanite or mullite, the effect of high Al content may be lower for the Qz-Or than for the Qz-Ab eutectic.

The depression of the liquidus temperatures may be partly related to the higher H2O solubility in melts saturated with respect to mullite. The solubility of H2O in a melt with a composition of Qz28Or34Ab38 at 2 kbar and 800°C is 5·77 ± 0·15 wt% H2O and 6·36 ± 0·30 wt% H2O in a melt with the same Qz/Or/Ab proportions but saturated with respect to mullite.

The effect of high Al contents on the Mg and Fe contents of Ca-free granite melts was investigated at 775°C-3 kbar (melts coexisting with phlogopite), and at 820°C-2 kbar (melts coexisting with biotite and spinel), under NNO buffer conditions. Less than 0·15 wt% MgO is incorporated in subaluminous melts coexisting with phlogopite, whereas peraluminous melts (2·9 wt% normative corundum) contain 0·6–0·7 wt% MgO. A similar behaviour of the MgO content is observed for melts coexisting with biotite. In contrast, no significant effect of high Al contents on the FeO content of melt coexisting with biotite was observed. This suggests that the Fe/Mg ratio may be significantly lower in peraluminous than in subaluminous granitic melts.

The Lu-Hf and Re-Os isotope systems have been applied sparsely to elucidate the origin of granites, intracrustal processes and the evolution of the continental crust. The presence or absence of garnet as a residual phase during partial melting will strongly influence Lu/Hf partitioning, making the Lu–Hf isotope system exceptionally sensitive to evaluating the role of garnet during intracrustal differentiation processes. Mid-Proterozoic (1·1–1·5Ga ) ‘anorogenic’ granites from the western U.S.A. appear to have anomalously high εHf values, relative to their εNd values, compared with Precambrian orogenic granites from several continents. The Hf-Nd isotope variations for Precambrian orogenic granites are well explained by melting processes that are ultimately tied to garnet-bearing sources in the mantle or crust. Residual, garnet-bearing lower and middle crust will evolve to anomalously high εHf values over time and may be the most likely source for later ‘anorogenic’ magmas. When crustal and mantle rocks are viewed together in terms of Hf and Nd isotope compositions, a remarkable mass balance is apparent for at least the outer silicate earth where Precambrian orogenic continental crust is the balance to the high-εHf depleted mantle, and enriched lithospheric mantle is the balance to the low-εHf depleted mantle.

Although the continental crust has been envisioned to have exceptionally high Re/Os ratios and very radiogenic Os isotope compositions, new data obtained on magnetite mineral separates suggest that some parts of the Precambrian continental crust are relatively Os-rich and non-radiogenic. It remains unclear how continental crust may obtain non-radiogenic Os isotope ratios, and these results have important implications for Re-Os isotope evolution models. In contrast, Phanerozoic batholiths and volcanic arcs that are built on young mafic lower crust may have exceptionally radiogenic Os isotope ratios. These results highlight the unique ability of Os isotopes to identify young mafic crustal components in orogenic magmas that are essentially undetectable using other isotope systems such as O, Sr, Nd and Pb.

A new genus and species of felid, Ginsburgsmilus napakensis, is described from Napak, Uganda. Material from Songhor, Kenya, previously identified as Afrosmilus turkanae by Schmidt-Kittler (1987) is assigned to this species. A new species of Afrosmilus, A. hispanicus, is described from Artesilla, Spain. These new felid species combine sabre-tooth canines of maochairodont type with cheek teeth similar to those of Pseudailurus. Phylogenetically they are close to Afrosmilus turkanae which shows a greater specialisation towards markedly machairodont forms. On the basis of dental features, we propose a close relationship between these two genera (which we group into the new tribe Afrosmilini) and the tribe Barbourofelini (Sansanosmilus and Barbourofelis), the transition between the two being represented in the fossil record by Prosansanosmilus peregrinus Heizmann et al. 1980.

An analysis of swimming in living crustaceans is presented in order to elucidate the range of ways this function has been achieved, and to reveal the principles which constrain it. The study focuses on Gnathophausia ingens, a primitive, bathypelagic malacostracan that swims with thoracic exopods and pleopods. These structures consist of a muscular peduncle and one or two flagella that are fringed with setulate setae. The basic motion is rowing with the limb and setal fan extended on the power stroke and flexed on recovery.

A survey of other crustaceans shows that rowing with this type of swimming structure dominates throughout, although paddles often replace the flagella. Particularly pervasive is the large relative area of setae, whose effectiveness must stem from the ability to extend and flex passively and from the high drag generated on the power stroke by the setules at low Reynolds numbers.

A review of reconstructions of Palaeozoic trilobites and marrellomorphs reveals the likelihood that if swimming was the function of the exites, they operated inefficiently or were employed in other methods as well. Sculling and drag reduction on the recovery stroke through feathering rather than flexion are possible alternatives. The more common occurrence of paddle-like limb shafts and blade-like marginal structures in other Palaeozoic arthropods is also noted.

