Orton's account of ciliary mechanisms on the lophophore of Crania anomala (Müller) is confirmed. Observations on the natural orientation of the lophophore have modified his account of the filter-feeding water currents. As in other brachiopods the lophophore divides the mantle cavity into inhalant and exhalant chambers with separate apertures to the exterior. The inhalant chamber has two apertures, is ventral in position, and extends into the interior of the spiral brachia; the exhalant chamber is dorsal in position and has three apertures. The development of the lophophore in the later growth stages is described. Both in development and in the form and function of the organ in the adult, the lophophore of C. anomala closely resembles that of the articulate species Tegulorhynchia nigricans (Sowerby): it is suggested that this reflects an inherent limitation on the possible variety of lophophores in brachiopods.

Effects of water of reduced salinity on the vertical migration of the zooplankton of Southampton Water were investigated in the laboratory using the adults of six copepod species (Acartia tonsa, A. bifilosa, A. discaudata, A. clausi, Centropages hamatus, Temora longicornis) and the larvae of one decapod species (Porcellana longicornis). Additional observations were made on Centropages typicus adults taken off Plymouth.

Salinity discontinuity layers had a marked effect on the vertical migration of zooplankton. A single discontinuity layer formed by placing less dense diluted sea water over full strength sea water acted as a barrier to animals attempting to swim toward the surface of an experimental water column and no individuals were able to enter the zone of reduced salinity when an extreme dilution was used. Comparison of the behaviour of various species and of different sexes or developmental stages of a particular species suggests that vertical distribution was partly dependent on the salinity tolerances of individuals. Upward migration was also restricted by a vertical series of discontinuity layers.

The swimming activity of copepods was depressed in homogeneous water columns of reduced salinity. Activity depended both on the degree of dilution and on the period of immersion. There were indications that behaviour varied according to the salinity tolerances of the different species.

The ophiuroid, Ophiocomina nigra, is noted for its variability of colour, a phenomenon most pronounced where the species also has its greatest distribution in depth. Observations have been made on two geographically distinct populations, from the vicinities of Millport and Plymouth. The body colour of the observed animals ranges in a continuously graded series from black to orange-yellow. While both populations exhibit analogous variations, there is a distinct difference in the range and tone of coloration which each displays. It is suggested that this geographical difference is correlated in some degree with differences in colour tone of the substratum. It was observed that the incidence of light-coloured phases in each population increased with increasing depths, and some statistical evidence supports this conclusion. Thus, at least two factors, depth and substratum, may affect the distribution of colour variations in O. nigra

In addition to the variations in general body colour, there are two distinct colour patterns found on the disk. These are probably truly polymorphic and may be of cryptic value.

A scheme of colour classification is described which facilitates observations in the field and in the laboratory.

The ophiuroid, Ophiocomina nigra, displays a colour variation ranging from black to yellow-orange. The pigment responsible for the dark colours has been studied histochemically and by means of chemical techniques applied to extracts. The solubility, oxidation-reduction, fluorescence and other chemical properties of this pigment indicate that it is a true melanin. The visible colour of die melanin depends upon its oxidation state in the integument. Fully oxidized pigment is dark brown; partially reduced pigment is fawn coloured.

Material of Cricosphaera carterae was examined cytologically with the acetocarmine technique. Nuclear division is similar to that found in higher plants. Investigations showed there to be a chromosomal alternation of generations, which corresponds to the morphological alternation. The motile phase is diploid, 2n = 42 ± 2, and the non-motile phase is haploid, n = 21 ± 1.

A method is described for obtaining the venom from the dorsal fin of the lesser weever without harming the fish. It is suggested that the amount of venom normally injected into the wound by the weever when it stings is O-5-O-2 mg dry weight of venom. Some 60% of the dry weight of the venom appears to consist of toxic muco-substances, which have a neurotoxic effect, but are without toxic effect on the blood. In extracts this fraction may be separated into two albumins and an amino polysaccharide, though in the native venom these are probably associated into a single complex mucosubstance. When injected subcutaneously this fraction of the venom produces no local pain. The venom also contains about 1-20 jug/mg (dry-weight basis) of 5-hydroxytryptamine which appears to be the origin of the pain of the sting, together with some undetermined histamine releaser (not an indole) of low molecular weight. It is suggested that the chief role of the 5-hydroxytryptamine in the venom is to produce pain around the area of the inflicted wound.

The range of temperatures over which the cirri were active and the frequency of beating at different temperatures were measured in four species of barnacles collected on the southern and south-western coasts of France. The extremes of high temperature at which the animal remained irritable or could survive were assessed in these species and in a further group of species from Trinidad, West Indies.

