Monthly mean sea-water temperatures in Plymouth Sound, prepared by the Plymouth City Meteorologist, are presented as data for ecological studies in this laboratory. In the last 40 years there has been a rise in mean temperature of about 0·3°C.

In an earlier paper (Wilson & Wilson, 1956) there was described a large-scale stranding, on the shores of Cornwall and Devon in 1954, of the pelagic gastropod Ianthina janthina (L.). Most of the shells then collected were broken, but thirty-six were entire and measurements of these showed that, in spite of considerable variation in the proportion of width to height, the width is proportionately greater in young than in old shells. None of the 1954 shells was less than half an inch high, the majority being considerably higher. Two shells stranded at Sennen several years before, and the figure of one in a paper by Fowler (1947, as I. planispirata Adams & Reeve) were the only specimens less than half-an-inch high available for comparison with the larger ones. The measurements of these agreed with the general conclusion that as the shell grows it becomes proportionately less wide. In the past these variations in shell shape have been responsible for the erection of a number of different species. In order to establish the conclusion firmly it was desirable to examine a collection of young shells.

On 31 March 1957 Mrs M. Hicks wrote from St Agnes, Isles of Scilly, to say that on that day her husband had found eight small Ianthina, six of which had stranded alive on the afternoon's tide, the other two, one of them alive, earlier. Subsequently more were collected. On 8 April Miss Deborah Hicks (age 9) picked up about 130, some of them living, some apparently not.

It has been found that a reagent containing sulphuric acid, ammonium molybdate and ascorbic acid may be used as a single-solution reagent for the determination of phosphate in sea water. Development of the molybdenum-blue colour is complete in 24 h at room temperature and in 30 min at 60° C; the colour is stable for at least 3 days. Beer's law is obeyed closely up to at least 500 μg PO43−-P/1. The salt error is approximately 4% with sea water of chlorinity 19·3%. The interference due to either arsenate or silicate at their concentrations in sea water is negligible.

The heart-bodies and some other tissues of a number of polychaetes have been examined chemically, and the porphyrin pigments from these tissues described. Coproporphyrin III was shown to be present in relatively large concentration in all the heart-bodies, together with traces of coproporphyrin I, a tricarboxylic porphyrin and protohaematin. The body wall of light (pink) and dark (brown) coloured Arenicola and of Amphitrite also contained these pigments in varying amounts. Other non-porphyrin pigments were also seen in the body wall of some animals, the most remarkable being a colourless compound with a bright blue-fluorescence occurring in Flabelligera. Evidence is presented which supports the view that the heart-body is an haematopoietic organ, and the significance of this is discussed. Parallels are drawn between the occurrence of free porphyrins in marine animals and the occurrence of such pigments in porphyrias in man.

The light energy emitted in a flash by single elytra of two polynoid worms has been measured, viz. Acholoë astericola and Lagisca extenuata. Maximal emission occurs at 515 mμ. Mean values for light intensity per flash from 1 elytrum are: Lagisca, 1·8 × 10−10 μJ/cm2 receptor surface at I m ; Acholoë, I·II × 10−8 μJ/cm2 receptor surface at I m. The light emitted in I flash by a single photocyte of Lagisca is 0·12 × 10−12 μJ/cm2 receptor surface at I m. It is estimated that the light from I elytrum of Lagisca could be seen by the dark-adapted human eye at 1·2 m in air.

A spectral emission curve for the light of Pholas dactylus has been determined by means of spectral niters and photomultiplier cell. Emission extends from about 440 to 670 mμ, with a maximum at about 490 mμ. The emission curve is compared with the action spectrum determined by Hecht.

In experiments on four species of barnacles and four species of top-shells, the barnacles were found to be more resistant to high or low temperatures than the top-shells. Among each group of animals the degree of tolerance was related to the geographical distribution of the species and their zonation on the shore. Thus most tolerance of high temperature was shown by species of southern distribution, especially by those occurring at the upper limit of the midlittoral zone, and most tolerance of low temperature by species of northern distribution. Least tolerance of high and low temperatures was shown by species found only in the infralittoral fringe or below low water.

