A population of the lamellibranch Tellina tenuis in the Exe estuary is shown to be uniformly distributed, indicating a significant degree of ‘over-dispersion’.

By plotting the position of each shell in squares of m.2 area it is shown that fewer individuals than would be expected occur less than 1 in. from their nearest neighbour, and none occurs closer than 0·6 in.

When the population density was artificially increased on the shore the same characteristic spacing was found at a moderate density, but not at a rather higher density.

It is suggested that spacing is correlated with the foraging activities of the inhalent siphon on the soil surface.

Very dense populations have been found by Stephen in other areas, indicating that the size of the ‘territory’ does not limit density. His results show no evidence of the same phenomena as observed in the Exe.

This preliminary list of some of the classes of the algae has been prepared, mainly for the use of British phycologists, to form a basis on which to work for the eventual compilation of a complete check and locality list of all species of British marine algae. The compiler would be grateful for all additions and corrections to this list, and for records of marine species from the algal classes not included in the present list.

The classes of algae treated in this list are the Chlorophyceae (53 gen., 156 spp.), Xanthophyceae (7 gen., 15 spp.), Chrysophyceae (15 gen., 22 spp.), Phaeophyceae (96 gen., 199 spp.), Rhodophyceae (126 gen., 324 spp.), and Cyanophyceae (39 gen., 125 spp.). The genera are listed alphabetically under the family and the species alphabetically under the genus. If a name has been changed from that given in Newton (1931), the name in Newton is added, in brackets, below. Names preceded by a question mark appear to need revision for nomenclatural or taxonomic reasons. Most of the so-called varieties listed are very probably merely habitat forms of the species, but further investigation is needed before new combinations are made for them. Notes are given at the end of each class, the number in brackets following a name in the list refers to these notes.

The compiler is grateful to Mr R. Ross and Miss Linda Newton, of the British Museum, and to Miss C. I. Dickinson, of the Herbarium, Kew, for their help over a number of problems.

In common with many teleosts, herring show marked ‘fast startle’ responses when subjected to sound stimuli from a vibrating source (Blaxter, Gray & Denton, 1981). These comprise a sharp C-shaped contortion of the body; the fish respond to transients of as little as half a cycle of sound with a latency of about 25 ms and the turn is usually away from the sound source. There is good evidence that the Mauthner cells are implicated in other species (see Eaton & Hackett, 1984) but this has not been established in the herring, although they are known to be present.

The results of the writer's investigations on the ciliary mechanisms on the gills of Mollusca and Amphioxus (1 and 2) gave rise to the suggestion that similar mechanisms might probably also occur in Brachiopods, for it is a well-known fact that Brachiopods—like some Molluscs and Amphioxus—feed on the smaller organisms which are to be found floating in the sea. Owing to the kindness of Dr. H. C. Williamson, of Aberdeen, I have been able to examine living Crania which were obtained by dredging in Loch Fyne, and living Terebratula have also been obtained from Naples. An investigation of the living gill-filaments—or lophophoral cirri, as they are frequently termed in this group—showed that the ciliary mechanisms on these filaments are essentially the same as those occurring on the gill-filaments of Amphioxus, Lamellibranchs, some Gastropods, and most Ascidians. As it was found that existing accounts of the mode of feeding in Brachiopods are vague and incomplete the following description of the process has been written.

The first known occurrence of a naturalized population of Manila clam (Tapes philippinarum) in UK waters is reported. Introduced into Poole Harbour for aquaculture in 1988; by 1994 local fishermen and wading birds began to exploit this northernmost naturalized population in Europe. The licensed fishery currently supports 31 local fishers, landing approximately 250 tn. of clams in 2002. The current distribution of the clam in Poole Harbour, the biology of this naturalized population and the ecological impact of its introduction and fishery, is described.

Members of the Haptophyta from British waters have been listed in a number of check-lists between 1953 and 1976 (Parke, 1953; Parke & Dixon, 1964, 1968, 1976), but there has been no attempt to draw the records together on a world-wide basis. However, a recent review of the classification system of the coccolithophorids included a check-list of all species thought to be extant from marine, coastal and freshwater habitats (Jordan & Kleijne, 1994). At the same time, two ambitious projects, the Encyclopaedia of Algal Genera (ed. B.C. Parker, in preparation) and the preparation of a CD-ROM retrieval system for information on algal and protist groups by the Expert-Centre for Taxonomic Identification (ETI), have required further collation of the available records (see Note 1), and, as a result, we have now extended the scheme of Jordan & Kleijne (1994) to include a global list of all extant haptophytes.

