Cucutnaria elongata Düben & Koren, collected from the Northumberland coast in January 1968, was induced to spawn in the laboratory by raising the temperature. At spawning, the animal waved its pharyngeal bulb back and forth while a thin string of gametes was discharged. The freshly spawned eggs, surrounded by a jelly coat, were at the end of the second meiotic division and the size varies from 250 to 350 μ in diameter. Oocytes in the ovarian tubules can be grouped into three stages according to their size and other morphological features. Insemination of artificially recovered eggs resulted in only a very low frequency of abnormal development up to 8-cell stage. However, over 90% fertilization was achieved by insemination of the naturally shed eggs and the development was normal. The cleavage was holoblastic and radial type. The larva hatched at post blastula stage and swam freely with its animal pole upward. A doliolaria stage with four ciliary bands and pentactula stage with five primary tentacles subsequently developed. The planktonic life at temperature 9–11 °C ended on the ninth day after fertilization. Pentactula, up to 4 months old, live underneath the mud where they are deposit feeders. The primary tentacles bearing mucus glands in the form of papillae are important in both locomotion and feeding. An outline of chronology from fertilization up to 5 months old is presented.

Thin-layer chromatography on plates coated with silica gel and with sucroseglucose (1:1) has been used in the study of the pigments of twenty species of marine phytoplankton from four phyla. A number of apparently new xanthophylls have been found, including a fucoxanthin-like pigment which is the major xanthophyll in an unidentified coccoid alga (Plymouth no. 407).

The biology of the marine leech Oceanobdella blennii, ectoparasitic on the littoral fish Blennius pholis, was studied on the coast of North Wales from 1964 to 1966. Leeches first appeared on the fish in large numbers in December, but were less common in January. During February and March they became more abundant on individual fish and among the host population as a whole, but in April and May the leeches began to disappear and none was ever found from June to November.

The structure of the tentacular crown in a multitentaculate pogonophoran, Siphonobrachia ilyophora Nielsen, has been examined by light and electron microscopy. The fine structural organization of the tentacles is described and discussed in relation to the suggested functions for the tentacles in Pogonophora.

The biochemical constituents of mussels both infected and free from the copepod parasite Mytilicola intestinalis Steuer have been determined over a period of 2 years. All the constituents except moisture content (i.e. lipid, protein, carbohydrate and ash) were determined from dried mussel flesh, and all showed seasonal variation, the changes of which were correlated to the breeding cycle of the mussel.

The regulation of total algal numbers in the symbiosis involving Anemonia sulcata and a marine dinoflagellate has been investigated in a series of experiments designed to test the effects of starvation and/or darkness on the host and its alga. The gross effect of these conditions (either separately or in combination) is detectable as a generalized weight loss in the symbiotic system. An electronmicroscopical study has shown that this weight loss can be directly related to changes in the ultrastructural morphology of both Anemonia and its symbionts. The significance of these findings is discussed in relation to current knowledge of the nutritional aspects of algal—invertebrate symbiosis.

A study has been made of the relationship of Phaeodactylum tricornutum (Bohlin) to iron, manganese and zinc. Evidence is presented showing that, in batch culture, the three elements behave differently as regards their uptake into the cells, the amounts present in the cells and their distribution between cells during the growth of the culture. The implications of these differences are considered.

Pseudocalanus elongatus(Boeck) from Plymouth Station Ex was kept in reproducing culture for 6 months and approximately four generations. Cultured adult females were at least as large as wild females of the same species which have matured at a comparable temperature (15 °C) in nature. At 15 °C hatching time was 2—3 days, time to first copepodite was 18—20 days, and the time from egg to development of an egg-carrying female averaged 37 days.

The estuary of the Tamar has been surveyed from March to September 1968. Salinity distributions and variations have been measured with the object of providing a preliminary picture of the general circulation. Tidal flows appear to have most effect on water movement in the estuary.

