The results of analysis of sea water samples from the International Hydrographic Station E1 (500 02' N., 40 22' W.) are given in graphical form and as integral mean values for the water column of 70 m. Winter maximum values (in January) of 044/xg atom phosphate P/l. and 0-53^g atom ' T o t a l ' P/L, with 315/xg atom Si/1, were found. The phosphate and total phosphorus concentrations were unusually low. The spring decreases were 0-21/xg atom P/l. and 272 fig atom Si/1.

This paper lists over 100 species, mostly new records for Britain, found in the interstices of sand and shell gravel from North Wales beaches. The distribution of these species, other than the Kalyptorhynchia (Turbellaria) and the Gastrotricha, is given. The distribution of this fauna in relation to the substrate is discussed and species typical of fine-, medium- and coarse-particled substrates are listed.

The purpose of this paper is to assess the grazing capacity of Calanus finmar-chicus (Gunner.) in terms of the quantity of food eaten in the sea. The part played in the growth of the animal by the quantity eaten will only be briefly discussed. The parts played by nutrient lack, sinking and diffusion on the algal productive rates will also be discussed, leading to the conclusion that grazing mortality is the most effective controlling agent on algal production.

A subsidiary purpose of this paper is to relate changes in the weight of Calanus finmarchicus to changes in food consumed and to changes in water temperature. Measurements of C. finmarchicus have been made by a number of workers (Adler & Jespersen, 1920; Russell, 1928; Marshall, 1933; Stormer, 1929; Bogorov, 1934; Jespersen, 1939; Clarke & Zinn, 1937). It will be shown that in the North Sea, in spring, the greatest changes in weight are most readily related to changes in quantities of food consumed.

An account is given of the populations of P. montagui occurring off the Northumberland coast at depths ranging from 20 to 50 fm. Sampling, which extended from 1954 to 1961, shows that the population in 20–30 fm is composed predominantly of o-group males and females and smaller numbers of 1-group females while that in 50 fm is composed predominantly of 1 and 2 group males and females. This difference can be explained in terms of sex change and migration.

Eggs laid in the period from the last week in November to the first week in January hatch by the end of April. Growth of the new year-group is so rapid that they mature in time for the next breeding season. Egg numbers vary from 200 to 3000.

It can be calculated that the number of larvae hatched out inshore exceeds that offshore by 15 times, but many of the larvae produced by the deep-water.

The compound eye of the lobster H. vulgaris has a single lobe; its ommatidia are uniform except in length. Each ommatidium consists of a corneal facet, two corneagenous cells, four cone cells, a four-part crystalline cone, an elongate cone stalk, seven retinular cells and a four-part rhabdom. Growth between the zoaeal and adult stages is primarily a lengthening of the cone stalk.

The part played by nutrient salts in the study of marine productivity is well known. When this series of production cruises was being planned, it was decided to take observations of the quantities of different nutrients in the sea. The cruises were closely spaced in time in order to provide an opportunity for examining the fairly rapid changes in nutrient content in relation to algal numbers. Nutrient observations were not made at such frequent intervals of time, because the spectrophotometer could not be used from R.V. ‘Platessa’. On ‘Sir Lancelot’ it was found that the spectrophotometer could be used adequately only when the ship was steaming before the wind and constituted a stable platform; this limit, however, reduced the opportunities for sampling nutrients in the desired positions.

In the investigation described in this paper, respiration, resistance to desiccation and feeding behaviour of .the mid- to upper-tidal isopod Campecopea hirsuta was studied and compared with the analogous parameters of behaviour in the lower intertidal species Naesa bidentata

C. hirsuta occurs in the middle part of the shore where it can be found within empty shells of Chthamalus. Its preferred habitat, however, is the lichen Lichina pygmaea the vertical distribution of which extends from OD to MHWS.

Campecopea hirsuta feeds on the blue-green algae that make up the outer layer of the lichen L. pygmaea. When continuously submerged the isopod feeds in bursts, the timing of which is different in different specimens. This mode of feeding under experimental conditions is taken as reflecting the rhythmic way of life of this species in its natural environment but it seems to be controlled by endogenous factors. Naesa bidentata, on the other hand, does not display such endogenous rhythms in its feeding behaviour.

Thirteen cruises were made between mid-March and early June in 1954 off the coasts of southern Scotland and north-east England. It is likely that a Calanus patch was followed continuously during this period merely by observing the abundance of Calanus in and out the patch at very short time intervals (5–8 days between the mid-points of the cruises). Fig. 3 in Cushing & Tungate (1963) shows the distribution of Calanus copepoditestages during the period, which is the sort of picture expected if the same population were being sampled during the period. Application of the Joseph & Sendner (1958) equation suggested that the reduction of density due to diffusion was likely to be very low.

In mid-February 1963, a survey of sea temperatures in the western English Channel was made by means of a thermistor towed continuously behind the ship, also by water-bottle samples in a limited area between Plymouth and the Lizard. Evidence is given that surface temperatures, as measured by the thermistor, were representative of the whole water column. Sea temperature records from Torquay indicate that at this time temperatures were near their minimum for this exceptionally cold winter; at Plymouth where sea temperatures are usually more erratic because of estuarine influences the minimum had already been passed. A comparison with data for previous years at Plymouth shows that during January, February and March mean temperatures were lower than in any corresponding month since records were started in 1898.

Two species of wrasse, Ctenolabrus rupestris (L.) and Crenilabrus melops (L.) were experimentally infected with the digenean Proctoeces subtenuis (Linton) collected from Scrobicularia plana (da Costa). The fishes were killed 1-24 days after infection, and the parasite population of their guts examined. About 20 % of the introduced parasites survived for 2-3 days, but the degree of infection decreased with time, the smallest specimens surviving longest. No significant differences were found between parasites from invertebrate and experimental vertebrate hosts.

