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.

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.

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 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.

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.

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.

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).

The monogenean gill parasites from Scyliorhinus canicula and S. stellaris at Plymouth have been found to be identical; their proper taxonomic designation is Hexabothrium appendiculatum (Kuhn, 1829) Nordmann, 1832. H. canicula (Cerfontaine, 1899) Price, 1942 is a synonym of H. appendiculatum.

The hexabothriid collected from Raia clavata at Plymouth has been identified as Rajonchocotyle emarginata (Olsson, 1876) Sproston, 1946, and R. clavata Bracey (in Sproston, 1946) has been shown to be synonymous with it.

In Myxicola the rapid muscular response produced by direct stimulation of the nerve cord with a single shock is usually large and obeys a simple ‘all-or-nothing’ relationship to the intensity of stimulation. A single shock of sufficient strength evokes a single giant fibre impulse which produces an extensive contraction of the longitudinal muscle.

The magnitude of the summated contraction obtained by repetitive stimulation of the nerve cord is found to depend on the number and frequency of the shocks, thus providing the animal with a mechanism by which, theoretically, it could grade its escape response.

A comparative study of the following luminous copepods was undertaken: Metridia lucens, M. longa, M. princeps, Pleuromamma robusta, P. xiphias, Heterorhabdus norvegicus, H. robustus, Heterostylites longicornis, Lucicutia grandis, Hemirhabdus grimaldii, Disseta palumboi, Euaugaptilus magnus and Centraugaptilus horridus. Flashes produced by electrical stimulation (a.c. or condenser shocks) and mechanical stimulation were recorded photoelectrically. Flashes lasted from 2 to 37 sec. Latencies of some species (Metridiidae), following electrical stimulation, were very short, 7–9 msec. Intensities ranged from 0·02 × 10–5 to 14·4 × 10–5μW/s cm2 of receptor surface at 15 cm distance (0.0045 × 10–2 to 3·24 × 10–2μW/Cm2 at 1 cm) (10–20°C). Luminous glands of Metridiidae, Lucicutiidae and Augaptilidae are autofluorescent; the location of the luminous glands in these families and in Heterorhabdidae is described. Two kinds of glandular cells (types 1 and 2) occur in the luminescent areas. The cells are large saccular structures containing granular or homogeneous material, and are distinguished by staining peculiarities. Cell types 1 and 2 open through common pores, and may be the source of luminous reactants. Some measurements of luminescence in other pelagic animals are presented, for comparison with copepods, viz. Aequorea macrodactyla, Aeginura grimaldii (Hydromedusae), Periphylla periphylla (Scyphomedusa), Meganyctiphanes norvegica and Acanthephyra pelagica (Crustacea), Myctophum punctatum (Teleostei). Our present knowledge regarding luminescence among copepods is reviewed.

A species of Chrysochromulina is described which habitually produces four different types of scale on one and the same cell. Scales are more opaque to electrons than in other recorded species of the genus and it has consequently been possible to trace something of their mode of production. They develop within vesicles inside the body and are subsequently deposited on the cell surface. The vesicles responsible are in a compact group beside the Golgi body and below the flagellar bases. Scale-production is at a maximum in the afternoon and greatly reduced or discontinued at night. A marked diurnal rhythm also affects other cell components, mitotic phases being abundant at 4.30 a.m. Some changes occurring in the Golgi body are described and discussed in a preliminary way.

Low concentrations of various carcinogenic polycyclic aromatic hydrocarbons cause a considerable increase in cell production when applied to sporelings of certain marine red algae.

Whereas low concentrations of carcinogenic derivatives of benzanthracene stimulate cell production, similar concentrations of structurally related non-carcinogens inhibit it.

The applicability of the method as a rapid screening test for carcinogens is discussed.

Gastrocotyle trachuri and Pseudaxine trachuri infect young Trachurus trachurus at Plymouth as soon as the 3- or 4-month-old adolescent fishes descend to the sea bottom in October. The parasites normally mature in 3 or 4 months, but, exceptionally, in about 1 month, and the life-span is normally no longer than 1 year. Trachurus specimens at the beginning of their second year pick up a largely new infection of parasites.

G. trachuri and P. trachuri are much less frequent on 2- and 3-year-old specimens of Trachurus and probably occur only very rarely on still older fishes, the limiting factor being not an age-immunity but a post-spawning migration of the host from the concentration of free-living infective stages of the parasites in coastal waters.

The parasites have adapted themselves to a seasonal change in the feeding habits of Trachurus by ceasing to produce larvae in anticipation of the summer disappearance of scad from the sea bottom in pursuit of pelagic food-organisms.

