The general relationships of the caudal scales in Adpenser sturio and Acipenser ruthenus are considered together with a detailed description of the structure of the scales and corium in A. ruthenus, and a new staining method using purpurin counterstained with aniline blue for differentiating dermal structures in sections is described. A comparison of the caudal scales of sturgeons with those of palæoniscids indicates considerable agreement in form and arrangement between them. Evidence is presented to show that the caudal scales in sturgeons and palæoniscids are distinct from the general body covering of scales, and evidence points to a similar, though reduced, squamation in Lepidosteus and possibly in Polypterus. The importance of the caudal scales in protecting the internal organs in the epichordal lobe of the tail and the significance of the boundary between the body and caudal scales as a hinge for tail flexure is discussed.

The paper provides the first detailed geological description of a portion of the Grampian Highlands between Glen Roy in the west and the Monadhliath Mountains in the east. Moinian metasediments comprising thick granulites (Eilde Flags = Central Highland Psammitic Group) followed by a variable series of pelites and impersistent quartzites (Monadhliath Schists = Transition Group) are succeeded by Dalradian Limestone (Kinlochlaggan or Ballachulish Limestone = Basal Calcareous Group). The Monadhliath Schists are shown to be stratigraphically equivalent to those of Lochaber below the Ballachulish Limestone.

Structurally the area consists of north-easterly anticlines and synclines which are generally isoclinal and often overturned. Many formational junctions are clearly stratigraphical, but the point is discussed whether tectonic contacts (slides) may also be present. Most of the metasediments are of garnet grade, but in the east there is a poorly-developed kyanite zone, and a well-developed sillimanite zone. The high-grade zones are related to a major migmatite and pegmatite belt (the Strathspey Complex); another pegmatite belt occurs farther west around Loch Laggan. Post-tectonic granite, quartz-diorite, diorite and appinite intrusions are also present. The district is traversed by several important north-easterly faults which are later than both the metasediments and the intrusions.

Arthur's Seat is the remains of a dissected Lower Carboniferous volcano, from which were erupted a series of basaltic rocks representative of the province to which it belongs. The rocks occur as lavas, intrusions and tuffs, and include basalts of Dalmeny, Jedburgh, Dunsapie, Craiglockhart and Markle types, in addition to mugearite. For convenience the basalts of Dunsapie type have been subdivided into Normal and Feldspathic varieties.

The volcano has been remapped; some minor departures from the six-inch Geological Survey map are recorded and certain changes in the numbering and classification of the lavas have been made.

The petrographic characters of the various volcanic rocks are described in detail, with modal and chemical analyses. The composition of the parental magma of the volcano was probably very similar to that of Normal Dunsapie basalt. Markle and Craiglockhart types were produced as complementary differentiates of the parental liquid by a process of gravity differentiation, in which sinking of ferromagnesian crystals, particularly augites, played an important part. The basalts of Dalmeny and Jedburgh types, which in Arthur's Seat have strong chemical resemblances, probably represent only slightly differentiated parental magma. Concentrations of soda-rich volatiles produced intense albitisation in the Markle basalts and the mugearites. It is considered that the mugearites of Arthur's Seat crystallised initially as Jedburgh or Dalmeny types, and were altered to their present state during a deuteric phase.

An attempt has been made to reconstruct the eruptive history of the volcano. The magma source appears to have been replenished with parental magma at least twice during the period of activity. The first and last eruptions were of Dunsapie basalt; the albitised products appeared at a fairly late stage.

It is generally believed that in mammals the impulse for cardiac contraction is conveyed from the atria to the ventricles by the atrioventricular bundle and its branches. This belief is mainly based on the A-V. dissociation which is found to follow experimental injury of the bundle. Since the bundle contains nerves, as well as specialized muscular elements, these experiments do not conclusively prove which structures, nerves or muscle, actually conduct the impulse. In the dog it has been previously shown that the right limb of the bundle is not usually accompanied by nerves, and in the present work the attempt was made by means of very small incisions to cut the muscle (Purkinje) fibres of the limb without damaging nerves in the ventricular septum, the effect on the electrocardiogram being noted. In 5 out of 38 perfused hearts of dogs the experiment was successful, and resulted in a significant delay in the contraction of the right ventricle relative to that of the left. The experiments also revealed that very considerable damage can be inflicted on the nerves in the ventricular septum without altering the electrocardiogram, so long as the limb itself is not injured. The results are regarded as providing direct evidence that the cardiac impulse in the dog is transmitted to the right ventricle by the muscular elements of the right limb of the bundle, and it is submitted that there would seem to be no valid reason for supposing that conduction throughout the A-V. bundle and its limbs is other than myogenic.

