The following account deals with the systematics and distribution of the fresh-water and terrestrial molluscs of Siberia and Northern Kazakstan. During the open seasons of the years 1932 and 1933 journeys were made through that country, typical areas in several of the great natural regions were examined in some detail, and extensive collections were made. The object of this expedition was to obtain fresh and accurate information regarding the constitution and distribution of the molluscan fauna. During the past one hundred years several scientific papers have appeared which refer to the molluscs of this territory, but despite this the knowledge of this group of animals in Northern Asia has remained in a very unsatisfactory state. This has been due to the collections in the past having been made incidentally in the course of other work, and little or no attempt has been made to evaluate the fauna as a whole. The most thorough investigation so far carried out in this region is that of Westerlund (1877), but his paper was published nearly sixty years ago, and the advances in the study of the mollusca since that time make it essential that some revision and extension of the work should be undertaken. The present paper is one contribution toward that end.

Ovules of Eurystoma trigona sp. nov. are described. Over 330 unpollinated ovules were found attached to a petrified megasporophyll which appears to be a juvenile form of Alcicornopteris Kidston. Each ovule is triangular in cross section and has three wing-like extensions of the integument. None shows a female prothallus. The possibility that Alcicornopteris represents the fertile foliage of Stenomyelon is discussed.

The cranial structures of Protopterus and Lepidosiren are now fairly well known, and especially owing to the investigations of Bischoff, Bridge, Fürbringer, Göppert, Humphry, Hyrtl, Jaquet, Luther, Maurer, Owen, Pinkus, Ruge, and Wiedersheim, on their adult anatomy, and to those of Kerr and Agar on their development.

Some papers on the development of Ceratodus, which I have recently published, suggested the advisability of obtaining further information on certain points, and this became possible owing to the generosity of Professor Graham Kerr, who gave me both larval and adult stages for the purpose.

Some years ago, when studying the electrical organs of the torpedo, I was forced to the conclusion that the nerves supplying the batteries had not been accurately described, and that notwithstanding the statements in the most recent works, the first electric nerve is not derived from the trigeminus. Finding some difficulty in making out the arrangement of the cranial nerves in the greatly specialised torpedo, I directed my attention, first to the skate, and later to certain sharks, more especially to the Greenland shark (Læmargus). I had not proceeded far before I was convinced that we had still much to learn as to the anatomy of the cranial nerves of both the higher and lower vertebrates.

A 49 m complete section through the 288 Ma Lugar Sill obtained from drill cores can be subdivided into nine units. The uppermost four units are teschenitic and are mirror images of the bottom four. A 35 m thick central unit consists of theralite passing down into kaersutite theralite and then picrite. Marginal chilling 'of the units indicates multiple intrusion from the outside inwards. Olivine in the central unit (Fo88–90) encloses Cr-rich spinels and increases in amount inwards to over 50%. Clinopyroxene, kaersutite and biotite show symmetrically increasing Fe/Mg from the centre of the sill outwards. Most major and trace elements vary symmetrically throughout the sill with those in the central unit reflecting mainly olivine distribution but incompatible elements exhibit upward enrichment. Remarkably, the most-evolved rocks in the sill are at its margins. The sill was formed by multiple injections of successively less-evolved teschenitic magmas followed by a larger pulse of theralitic liquid carrying abundant olivine phenocrysts. The amount of olivine in this final pulse increased during emplacement. Subsequent in-situ differentiation in the central unit, with upward enrichment in residual liquid and volatiles, gave rise to lugarites. The various magmas were produced in a lower-level magma chamber by differentiation of a mantle-derived, alkali-rich picritic magma.

Dark limestones in the old quarries at Leny, Perthshire contain sparse beds with tiny fossils. They are poorly preserved and, though barely affected by the Ordovician Grampian Event tectonism, there is some taphonomic distortion and many are corroded along stylolitised horizons. The fauna mainly comprises trilobites of two types, open-ocean miomerids and polymerid shelf dwellers. Miomerids Condylopyge cf. eli and Kiskinella cristata indicate a stratigraphical position equivalent to the base of the paradoxidid Amgan Stage of Siberia; traditionally regarded as ‘Middle Cambrian’. However, the bulk of the Leny miomerids, notably species of Pagetides, are forms described from the outer edge of Laurentia, within the Bonnia–Olenellus Zone, where it is considered to be ‘Lower Cambrian’. The Leny polymerids were likely transported off-shelf and some are conspecific with taxa in the Laurentian allochthonous Quebec and New York successions of the Early–Middle Ordovician (Taconic) Appalachian Orogen. The Leny Limestone and Shale Member of the Keltie Water Grit Formation is part of the Dalradian Supergroup deposited in an off-shelf Caledonide Grampian Terrane of the Humber Tectonostratigraphical Zone, midway between the North American successions and the Greenland Caledonides.