Spirorbis corallinae sp.nov. is very similar to S. borealis but can be distinguished by its orange colour, small size, bifid opercular talon and particularly by the fact that the larvae choose to settle on Corallina officinalis rather than on Fucus serratus.

Other species dealt with, in a key to identification and notes on distribution, are S. granulatus, S. malardi, S. pagenstecheri, S. rupestris, S. spirillum and S. tridentatus.

In a series of experiments to investigate feeding and excretion in bivalves, Mya arenaria, Venus striatula, Ostrea edulis and Cuspidaria cuspidata were fed with suspensions of Phaeodactylum labelled with 32P. Although there is considerable variation in the filtering rates, specimens of O. edulis were found to have an average rate of 6·6 ml./h/mg dry body tissue. This figure is more than six times greater than that recorded for M. arenaria and V. striatula. No filtration was recorded in the carnivore C. cuspidata.

Laboratory experiments on feeding and respiration were carried out with the copepod Temora longicornis in the Clyde sea-area. In feeding experiments, a method using radiophosphorus as a tracer was employed. The filtering rate was very variable and is probably related to size. There seemed to be a seasonal variation in filtering rates. During the summer of 1961 weekly water samples were taken for estimation of the particulate carbohydrate in the sea. There was always enough food present for Temora. Respiration was measured by using a modified Winkler method. Oxygen consumption was related to surface area, and corrections in respiratory rates were made for the size differences in the animals used. Respiratory rates were very high at the beginning of an experiment, but after a sharp fall the rate became steady in about 30 h. An indication of seasonal variation in oxygen uptake was found.

Spirorbis rupestris sp.nov. has a sinistrally coiled, unridged tube and is distinguished from S. borealis Daudin only by colour, small morphological details and striking differences in larval behaviour. Though the larvae are capable of swimming, they do not usually do so, but crawl about and soon attach themselves to rock surfaces near the tubes of their parents, particularly when stimulated by the presence of the coralline alga Lithophyllum incrustans. They will not settle on Fucus serratus.

S. rupestris is found typically on rock surfaces in well-illuminated places throughout the lower half of the shore, generally associated with Lithophyllum. It is abundant on the shores of south-west Britain, except where there is scouring by wave-borne particles.

Six species of geophilomorph centipede are reported from the littoral zone in the Plymouth area, and in two cases, where they differ from previous descriptions, the significance of these differences is discussed. It is suggested that the various British and French populations of Geophilus algarum and Geophilus fucorum may be subspecies of one polytypic species.

It is shown that Strigamia maritima and Hydroschendyla submarina differ in the way in which they have adapted to life on the shore. The former lays permeable eggs and migrates out of the littoral zone to lay them and to moult, the latter lays impermeable eggs and moults in the intertidal zone. Information on the prey of S. maritima at Plymouth is given.

The variations between some populations of littoral centipedes is discussed and possible reasons for the high density of populations of S. maritima and H. submarina are given.

In freshly collected Naesa bidentata there exists a clear dependence of respiration rate, measured in sea water, on the tidal cycle, with the maximum occurring at high tide, the minimum at low tide. In specimens that had spent 1–2 days in the laboratory the tidal rhythmicity is less pronounced due to a lowering of the Qo2-values at high tide and at the beginning of experiments. This is interpreted as reflecting differences in nutrition between freshly collected and laboratory specimens.

The results of a comparative study of the breeding biology of the Manx pectinids with special reference to Chlamys varia, C. distorta, C. tigerina, C. striata and C. furtiva are presented.

It is shown that C. varia and C. distorta are protandric hermaphrodites with separate sexual phases similar to those of oysters, and evidence is presented on the possibility of sex reversal. The other species, C. tigerina, C. striata and C. furtiva, are truly dioecious, possessing at no stage germ cells of both sexes in the same gonad and as most individuals produce only one brood, the possibility of sex reversal is excluded.

C. distorta has two large-scale or peak spawning periods, once in summer and for the second time in autumn, although some spawning occurs as a rule in most months of the year. The breeding behaviour of this species is intermittent and therefore the breeding period is prolonged.

C. varia has two mass spawnings in a year, once in June and for the second time during September and October and the breeding period is not markedly different from that observed in French waters. Spawning is usually completed within a short period. C. tigerina and C. striata spawn only once annually in June and August respectively and most individuals have only one breeding cycle during their life time. C. furtiva however, may have two spawnings in a year, but the material available was inadequate to confirm this.