Field measurements of the body temperatures of barnacles and limpets while exposed to the air were made with thermocouples. Under many weather conditions the body temperatures were higher than would be expected from local meteorological values of air temperature. This difference was due to retention of sea temperature by the animals and the rocks and to the heating effects of sunlight.

The results of the laboratory experiments and of the field measurements are discussed together in relation to weather and geographical distribution. It is clear that the temperatures experienced on the shore are well within the tolerance limits of most of the animals, and even exceptional extremes of temperature may have little direct influence on the distribution of adult intertidal animals. Evidence for a causal relation between temperature and distribution must be sought in non-lethal terms such as debilitating effects, or indirectly through competition between species, or in combination with other factors.

An investigation of the adhesive mechanisms in all nine species of the genus Diclidophora has shown that there is a common structure consisting of a pair of hinged jaws operated by intrinsic muscles and also by a more powerful extrinsic muscle which acts on a diaphragm to produce a suction pressure that is converted into a clamping action. This investigation has revealed errors in Cerfontaine's and other descriptions of the anatomy of Diclidophora adhesive organs, but substantiates Cerfontaine account of the adhesive mechanism, and therefore disagrees completely with the more recent account given by Sproston.

In a recent paper (Russell, 1956) I described a new medusa Amphinema krampi from a single specimen. I have now found three more specimens in collections made with a 2 m stramin ring trawl by R.V.Sarsia. Two of these were caught on 13 June 1956 at 48° 29' N., 9° 05' W. with 450 fathoms of wire out; one was a female 7 mm high and the other a male about 5 or 6 mm in height. The third specimen, a male 6·5 mm high, was taken on 4 July 1956 at 47' N., 5° 47' W. with 880 fathoms of wire out. Of the three specimens the female being the best preserved was kept intact; the two males were used for sectioning.

It is now possible to add to my previous description of the species. As in the specimen already described, the umbrellas are crumpled and have their margins turned inwards. In the female, however, it is certain that there is a small apical projection. The radial canals leave the stomach below the lower limits of the gonads so that there are fairly long 'mesenteries'. The marginal tentaculae are six in number in each specimen, two perradial and four interradial. It is possible therefore that the eight which I recorded in my first specimen may have been an abtext-abstract number. The interradial female gonads are irregularly folded and much corrugated. All specimens have exactly the same coloration as that given in my previous description. A drawing of the female medusa is given in Fig.

Experiments have been carried out with 203Hg-labelled n-amylmercuric chloride (n-C5H11HgCl) and mercuric chloride (HgCl2) to study the modes of action of these compounds as poisons to some crustaceans.

Differences between the susceptibilities of Artemia salina and Elminius modestus to the poisons do not reflect differences between the quantities of these compounds which the animals can tolerate in their tissues, but are directly related to the rates at which the poisons are accumulated. Thus, experiments with either species have shown that Hg is taken up at approximately the same rate from equitoxic solutions of the two poisons; and the rates at which Hg is accumulated by the two species from equitoxic solutions of either poison are of the same order.

Experiments with reduced glutathione have given results consistent with the view that most of the Hg taken up by either species penetrates into the tissues of the test animals and does not act simply by becoming attached to their surfaces.

Direct evidence of the penetration of Hg compounds into a crustacean has been obtained from experiments with Leander serratus. Considerable amounts of Hg have been detected in the antennary glands.

Cochlodesma praetenue is well adapted for a sedentary life in sheltered conditions in soft substrata at low-water mark to a depth of 60 fathoms.

The habits, morphology and ciliary feeding and cleansing mechanisms are described and compared with those of members of the related families Thraciidae, Pandoridae and Lyonsiidae.