The effects of oil-spill removers (‘detergents’) on a population of the dogwhelk Nucella lapillus have been studied at Porthleven in South Cornwall, where heavy oil pollution occurred following the ‘Torrey Canyon’ incident in March 1967. Nucella is one of the shore animals which are most resistant to ‘detergent’ treatment, but at Porthleven the species was wiped out in the harbour and the majority of animals were killed on the reef nearby.

The distribution of Laminaria ochroleuca along the south-west coast of England and the Isles of Stilly is brought up to date. The pattern of distribution is discussed with reference to certain factors controlling the ‘ performance’ and success of the species on the northernmost edge of its range. The performance of individuals of the species (measured as net stipe production) sampled from populations growing on the coast of south-west England is compared with populations from north-west Spain, where it is growing in the centre of its geographical range.

The degree of exposure to direct onshore wave action appears to govern the upper limit of its bathymetric range as well as its distribution along the south-west coast of England.

It was found possible to age this species using the method and precautions described by Kain for Laminaria hyperborea.

The stipe material sampled from the English populations had a higher ash content per gram dry weight and a higher calorific content per gram of organic material than that from the Spanish populations.

Individuals from the English population had a lower weight per unit length of stipe in all age-classes than those from Spain.

It is suggested that incident radiation may be a more important factor than temperature in controlling the northward limit of the species.

A similar inhibitor has been found in red mullet {Mullus surmuletus L.), megrim (Lepidorhombus whiff-iagonis Walbaum) and greater forkbeard (Urophycis blennoides Briinnich). The inhibitor is of a seasonal nature in these fish also and may be linked with the spawning cycle.

The responses to light and temperature variations of the gametophytes and early sporophytes of Laminaria hyperborean were compared in culture with those of its main competitors in Britain, namely L. digitata, L. saccharina and Saccorhiza polyschides. Some undeveloped gametophytes of all species are able to survive in the dark for at least 80 days.

The lesser argentine, Argentina sphyraena L., is a Mauretanian-Mediterranean-Boreal species extending from about 68° N. off the Norwegian coast to 25° N. off Spanish West Africa. It is most commonly caught on the offshore continental shelf in depths between 50 and 100 fm where average sea temperatures of 6° and 17°C are encountered at the northern and southern limits respectively of the species geographical range. Larger, older fish are taken in deeper water, and occurrences inshore and at depths less than 50 fm are usually associated with the presence of deep trenches over 50 fm.

Idotea metallica Bosc is a dark-brown or blue-black species, its colour being controlled largely by the degree of expansion of, and pigment concentration in, the dermal chromatophores. In addition, the iridophores produce the characteristic metallic sheen by Tyndall scattering.

The activity of lactate dehydrogenase was measured in the livers of 36 species of fish. These species could be divided into two groups, those with liver activities of more than 1000 mU/mg protein and those with activities of less than 100 mU/ mg protein. The lactate and pyruvate of samples of blood, muscle and liver from cod, plaice, bass and mackerel were determined. Samples were taken from ‘rested’ and trawled fish and from fish allowed to recover for 3 h after trawling. The rate of removal of lactate from the white muscle after capture in the trawl was not related to high blood and liver activities of lactate dehydrogenase. There was no relationship between the activities of nine of the glycolytic enzymes in the white muscle of cod and plaice and the liver lactate dehydrogenase activity. Little blood lactate appears to be taken up by the liver. It is concluded that the liver of cod, plaice and bass has a negligible role in metabolizing blood lactate.

The original descriptions of species of the genus Ptychodiscus are discussed. Recent material is examined both alive and preserved. It is concluded that the only valid species is Ptychodiscus noctiluca Stein. Ptychodiscus carinatus Kofoid, P. inflatus Pavillard and Diplocystis antarctica Cleve are all synonymous with this species.

The effects of salinity, light intensity, temperature and pH on the amounts of nitrogen fixed and liberated extracellularly by the marine blue-green alga Calothrix scopulorum (Weber et Mohr) Ag. ex Bornet et Flahault have been investigated.