The results are discussed in comparison with previous evidence for species of more northern distribution, and related to the geographical range of the species and the ecological niche occupied. For example, the brackish water species, Balanus eburneus and B. improvisus, have similar patterns of cirral activity, but the greater tolerance of high temperatures shown by the former is obviously connected with its more tropical distribution. Differences in temperature tolerances of varieties of JB. amphitrite from Europe and Trinidad, possibly related to differences in the tide levels at which they live, tend to reinforce their separation on morphological grounds. More pronounced differences between Chthamalus depressus and C. stellatus confirm the separation of these two species which were formerly regarded as varieties. The relatively lower rate of beating of C. depressus which is not found north of the Mediterranean and its greater tolerance of high temperatures compared with C. stellatus, may be related to its more southern distribution and its ability to live at very high levels on the shore. These two species and C. fragilis from Trinidad all show greater tolerance of high temperatures than the species of Balanus and Tetraclita, which are found at lower levels on the shore

It is concluded that in the North Atlantic area there may be only two main distributional groups of species of acorn barnacles, Arctic and Tropical, overlapping in the Temperate regions, with few or no intermediate forms, and that there is as yet no evidence for the existence of physiological races in these species.

The method, which is suitable for algae down to 2 μ in diameter, determines the weight of total fatty acids (however originally combined) and total unsaponifiable fat-soluble matter in fresh algal material containing 20–280 mg total dry matter. The chemical treatment is based on that of Belin (1926). Experience with variations of the method on several algal species is described. Preliminary Soxhlet extraction with 95% ethanol for 18 h removed virtually all the lipid from the algae, ready for purification and further analysis, in the cases of Chlorella marina, C. vulgaris and Scotiella sp. (Chlorophyceae), Tribonema aequale (Xanthophyceae), Isochrysis galbana (Chrysophyceae) and Phaeodactylum tricornutum (Bacillariophyceae). This extraction was not efficient, however, in the cases of two members of the Myxophyceae (Anabaena cylindrica and Microcoleus vaginatus) and one of the Rhodophyceae (Porphyridium cruentum). The fat metabolism of these two classes is known to differ from that of other classes, but a similar inefficiency in the case of Monodus subterraneus (Xanthophyceae) is unexplained. In such cases supplementary processes were necessary to achieve full extraction. The methods are described in detail.

The red to orange-yellow colours of the ophiuroid, Ophiocomina nigra, are due to carotenoid pigments contained in specialized lipocytes. These cells are dendritic, with their cell bodies located in the dermis below a melanocyte layer and with dendrites approaching, but not penetrating, the epidermis. The lipocytes are either yellow or orange-red.

Five principal pigments were detected in addition to two minor constituents, at least one of which may be an artifact. These major pigments are: β-carotene, an acid carotenoid similar to mytiloxanthin, and four xanthophylls of uncertain identity.

The perivisceral and ambulacral fluids of Asterias rubens have been shown to be not only isosmotic but isoionic with sea water, even if that medium is diluted by nearly half. However, there is a slight accumulation and regulation of calcium in the perivisceral fluid and to a much more marked extent, potassium in the water vascular system. The rapidity with which the potassium diffuses away when the ambulacral fluid is dialysed against sea water suggests that its presence in the water vascular system is due to an active accumulatory mechanism. This mechanism is capable of functioning when the animal encounters sea water of significantly reduced salinity, over the temperature range 0—20° C and extends throughout the season apparently uninfluenced by the breeding cycle or sex of the animal. Smaller animals tend to have a higher concentration of potassium in the water vascular system than do larger ones. Direct and indirect measurements of salt loss under various conditions, together with observations on the rate of lithium transfer, suggests that the integument is very permeable to many ions as well as to water. This supports the hypothesis that the ionic regulation observed results from an active process and not merely from an impermeability of the integument, although measurements with potassium itself have not yet been made.

The results of a short investigation of the population of ormers (Haliotis tuberculata) are described and discussed. The average number of ormers found by diving between 0–5 fm. below low tide was 2·4 per m2. The catches were measured, but no separation of year-groups was found.

The external and internal structure of the spines of Squalus acanthias are described. Internally the spines consist of a series of dentine cones laid down one within the other. This series is reflected in the external structure by bands of pigment associated with ridges of enamel. The latter are proved to be annual.

The use of the spines for age determination is discussed and the growth parameters and growth curves calculated. The results obtained differ from those of previous authors, whose work is critically discussed.

In ecological studies of benthonic organisms it is advisable to sample the water immediately above the sediment-water interface rather than centimetres or metres above the bottom. The standard oceanographic water samplers cannot be relied upon to sample at the required level so a new instrument was designed. The instrument here described is a strengthened and simplified version of that described for use in shallow waters (up to 4 m) by Murray (1963). It has been successfully used in waters of up to 60 m deep but should withstand depths of up to 180 m.