The complex ligament is described. The mantle edges are extensively fused. The detailed structure of the siphons is described and related to their function of laying down mucus-lined inhalant and exhalant tubes.

The morphology and ciliary currents of the stomach show modifications similar to those previously described for Pandora. These modifications involve the extent of the major typhlosole and the replacement of an intestinal groove by lateral rejection grooves.

Analysis of three large samples shows that Cochlodesma from the Northumberland coast live for a maximum of 5 years. These animals become mature in their third year, spawning in early November.

Eudactylina rachelae n.sp. is described and figured. This copepod was found among the gill filaments of Torpedo nobiliana Bonaparte caught off Plymouth in July 1957.

An account is given of some features of the organization of the endostyle of Amphioxus, with particular reference to the distribution of sites of mucus secretion as indicated by positive responses to tests for acid mucopolysaccharides. Autoradiography shows that the centre of distribution of organically-bound iodine is associated with the tips of the mucus-secreting cells of zone 5, and not with the glandular tracts. Mucus secretion also occurs elsewhere in the endostyle (although not in the dorsal glandular tracts), but as it is not associated with any accumulation of bound iodine it is concluded that the binding in zone 5 is a specialized property of the cells of that particular zone. The results are discussed in the light of recent work on the protochordates and the ammocoete larva, and it is concluded that in Amphioxus, as in the Tunicata, there is reason for supposing that the iodination process is a biochemical specialization and that its product must therefore be of some physiological significance to the organism. Attention is also drawn to the evolutionary interest of the association of iodine-binding with a mucin rather than with a glycoprotein.

A general formula has been derived for the quantitative treatment of systems involving a number of interdependent equilibria. The formula has been applied specifically to the equilibria set up between metallic cations and their chelates when EDTA is added to sea water. This system involves competition for the fully dissociated quadrivalent anion of EDTA (the principal ion of EDTA which forms complexes) by the metallic cations and by the hydrogenions present. The equilibrium concentration of a metallic cation in any particular case will depend upon the equilibrium concentration of the quadrivalent anion of EDTA, in the sense that the higher the concentration of this ion the lower will be the concentration of the metallic cation. The general formula allows the calculation of the equilibrium concentration of the quadrivalent EDTA anion, and from this the concentrations at equilibrium of each metallic cation can be readily found.

The nematode Halenchus fucicola (de Man), causing galls on the thallus of the sea weed yAscophyllum nodosum, has been found in the Plymouth area (Wembury Bay) and at Croyde Bay on the north Devon coast, and a redescription of the worm is given. A new species of Halenchus (H. dumnonicus) causing similar growths on the sea weeds Fucus vesiculosus and F. serratus is described. This latter form is also found at Wembury Bay; at Looe, Cornwall, and at Lyme Regis, Dorset.

The English Channel may conveniently be divided into a western basin and an eastern basin separated by a line drawn approximately between the Cherbourg peninsula and the Isle of Wight. In these basins, the environmental factors are very different. Thus the water of the western basin is on average warmer and slightly more saline than that of the eastern basin and its temperature variation is less extreme. The French side of the Channel is warmer than the English coast only in the western basin. The tidal oscillations in the two basins are out of phase with each other and the strongest tidal currents occur where the two basins join. The main residual flow is up-Channel with minor coastal eddies.

The shores at the western end of the Channel are generally rocky, they are close to deep water, and so are exposed to frequent heavy swells. The shores of the eastern basin are generally erodible, and accumulations of sand and shingle tend to reduce the force of the waves. The water of the eastern basin generally contains more suspended matter and the shores are usually scoured by sand and shingle.