Additional to the trilobites, brachiopods, sponges, hyoliths, bradoriids and a selection of indeterminable organic fragments occur; none of which has any particular age significance.

The sculpture and histology of osteostracan head shields and trunk squamations from the Silurian of Estonia are described, illustrated and used for the identification of disarticulated microremains collected from outcrop sections and numerous drill cores in Estonia and Latvia over the last 40 years. The scattered osteostracan material contains thousands of specimens of scales and shield fragments. The sculpture and histology of species of the previously identified eight genera in the region (Tremataspis, Dartmuthia, Saaremaaspis, Oeselaspis, Aestiaspis, Thyestes, Procephalaspis, Witaaspis) are redescribed, together with Ateleaspis, found in Estonia for the first time. The sculpture on the cornua of several taxa is described for the first time. The new taxa Tremataspis perforata sp. nov., Dartmuthia procera sp. nov., Eldaaspis miklii gen. et sp. nov., Tahulaspis ordinata gen. et sp. nov., Tahulaspis praevia gen. et sp. nov., Meelaidaspis gennadii gen. et sp. nov. and Ohesaareaspis ponticulata gen. et sp. nov. are established, based upon sculpture and histological characteristics of the exoskeleton. The supraoral field with denticles of that field are described for the first time in Oeselaspis pustulata, as is the supraoral plate with buccal denticles in Meelaidaspis gennadii gen. et sp. nov. Thin sections of all taxa (except of Witaaspis) have been studied. This work sheds light on East Baltic osteostracan biodiversity from the Maasi Beds of the Jaagarahu Stage, Sheinwoodian, lower Wenlock up to the Ohesaare Stage, upper Přidoli, Silurian.

Cyclotron lapworthi (Groom, 1902), one of the few British Cambrian bradoriid ostracod species known from a large number of specimens, is redescribed. It has an interdorsum, thus indicating a hesslandonid affinity. The ontogeny of C. lapworthi does not demonstrate a clear distinction of its individual moult stages but does show marked changes in the development of nodes and lobes. C. lapworthi shows wide variation in carapace shape possibly indicating that its valves were thin and relatively flexible. In England and Canada C. lapworthi is restricted to the Upper Cambrian Olenus Zone. C. lapworthi may also occur coevally in the Upper Cambrian of Sweden.

Episodes of high streamwater acidity have been cited in the literature as causal in fish-kills; such episodes are often associated with acid precipitation. An investigation utilising continuous monitoring of both precipitation and streamwater for a remote upland site in SW Scotland is reported and the occurrence of two episodes of streamwater acidification is described. The apparent mechanism for these episodes is one of ion exchange in the catchment soils following precipitation inputs laden with sea-salts. The investigation indicates the potential importance of sea-salts in streamwater acidification within the British context. The data provide insights into the mechanisms of acidification from precipitation input to ftreamwater output.

The first known fossil Ostracoda were collected by the Rev. David Ure from the Carboniferous Limestone of East Kilbride. In 1793 he figured his specimens, describing them merely as “microscopic shells.” Some years later Dr S. Hibbert (1836) described and figured as Cypris scotoburdigalensis some Ostracoda he had collected from the Burdiehouse Limestone near Edinburgh. The most important work on this group of fossils was done by T. R. Jones. In 1866, together with J. W. Kirkby, he gave a short account of previous research, and from 1855 until 1901 published a large number of papers, either alone or in collaboration with J. W. Kirkby, H. B. Holl and others, mainly in the Annals and Magazine of Natural History. In 1927 Dr Hopkins used an ostracod bed for correlation purposes in the Northumberland and Durham Coalfield, and in 1931 W. B. Wright observed that the ostracods show a definite succession of forms. A new species described by Wright as Cytherella foveolata occurs at the top of the Pulchra Zone and may be of zonal significance since it has not so far been recognised in any other horizon.

Three cupules of Eurystoma angulare are described; they bear one, six, and ten attached ovules respectively. The cupules are built up of several terete branches which dichotomise in successive planes at right angles. Where an ovule is borne a small number of dichotomies are adnate basally so forming an ovuliferous syntelome.