P. major Yamaguti, 1934, and P. insolitus (Nicoll, 1915) are declared synonymous with P. subtenuis (Linton, 1907

The bearing of these results on the life cycle of P. subtenuis is discussed

It has been observed that the pH in the different parts of the alimentary canal of Corophium is nearer neutrality; while the medium in the ventral hepatopancreatic caeca is more acidic, being in the neighbourhood of 6.2.

Investigations on the qualitative estimation of enzymes indicate that none of the enzymes are secreted by the gut proper. However, the ventral caeca only secrete many of the carbohydrate splitting enzymes; proteases and lipase are also secreted by the caecal cells of Corophium

It has also been estimated that the optimum pH for the activity of the caecal amylase lies in the neighbourhood of 5.8.

The fecundity of Clyde plaice, which has been studied from 1956 to 1961, has not been found to change as the breeding season approaches. However, there was a marked fecundity change from about 137 thousand eggs to around 161 thousand after 1957. The fecundity of all age groups increased and this appears to be associated with the fishing intensity and so the population density. Heavy fishing leads to fewer fish with the same food supply which in turn allows higher fecundity. The changes in fecundity therefore seem to be part of a density dependent population regulating mechanism.

A re-investigation of fresh material makes it necessary to create the new genus Thalassodrilus for T. prostatus (Knollner). Careful adherence to generic and specific criteria as detailed leads to the recognition of nineteen brackish-water and marine Tubificidae, and some dubious entities are also listed.

A method of determining the age of Laminaria hyperborea by examination of a longitudinal median section of the lower stipe and holdfast was found to be reliable for at least the first 4 years.

Variations in the breeding habits of cirripedes are discussed.

The effect of temperature and light during various stages of gonad development has been determined for B. balanoides.

Constant illumination inhibits breeding, the inhibition relating to the later stages of gonad development.

There is a critical temperature above which breeding will not take place, the level of which may possibly be raised by decreased periods of illumination. A period of 4–6 weeks at less than 12 h of light per day and below the critical temperature is required for maturation of the gametes. It is difficult to advance the date at which egg-masses are laid down by more than a few weeks.

The results are discussed in relation to the animal's ecology. There is a very close adaptation to boreo-arctic conditions; the north-south gradient in the time at which the eggs are fertilized is related to the temperature gradient but the constancy from year to year of this date in any one locality under the same micro-environment cannot be explained on the basis of temperatures. Light periodicity is probably involved.

The fecundity of Clyde witches was estimated from 1958 to 1962, and has been found to vary from over 49,000 eggs for a 26·8 cm fish to more than 599,000 in a 42 cm witch. Annual variations in the fecundity were found but there are not sufficient data to relate the changes to the population density as can be done with plaice. It appears that Clyde witches may grow faster, and they certainly attain a larger size than those in the Irish sea.

Photographic recording at hourly intervals of a group of animals contained in a small tank kept in continuous darkness has revealed a 24 h cycle of locomotor activity in Daphnia magna and in Calanus helgolandic

A change in periodicity of the rhythm in Daphnia kept under continuous illumination suggests that the cycle is not determined by external stimuli

The phasing of the cycle differs in the two animals, but in both there is an increase in activity during the hours of darkness.

In Calanus and possibly also in Daphnia, the cycle of activity is absent in the winter months.

Previous work on the biology and distribution of Calocaris is discussed briefly. The distribution in Northumberland waters is considered in relation to depth and bottom sediment.

Quantitative monthly samples show that population numbers remain very stable throughout the year. A well marked egg-laying period occurs in January-February when relatively few eggs (average 38) are attached to the pleopods. Eggs are carried for 8–9 months and hatch in September-October. By a combination of size-frequency distribution and gonad-developmnt classification the age-groups in the population are interpreted. After passing through a phase of testes development and spermatophore formation individuals lay their first batch of eggs at the end of the 5th year. The ovaries regenerate over a 2-year period and a second egg-laying takes place at the end of the 7th year with a possible third at the end of the 9th year.

The incidence of soft individuals in the samples together with observed changes in the coverage with epifaunistic growths indicate that after entering the 5th year a single annual moult cycle begins with a slowing down in growth rate.

Population numbers, fecundity and larval survival are discussed. Both the survival curve and the apparent lack of serious predation suggest that the population reaches senescence

Synthetic analogues of natural metabolites (antimetabolites) have been used to assess the sensitivity to inhibition of marine unicellular algae in laboratory cultures and also of more open-sea species grown in mixed culture in nutrient enriched sea waters. Different species show a different pattern of response to a range of antimetabolites. The presence of vitamins and metabolites in the medium influences inhibition of a species by an antimetabolite. The extent by which various sea waters influence inhibition is perhaps capable of development as a measure of the natural metabolites present. Species which are related or which occur together in the sea at the same time of year tend to show similar patterns of response. It is suggested that there may be a connexion between the susceptibility of species to antimetabolites and phytoplankton ‘succession’ in the sea.

Blood from Arenicola marina has been shown to contain an active catalyst of sulphide oxidation. This activity is associated with the respiratory pigments. Purified native haemoglobin and oxyhaemoglobin from this animal have similar activity in this respect to the analogous mammalian respiratory pigments and to mammalian hemiglobin. The oxidation product of Arenicola haemoglobin (the brown pigment) which is formed under conditions which might be expected to produce a hemiglobin is, in contrast, a very active catalyst of sulphide oxidation.