Cerithiopsis tubercularis and Triphora perversa feed on siliceous sponges: a long proboscis is thrust through an osculum of the sponge, or into breaks in the surface, to reach the softer parts. These are loosened by jaws, entangled in saliva and swept into the buccal cavity by the radula.

The formation of a long introvert, which must be withdrawn through the narrow space in the nerve ring and narrow enough to go through an osculum, has brought about (i) a lengthening of the mid-oesophagus in Cerithiopsis, with a narrowing of its diameter, and a spreading of the oesophageal glands along its length, (ii) in Triphora, a reduction of the ventral glandular part of the mid-oesophagus, its stripping from the food channel and a displacement of the salivary ducts so that they open into the glandular part of the oesophagus. In Triphora there is a dorsal gland of unknown function on the posterior oesophagus.

The stomach in both species is a simple ciliated sac: the oesophagus opens anteriorly and ventrally, and the intestine originates above this opening; there are two ducts from the digestive gland.

The pallial region of the male and female genital duct is open; and there is no penis. It is suggested that the open condition of the duct and the absence of a penis in the mesogastropods is correlated with a long, narrow mantle cavity which contains a relatively large ctenidium.

A review is given of the results obtained from upwards of 600 days of current measuring at the Seven Stones lightvessel during 1939–41. From the plotted observations, an attempt is made to deduce the association between the total daily water movement, irrespective of direction, the residual daily water movement or current, and the mean local residual wind.

The average residual water movement over the whole period was 2½ m.p.d. towards east-south-east. Statements made by earlier authors regarding the water circulation in adjacent areas are examined, and reconciliations are suggested where they seem to conflict with this finding.

An endeavour is made to correlate the wind and water movement mathematically.

The pigments of pure cultures of algae, of known number per volume, have been extracted with aqueous acetone after separation by filtration. The extracts were compared in a Kober colorimeter with standard solutions of a preparation of bought chlorophyll. The number required to give 1 mg. of chlorophyll was thus determined.

The algae studied included: Chlorophyceae, two species of Chlamydomonas and one Chlorella not yet described; Chrysophyceae, Dicrateria inornata Parke; Bacillariophyceae, Coscinodiscus centralis Ehr., Thalassiosira gravida Cleve and Nitzschia closterium (Ehr.) W.Sm. forma minutissima; Cryptophyceae, Hemiselmis rufescens Parke; Dinophyceae, Gymnodinium sp. The numbers per milligram of chlorophyll varied from 74 × 103 for Coscinodiscus to over 3200 × 106 for Hemiselmis rufescens. Of the nine cultures, six were between 50 and 750 × 106. The volume of the cell is the decisive factor in the milligram count.

The parasitic astomatous holotrich ciliate, Orchitophrya stellarum Cépède, has been found in the testes of starfishes (Asterias rubens) in the Plymouth area. It was found only in starfishes from numerically rich and well-fed populations, which also showed large gonad growth. In such populations it occurred in up to 28% of the males during March-April 1947, and in lower percentages during the spring of the three following years. The parasite was never found in a geographically adjacent population containing smaller numbers of poorly fed starfishes. The parasite was found to be relatively more common in the testes of medium-sized starfishes than in those of large and small starfishes.

Presence of the parasite causes a complete breakdown of all the germinal tissue of the testes, so that most of the infected starfishes suffer complete castration. This involution of the testicular tissue has been studied, and photomicrographs are given which show a number of stages in the process.

The genital products of Saccoglossus horsti are discharged within the burrows and expelled after the tide has ebbed. They are not retained in the burrows for any length of time.

Fertilization occurs mainly in the overlying surface water, or during the flood.

An ‘epidemic’ spawning was observed on three occasions in the field.

A rise of temperature to about 160° C. is regarded as the essential factor primarily responsible for initiating the spawning.

The females were observed to spawn before the males. Some reciprocal inducement might have occurred.

The breeding season in the Solent area is mainly confined to the months of May, June and July, and is seemingly dependent on climatic and tidal conditions during these months.

The spawning behaviour of other species of the Enteropneusta is discussed.