The graptolite and conodont biostratigraphy of the latest Darriwilian, Sandbian and early and middle Katian succession on the Yangtze Platform is reassessed based on numerous new fossil collections and previously published data. At least at some localities, the lowermost Miaopo Formation is of pre-Nemagraptus gracilis Zone age (uppermost Pygodus serra and lowermost P. anserinus conodont zones). The rest of this formation (except for the uppermost part, which lacks diagnostic graptolites) has a diverse graptolite fauna of the N. gracilis Zone. The uppermost part of the Miaopo Formation contains few biostratigraphically diagnostic graptolites but the occurrence of conodonts of the Baltoniodus alobatus Subzone of the Amorphognathus tvaerensis Zone suggests equivalence with part of the Climacograptus bicornis graptolite Zone. The conodont succession of the Datianba Formation is virtually identical with that of the Miaopo Formation, confirming that these units are coeval. The lowermost part of the overlying non-graptolitic Pagoda Formation represents the upper A. tvaerensis Zone, and its upper part represents the A. superbus Zone. The occurrence of Dicellograptus elegans in the overlying Chientsaokou Formation (equivalent to the Linhsiang Formation in Yangtze Gorges region) suggests equivalence with the Pleurograptus linearis Zone in Scotland, which is consistent with the relatively non-diagnostic conodont fauna in these Chinese units. The biostratigraphic data are in good agreement with the δ13C chemostratigraphy and permit the establishment of precise correlations with the Baltoscandic and North American successions.

Sensory nerves are divided into two classes, those of general sensibility and those of special sense. The nerves of general sensibility are distributed to the skin, muscles, or viscera, and convey influences to the brain which give rise to sensations of touch, heat, &c., or to those vague sensations, not definitely localised, which we include under the name of the muscular sense. The nerves of special sense are endowed with special and individual physiological properties. When a nerve of this order is irritated in any way, either by mechanical, chemical, or electrical stimuli, an influence is conveyed to the brain which gives rise to the same kind of sensation as that produced by the normal stimulus on the terminal organ. For example, pressure on the eyeball, as shown by Newton and Young, electrical stimulation by a continuous current, as demonstrated by Pfaff, Helmholtz Ritter, Purkinje, Du Bois-Reymond, and Schelske, produce many of the phenomena of vision, including not only the perception of light, but the perception of various colours and tints. But while this is the case, it is equally certain that each terminal organ responds to its normal stimulus. Thus the retina, though capable of stimulation by pressure or electricity, is specially fitted by its histological structure for the reception of those minute vibrations of the ether which constitute light. But while the terminal organ is capable of receiving a most delicate action of the normal stimulus, the nerve in connection with it is not so affected. For example, although the retina is affected by light, the optic nerve is not so, as may be proved by Marriotte's well-known experiment, by which it may be demonstrated that when the image of an external object falls on the entrance of the optic nerve, there is no corresponding sensation. The nerve is thus insensible to the normal stimulus of the sense organ, the retina.

Jan Mayen is so inaccessible and so infrequently visited that very little geological and petrographical work has been done on the island. Some rocks were collected during the Austrian “Pola Expedition” of 1882–3; and these were described by Scharizer as porphyritic olivine basalts, with one example of ægirine-trachyte. Four analyses were given, but their quality is so poor that they are practically useless for scientific discussion. Washington lists only one of these, and that among the analyses of inferior quality. The only modern petrographic work that has been done on Jan Mayen rocks is the description of an olivine-trachyandesite by Dr Holmes accompanied by a first-rate chemical analysis by Dr H. F. Harwood, which forms a valuable addition to the seven new analyses recorded in this paper.

Biting midges (Diptera: Ceratopogonidae) are a large family of flies that commononly appear in Lower Cretaceous to Miocene strata, with over 280 fossil species (4.3 % of the family), belonging to 49 genera (26 extant; 23 extinct). Morphological characters used in the identification of fossil genera and species are identical to those used in studies of extant Ceratopogonidae and, as a result, their potential indicative value is reliable. Two relictual extant genera, Leptoconops and Austroconops, reported from Lower Cretaceous Lebanese amber, are at least 125 million years old. Certain ceratopogonid genera are indicative for the Lower Cretaceous, Upper Cretaceous, Eocene or Miocene. A morphological character indicative for the Upper Cretaceous and Cenozoic is macrotrichia on the wing membrane of adults. Indicator species and genera are reviewed for all amber deposits. Eocene Baltic amber contains the best known fauna of biting midges, with 109 named species. Some genera are indicative of aquatic and semiaquatic habitats (predaceous genera, subfamily Ceratopogoninae), forests with rotting trees (Forcipomyia), sandy sea shore habitats (Leptoconops), a cold boreal climate (Ceratopogon) or warm climates (Nannohelea, Austroconops, Leptoconops, Meunierohelea, Metahelea). Females require a protein-rich meal and are well known for feeding on the blood of vertebrates, but many feed on other things, so this information can help with the interpretation of palaeoenvironments. Washingtonhelea taimyrica Szadziewski, 1996, described from Siberian amber, is transferred to the fossil genus Palaeobrachypogon: P.taimyricus (Szadziewski, 1996), comb. nov. For Serromyia alphea, mistakenly redescribed and illustrated from Eocene Bitterfeld amber (= Baltic amber) by Szadziewski (1993), a new name – Serromyiaerrata Szadziewski, nom. nov. – is proposed.