The distribution of the following animals is given in some detail and compared with earlier records: Ammonia sulcata, Actinia equina, Chthamalus stellatus, Balanus balanoides, B. perforatus, B. crenatus, B. improvisus, Elminius modestus, Verruca stroemia, Hemioniscus balani, Patella vulgata, P. depressa, P. aspera, Monodonta lineata, Gibbula umbilicalis, G. pennanti, G. cineraria, Littorina saxatilis, L. littoralis, L. littorea, L. neritoides, Paracentrotus lividus. The distribution of certain other species is also discussed: Balanus balanus, Haliotis tuberculata, Gibbula magus and Calliostoma zizyphinum.

The description of a new species of the genus Chrysochromulina, C. chiton, includes for the first time some evidence from the electron microscopy of sections in addition to the techniques previously used. Important diagnostic characters are the exceptionally large scales, which are shown to be of two kinds, the larger being saucer-shaped, and the smaller plate-like with a narrow rim flexed towards the upper surface; the structure and arrangement of the two types of scale on the body are described. Anatomical facts are given for the first time for the internal structure of the haptonema; in this species this organ consists of three concentric membranes surrounding a ring of seven fibres or tubes, the centre of the haptonema being hollow; this combination of characters distinguishes the organ fundamentally from a flagellum. Microanatomical facts are also given for the following major cell organs: the nucleus, the chromatophores including the pyrenoids, mitochondria, putative golgi material, muciferous bodies, the flagellar bases (preliminary observations only). Other distinguishable cytoplasmic components include the surface membrane, unsaturated fat bodies, vesicles of various kinds and granular protoplasm in the interstices.

On the flat shore at Whitstable the population of common winkles is distributed appreciably at random over a variety of substrata ranging from wooden groynes, through shingle to muddy sand, between tidal levels corresponding to H.W.N.-E.L.W.S. but with a maximum density near M.T.L., although aggregations tend to occur in wetter situations and where planking joins vertical groyne posts.

Observations on winkles marked with a dab of paint of distinctive colour show that they tend to remain in approximately the same position for many weeks.

For most of each tidal period winkles remain settled in situations such as stones or groynes, which provide good holding ground, but as the tide recedes or the incoming tide reaches them, they become activated to crawl, feeding meanwhile. These feeding migrations are recorded in the sand by roughly U-shaped tracks and can be seen under favourable circumstances as similar tracks in the vertical plane for winkles on groynes. By such excursions the animals are enabled to move, feed and return to approximately the place from which they started and this serves to explain how they maintain their station on the shore.

When settled on vertical surfaces, winkles always orientate with the head uppermost, when the foot may be withdrawn and the animal become attached by a film of dried mucus.

When crawling the eyes are exposed and the tentacles bend to test the substratum, but only that part of the tentacle distal to the eye bends so that the optical axis of the eye maintains a constant angle to the body axis.

Winkles dwelling on horizontal surfaces orientate by means of a lightcompass reaction. As the tide recedes, most of the tracks in the sand are towards the sun but after a time each animal reverses its direction of crawling, so tracing out a roughly U-shaped path which leads it back, approximately, to its starting-point.

When kept in an aquarium winkles tend to settle on the sides above the waterline and to become inactive. When stimulated, as by immersion, they crawl downwards, then horizontally and then upwards before settling above the waterline.

Winkles collected from horizontal surfaces at first show no tendency to climb vertical surfaces in an aquarium. After a period which varies from a few hours up to 10 days they do climb the sides of the tank. Animals collected from vertical surfaces climb the sides of the aquarium at their first opportunity and then settle. It can be concluded that winkles have an inherent tendency to climb and settle in the head-up position on vertical or steeply sloping surfaces but that if this opportunity is denied them they become habituated to horizontal surfaces.

The minimum angle to which winkles can react by gravitational responses is of the order of 10–20 degrees.

In an aquarium starved winkles prolong their excursions below water when presented with suitable food but fully fed animals respond less strongly to the stimulus of immersion.

Dark-adapted winkles from horizontal surfaces are at first positively phototactic, but after a time varying from 15 to 20 min, they become negatively phototactic. Tested with the ‘two-light’ experiment most animals disregard the second light (telotaxis).