The Leadhills–Wanlockhead mining field is situated within a synclinorial belt of greywackes, bounded to the north and south by anticlinoria in which lower stratigraphical elements are exposed. The universal strike is N.E.–S.W. The southern margin of the northern anticlinorium is delimited by a strike thrust fault, inclined to the north-west. The shear zone caused by this thrust is considered to be the principal structural feature governing the localization of the ore deposits.

The complex N.E.–S.W. folding and faulting, imposed during the Caledonian orogeny, is crossed by a series of intersecting joints, whose average strike is N.N.W. The majority of the mineral veins also trend N.N.W. The formation of these discordant structural features under Caledonian stress is demonstrated by the presence of N.N.W. trending Caledonian dykes.

Sinistral movement along the joint pattern, ascribed to a reorientation of the “Caledonian” stress towards an “Hercynian” direction, resulted in the formation of open spaces on the more north-westerly trending members of the joint system in the greywacke belt. This feature is considered to be the secondary structural control responsible for the localization of the ore deposits.

Fifty-seven minerals were identified from the deposits. Fifteen of these minerals had not been previously recorded from the locality, including (1) a new chromian mineral; (2) a new variety, chromian leadhillite; (3) a mineral previously recorded only as an artificial product, lead hydroxyapatite; (4) phœnicochroite, not previously confirmed in the British Isles.

Two periods of mineralization were distinguished. The first consisted of quartz veins with which are associated small amounts of gold, pyrite and muscovite, tentatively assigned to the Caledonian orogeny, and the second comprised the lead-zinc mineralization. The paragenetic relationships of the primary minerals of the lead-zinc mineralization indicate two generations of sulphides; the second generation is accounted for by reprecipitation of elements derived from the replacement of the first generation by late stage quartz. A study of the distribution of elements through the paragenesis suggests that some elements were derived from other than a magmatic source, and that contamination has probably played a considerable rôle in the control of the character of the gangue minerals.

Evidence that the mineralizing solutions had a deep-seated origin is provided by the mineral zones and the geochemical character of the deposit. Emplacement of the minerals took place at a temperature of the order of 143°−281° C, and a depth of the order of 2000–4000 feet below the surface.

The Leadhills–Wanlockhead deposits are related to other lead-zinc deposits in Britain. On the basis of geochemical assemblage and the relation to igneous activity, it is concluded that the deposits were probably derived from the top of the tholeiitic crustal layer and the base of the granitic crustal layer, and were genetically associated with the Hercynian orogeny.

Details of the anatomy of the heart and the great vessels are recorded in the following genera of prosimian Primates, Loris, Arctocebus, Perodicticus, Galago, Galagoides, Hapalemur, Lemur, Lepilemur and Propithecus, and comparison made with previously published data on Nycticebus. Special attention is drawn to the proportions, shape and mode of branching of the systemic aorta, which is of typical lemurine pattern in all but Loris and Propithecus. In the heart, attention is paid particularly to the valvular arrangements in the right atrium, where much variation has been found; to the number of pulmonary veins entering the left atrium, also a variable feature; to the internal and external morphology of the ventricles and the valvular arrangements therein. The presence of an os cordis is recorded for the first time in any Primate (viz. in Loris), and the occurrence is mentioned of “brown” (glandular) fat sub-epicardially in Loris. The significance is discussed of the principal anatomical features.

In a new synopsis of the family Limapontiidæ the differences between Limapontia capitata and L. depressa, which may sometimes be mistaken for one another, are specially noted. These two species and Acteonia cocksi, the remaining member of the family, are sap-suckers that feed on the cell contents of green filamentous algæ. The cells are slit open one at a time by the leading tooth of the radula and their contents drained. The host plants of A. cocksi and L. capitata are marine Cladophora spp.; L. depressa feeds on Vaucheria. The size of the buccal mass varies according to the host plants. The subterminal position of the anus in L. depressa is an adaptive feature. The reproductive system of A. cocksi is described and compared with those of the other two species. During copulation both A. cocksi and L. capitata transfer sperm by hypodermic impregnation: sperm are injected by means of a penial style into a closed bursa copulatrix. The bursa of L. depressa opens to the exterior by a short duct and the penial style functions as a conducting pipe. Reasons are given for suppressing the genus Acteonia, Quatrefages, and including A. cocksi in the genus Limapontia, Johnston.

A Brief description of the early stages of floral organogenesis in Primula bulleyana is followed by an account of the formation of flowers from experimentally incised primordia. The nature of the floral parts that develop alongside a median incision is related to the developmental stage of the flower primordium at the time of its bisection. The observations are discussed with reference to the determination of the parts of the flower.

The changes in the vascular pattern of the pregnant rat uterus at placental sites and the intervening areas, have been studied radiologically and by injection techniques during the period of pregnancy. A description is given of the development and final pattern of the maternal placental blood channels. From the 15th day onwards wide variations are found in the vascular filling of placentæ after arterial injection. Possible mechanisms for the control of blood flow to placental sites are discussed.

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.