During Lateglacial cold periods, permafrost developed throughout Scotland, sediment-mantled slopes were extensively modified by solifluction and other forms of periglacial mass movement, large-scale sorted patterned ground formed on plateaux, and enhanced rockfall resulted in talus accumulation below cliffs. Most rock-slope failures occurred within five millennia following ice-sheet deglaciation, with many probably triggered by uplift-induced earthquakes; numerous debris-free scarps represent sites where Lateglacial rockslide debris was excavated by glaciers during the Younger Dryas Stade (∼12.9–11.7 ka). Sandar and outwash fans deposited by glacial rivers during ice-sheet retreat were incised to form high-level terraces. Under the cool temperate but relatively stable climate of the Holocene, solifluction and patterned ground formation continued to operate on high ground, though accumulation of high-level aeolian deposits on most mountains was terminated by erosion during the Little Ice Age. Drift-mantled slopes and talus slopes have been extensively eroded by translational failures and debris flows, the latter depositing debris cones on upland valley floors. The incidence of Holocene rockslides has been much lower than during the Lateglacial period. Dating of alluvial deposits and low Holocene terraces suggests no consistent pattern of Holocene floodplain evolution: incision has apparently dominated in the Highlands, aggradation in the lowlands, and floodplains in the Southern Uplands have asynchronous histories of incision and aggradation. Studies of floodplain behaviour over the past 200–300 years suggest that though major floods rework the floodplains of braided and piedmont rivers, there is no tendency towards net floodplain aggradation or incision. Most valley-side alluvial fans accumulated episodically in the last 4000 years, many in response to lowering of hillslope stability by woodland clearance. For many postglacial landsystems, disentangling the effects of declining paraglacial sediment supply, climate change and local influences (extreme rainstorm events or anthropogenic impacts) remains challenging.

A petrified lycopod found in a loose block of calciferous sandstone from the Cementstone Group in Berwickshire possesses a rooting stem-base similar to others previously assigned to Lepidodendron calamopsoides (Long 1964) but it shows continuity with a dichotomously branched stem about 15 cm. long, lacking leaves, but otherwise resembling Oxroadia gracilis (Alvin 1965). The diagnosis of Lepidodendron calamopsoides has been emended to include only axes bearing lepidodendroid leaf cushions as previously described. The new specimen, and others with like roots are tentatively assigned to Oxroadia gracilis Alvin.

New U/Pb results by cathodoluminescence-controlled single zircon dating of rocks from the High Tatra Mountains (Slovakia) constrain ages for the protolith at 2Ga for the granitoids and 3 Ga for the Koncistá migmatite. Concordant single zircon ages date the intrusion of the migmatite precursor at 3567 Ma and the migmatisation at 332 ± 5 Ma. The intrusion of this precursor corresponds with the major granite intrusion in the Western Tatra Mountains. The geodynamic scenario at this time is described as slab detachment of subducted oceanic crust at the active continental margin of Gondwana. The resulting upwelling of asthenospheric mantle brought enough heat for the anatexis of old metasediments and the production of new H- to S-type granites. High Tatra diorites have an intrusion age of 341 ± 5 Ma, constrained by a concordant single zircon age. This age marks the beginning of the Variscan collision of the two convergent continents Laurasia and Gondwana. The intrusion of granites in the High Tatra was confirmed by concordant data at 314 ± 4 Ma, documenting the final stage of the Variscan continent collision.

The unusually fine stem which forms the subject of this paper was found by Mr T. Kerr, of Edinburgh, in rocks of Calciferous sandstone age exposed in a railway cutting at Dalmeny, Linlithgowshire. Mr James Bennie, of the Geological Survey of Scotland, called the attention of Mr Kidston to the fossil, and the latter very generously placed part of the specimen in the hands of one of us for investigation.

The stratigraphical succession of the Jurassic rocks of Eathie (Cromarty) is described and a list of the fossils collected by the writer from the Kimmeridgian beds given. The fauna, which is of mixed Boreal and Mediterranean affinity, shows that the strata belong to the three basal Eo-Kimmeridgian ammonite zones proposed by Spath. The occurrence of an abundant microfauna is recorded and the palæontology of the varied molluscan forms is discussed. Three new lamellibranch species are described. A short account of the Upper Oxfordian beds which outcrop at Bow Buoy Skerry, 1 mile south of Eathie, is given.