A Large number of structurally preserved lycopsid axes from the Lower Carboniferous of Scotland are described and designated as a new genus and species. A comparison of this genus with other lycopsids is followed by a discussion of the development of the secondary cortex, and several other interesting structural features.

In the paper on the sensory canals of Læmargus, communicated to the Royal Society in July last, it was pointed out that the arrangement of the sensory canals differed considerably in the Batoidei from that in Selachoidei, and it was mentioned that the sensory canals of the skate would be next described.

The skate has been selected chiefly because the sensory canals are more typical than in the torpedoes and the whip and sting rays. In the torpedoes some of the canals are in a vestigial condition; while in the rays proper they have in most species undergone great specialisation. But another reason is, that an account of the development of the lateral sense organs in the skate is likely ere long to be published; and, further, the skate will be more easily obtained and kept under observation than the rays, when physiologists eventually direct their attention to the lateral sense organs of Elasmobranchs.

Animals can respond in three main ways to environments that change and deteriorate. They can cope with their inherent physiological flexibility, evolve or adapt to new conditions, or migrate away to areas consistent with survival. The main factors dictating survival are the rates of change and capacities of species to cope. Articulated brachiopods are known as a group that employ low energy solutions and exhibit slow rates in life histories characters, especially in growth and metabolic rates. This way of life carries with it a range of consequences, including poor abilities to raise metabolic rates to perform work. This brings with it poor abilities to cope with elevated temperature. Slow growth, deferred maturity and low feeding rates make them less likely to produce novel adaptations compared with other marine invertebrate taxa. Being largely restricted to hard substrata and low energy supply environments also makes it harder for them to migrate to new sites compared to other groups, because of the large geographic distances between colonisable areas. The only clear area they may have that gives them advantages is in the flexibility of their larval release strategies, where settlement can be from very short, millimetre-scale distances to hundreds of kilometres.

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.

The stem, Buteoxylon gordonianum gen. et sp. nov. was found in stratified ash-beds at Oxroad Bay, near Tantallon Castle. It consists of a terminal region, about 12 cm in length surrounded by 38 petioles borne at acute angles on the stem in a ⅖ phyllotactic spiral. The stelar anatomy resembles that of a Calamopitys with a mixed pith. The petiolar bundles, however, have a distinctive T-shape in cross-section unlike any known species of Calamopitys.

Associated with this fossil stem are numerous seeds of Tantallosperma setigera gen. et sp. nov. These are radially symmetrical, with four (rarely five or six) integumental lobes joined at grooves on the body of the seed but free apically where they bear numerous bristle-like hairs. The funnel-shaped salpinx is only slightly narrower than the lagenostome. Enclosed spherical pollen grains have a trilete mark and measure 60 μ in diameter. The average dimensions of the seeds are 5·9 × 1·1 mm.

The Cumacea and the Tanaidacea constitute branches from the line leading from some primitive Mysid and terminating in the Isopoda. This conclusion is founded on a consideration of purely morphological facts, and it is therefore of interest to study the feeding mechanisms of these groups in order to find out whether they show any possibility of having been derived from the type exhibited by the primitive Mysid (Cannon and Manton, 1927, and Manton, 1928).

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 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.

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.

Whatever may be the worker's views on the origin of the Stegocephalia, and on the relation of the various divisions of the Pisces to one another and to the Amphibia, he cannot but agree that a knowledge of the anatomy and of the embryology of the Polypterini is of paramount importance to all those whose research or teaching is concerned with the evolution of the Vertebrata. So he will understand my pleasure when, through the kindness of Dr F. F. Bond, I was able to obtain from Old Calabar a number of specimens of the less-known genus of the Polypterini, Calamoichthys, which were so well preserved as to be excellent for dissection and, as a whole, quite good for histological detail.

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.

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.

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.

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.

The lichens growing on gravestones in 142 Scottish graveyards have been examined. Measurements were restricted to Section Rhizocarpon thalii. These data permit the development of lichenometric growth curves on acidic igneous, basic igneous, sandstone and slate substrates in most areas of Highland Scotland. The colonisation of gravestones, which is extremely erratic, takes place after a minimum of eight years. The ‘great period’ of growth lasts for approximately 20 years after the erection of the gravestone. The lichen factor (growth after 100 years) is correlated with the growth after 25 and 250 years indicating that it is a representative index of the growth rates. Growth rates are non-linear, decreasing with time. Calculated lichen factors for acidic igneous substrates range from 33 to 104 mm. The distributions of different types of gravestones are non-uniform in both time and space, making the comparison of growth rates on different rock types impractical. The results indicate that there may be a gradual decrease in the growth rates from W to E, reflecting the decreasing maritime influence towards the E.

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.