The accumulation of 137Cs from sea water has been examined in relation to potassium metabolism in the lobster Homarus vulgaris and in the prawn Palaemon serratus. In unfed animals 137Cs is taken up and lost far more slowly than 42K. Although all the inactive K in the animals can be exchanged with 42K, higher whole-animal concentration factors are reached for 137Cs (about eight for lobsters and twenty-five for prawns). This is because both species have higher plasma/medium ratios for 137Cs than K at equilibrium despite the selective excretion of 137Cs. Also, except for the hepatopancreas in lobsters and fed prawns, all soft tissues can probably attain higher tissue/plasma ratios for 137Cs than inactive K.

Uptake of both isotopes has also been studied in the freshwater crayfish Austropotamobius pallipes pallipes. In crayfish in o-i % sea water 137Cs is not concentrated to the same extent as K by whole animals (50-200 for 137Cs against about 4500 for K). Although the situation between plasma and tissues resembles that in the marine animals, 137Cs cannot be accumulated in the plasma to the same degree as K. Crayfish selectively excrete 137Cs in the urine relative to K at a lower concentration than in the plasma.

In the accumulation of 137Cs by all species, muscle is the principal limiting factor in uptake and loss, but with 42K the body surface becomes more limiting.

Experiments on the absorption of 137Cs from food in prawns and freshwater crayfish have been carried out. In prawns in a constant environment, feeding is probably less important than uptake over the body surface while in crayfish feeding is probably much more important.

Sporelings of the marine red alga Plumaria elegans, grown under continuous illumination from a fluorescent tube, show a maximum rate of cell production at a light energy flux of 10 ergs/sec/mm2 in the range 380—720 mμ. This amount of light energy is low, but compares closely with that illuminating Plumaria in its natural habitat at Wembury during the period of the year when the plant is producing spores.

Pelagic plaice larvae in the southern North Sea normally feed exclusively on the appendicularian Oikopleura dioica, and the size of prey eaten can be estimated from the Oikopleura faecal pellets found in the larval gut

Predator-prey size measurements show that smaller plaice larvae are restricted to smaller prey, and that, as larval growth proceeds, so their feeding versatility increases, to include all sizes of Oikopleura at a late pelagic stage of development. Competition for food will therefore be keenest in the early larval stages, when prey-size restriction prevails. This accords with Hjort's hypothesis regarding brood strengths.

As growth proceeds, so plaice larvae begin to discriminate for prey size. At the close of the pelagic phase, the degree of size selection is roughly equal to that of a 6o-mesh to i in. plankton net.

An undulating movement of the body was observed in Entobdella soleae, a monogenean found on the blind surface of a mud-dwelling flat-fish, Solea solea, at Plymouth. The movement is described and shown to have a breathing function, the rate of undulation increasing with decreasing oxygen content of the ambient sea water and vice versa.

The relationship between the movement and micro-habitat is discussed and the phenomenon is compared with breathing movements in other muddwelling animals.

A similar movement was noted in three other skin-parasitic monogeneans: Acanthocotyle sp. from Raia clavata, Pseudocotyle squatinae from Squatina squatina and Leptocotyle minor from Scyliorhinus canicula.

Records are given of Kinorhyncha from muds at 101–140 m depth off the Scottish east and west coasts. All three suborders of Kinorhyncha are represented, and one new species and two new larvae are described.

An analysis has been made of plaice fecundity at four localities in Norway. The fish tended to be larger than those used in other fecundity investigations, and the comparison between localities has been made by considering the average egg number expected in a 50 cm fish. In general the plaice off Norway had more eggs than in the North Sea or round the British Isles. At Arendal in the Skagerrak the fecundity was 355 thousand for 50 cm, which is lower than has been found in the Kattegat, but a little higher than I found at Bergen (317 thousand eggs). At Arendal and Bergen the fecundity was higher than has been found in the North Sea but lower than in localities farther north in Norway. In Trondheim Fjord the plaice fecundity was very high indeed. Among the eleven fish examined it varied from 673 thousand to nearly ½ million eggs, and for an average 50 cm plaice would be 819 thousand. The female fish on the coast outside the fjord were quite different and contained about half the number of eggs (407 thousand for 50 cm). These coast plaice were very similar to those caught in the vicinity of Tromso where a 50 cm fish would have about 400 thousand eggs.

Counting the numbers of phytoplankton organisms in water samples is time-consuming. A knowledge of the kind of organisms present and their relative numbers is essential, but it is useful to have in addition a measure of the quantity of organic substance present. A number of methods have been suggested for measuring the standing crop of phytoplankton and these have been summarized recently by Strickland (1960).