The diagnostic characters of the British species of Ensis are described. The shell remains the primary means of identification, but additional characters in the soft parts are necessary for certain recognition. The three forms of Ensis described are considered to be valid species.

The variability in catch of a series of hauls with a V.D. trawl taken under, as far as possible, controlled working conditions has been determined.

For analysis the species were divided into ‘round’ fish and ‘flat’ fish together with Nephrops; for both groups the coefficient of variation varied from 40 to 85 %. Taking 75 % as a representative value, the 2σ fiducial limits are 30–300 % for a single species from a single haul of half an hour duration.

It has been found that the standard deviation is roughly proportional to the mean, and that the variance is greater than the mean and increases with the mean. This suggests aggregation of the population.

The species are considered over the whole sampling period (4 weeks). Except for haddocks and dogfish the ‘round’ fish constituted a constant population. Changes were found in the other groups and their origin is discussed.

Simple methods for recording the water currents, which many polychaetes drive through their tubes, are described. The circulation may be either open (the worm having access to large amounts of well-aerated sea water) or closed (in which case the worm can circulate a small volume only, and there is no oxygenacion or removal of excretory products).

When on open circulation, both Chaetopterus variopedatus and Nereis diversicolor often trace quite regularly cyclical patterns for hours at a stretch. Each species has several possible patterns, and may change from one to another without evident external cause. The tracings of each species differ from those of the other, and also from those of Arenicola marina, which were described elsewhere.

The respiratory rates of four species of planktonic copepods were measured. In two of the species measurements were made with two copepodite stages, and with adult male and female specimens.

The rate for Calanus finmarchicus Stage V at 17°C. was found to be 0·52 μl./cop./hr., a figure which agreed with previous measurements.

For all the species and stages studied the respiratory rate was found to be closely proportional to the length to the power of 2·2.

The relevance of such measurements to conditions in the sea is briefly discussed.

The filtering rate of four species of marine planktonic copepods was measured by estimating the rate at which they consumed cultures of Chlamydomonas.

The filtering rate was independent of the concentration of the food organism and it is concluded that the copepods were acting as filter feeders.

The filtering rates were much greater than those reported by Fuller & Clarke (1936) and Fuller (1937), but agreed with those reported by Harvey (1937).

Some evidence was obtained that grazing was restricted to some only of the 24 hr., most probably to the hours of darkness.

The filtering rates were approximately proportional to the square of the linear dimensions of the copepod.

The purely mechanical selection suggested by Fuller (1937) to account for differences in filtering rates obtained with different species of diatoms cannot account for all the differences which have been observed.

It is probable that the copepods could obtain sufficient particulate food in the sea by filtering a daily volume of water corresponding to the filtering rates found.

A study has been made of the food, population, and some aspects of the ecology of the common seal (Phoca vitulina L.) along the East Anglian coast.

Examination of stomach contents of 194 seals killed in the Wash in 1947 confirms earlier evidence that the species here feeds largely on whelks (Buccinum undatum). The food is estimated by weight as 92 % molluscs, 4 % fish and 4 % Crustacea. Young seals for 2–3 months after weaning feed almost exclusively on shrimps (Crangon vulgaris).

Data derived from six stomachs, together with verbal reports, suggest that seals on the open coast feed more exclusively on fish, chiefly pleuronectids. This agrees with the findings of other workers in Holland and Washington State, U.S.A., that fish are the primary food animals. It is therefore suggested that in the Wash, where suitable breeding sands are common, the seals have become adapted to feeding on a ‘second-class’ food in the absence of dense stocks of fish.

The production of chemicals from the brown seaweeds is one of the oldest branches of the chemical industry, having its origin as far back as 1720 when soda was first produced from kelp in France, and soon after taken up in Ireland, Scotland and Norway. Until the early nineteenth century this was the only source of this chemical on which the glass and soap industries were built up. When the cheap Leblanc soda later became competitive the industry was able ot switch to potash and iodine production, a demand for which had arisen about the same time. This industry reached sizeable proportion, as is evidenced by the fact that in 1820 more than 20,000 tons of kelp were produced in the Outer Hebrides, involving the collecting and burning of about a million tons of cast weed.