Records of the occurrence of postlarval stages of teleostean fishes in the plankton off Plymouth have been kept for a period of nearly 50 years. During that period noteworthy changes in the abundance of postlarvae have taken place. While in the 1920s postlarvae were very abundant in the plankton, in the 1930s they became much fewer at about the time when the herring fishery declined. Somewhere around 1965 another change took place and post-larvae became once more very abundant. There was also a marked increase in the quantity of macroplankton, which like the young fish had become much reduced in quantity in the 1930s (Russell et al. 1971).

The head of the sperm whale (Physeter macrocephalus L.), which is largely snout and the crest of the skull necessary to support it, may exceed a third of the total weight and a quarter of the length of the whale. This indicates the snout has an extremely important function but few theories regarding its function take into account the overall structure, whilst the detailed structure and proportions of the adult's snout have been almost totally neglected. Similarly, consideration of the thermal properties of the spermaceti oil, which is the most remarkable component and constitutes a large proportion of the head, have been neglected in studies of function.

In simple choice experiments Protodrilus symbioticus Giard, an interstitial archiannelid, was shown to prefer the sand from its habitat in the natural state to the same sand altered by various physical or chemical treatments. The attractiveness of a sand was measured as the ratio of the number of Protodrilus entering the experimentally treated sand to the number entering the natural sand in simple or multiple choice experiments.

The attractiveness of natural sand to P. symbioticus could be destroyed almost completely by acid cleaning, by heating in water above 50° C or by drying at any temperature.

Treating attractive sand with formalin or cetyltrimethylammonium bromide rendered it about half as attractive as before treatment. Heating natural sand in water to 40°C and keeping it in fresh water for 18 h had no effect on the attractiveness. Sands that have been made unattractive by acid cleaning or drying can be restored to an attractive state by soaking in sea water. Typically acidcleaned sands recovered up to half and dried sands almost the whole of the attractiveness.

Inoculation of naturally occurring sand bacteria to highly unattractive acid-cleaned sand restores the attractiveness completely. Autoclaved sand to which a culture of Phaeodactylum had been added was preferred to sand treated with cultures of Dunaniella and Chlorella. An ordinary culture of Phaeodactylum contaminated by bacteria restored the attractiveness to autoclaved sands more effectively than a bacteria-free culture.

Sands restored by inocula of natural sand bacteria, soil bacteria and Pseudomonas sp. were preferred to those treated with Corynebacterium erythogenes, Flavobacterium sp. and Serratia marinorubra and these were preferred to control sands kept in sterile sea water.

Adult males of Nereis virens (Sars) spawn while swarming in mid-water and show epitokous changes which include enlarged parapodia, natatory chaetae and histolysis of the body wall. Females spawn while in their burrows and do not show such changes. An artificial rise in temperature can induce premature spawning. Seminal fluid is ejected through pygidial pores, but no such pores occur in the female. Both lunar period and temperature rise seem to be involved in initiating spawning, which generally occurs in early May in the Thames populations. Gravid worms show a peculiar method of swimming in which the anterior region is held rigid. A pair of flagellar vanes and other features characterize the fine structure of the spermatozoon. The mature oocytes bear microvilli, and some express a jelly-like layer after fertilization which traps excess spermatozoa. Many unit-membraned vesicles, of uncertain function, occur in the periphery of the nucleus of the mature oocyte. At fertilization the acrosomal contents are discharged on to the surface of the oocyte. The structure and behaviour of the monotrochophore, trochophore and nectochaete larvae, and the details of the nature and rate of development of such structures as the parapodia, cirri, palps and jaws, differ in some ways from the known larval development of certain other nereids. A very brief planktonic phase occurs in larval life, and young worms migrate from the sublittoral to the littoral regions.

Growth laminations were first noted in squid statoliths by Clarke (1966), who suggested they might be useful for age determination. Spratt (1978) presented a detailed age analysis of Loligo opalescens Berry, 1911, arguing that some rings in the cephalopod statolith were deposited daily, as are fish otoliths (Panella, 1971). Growth rings in Illex illecebrosus (Lesueur, 1921) statoliths were illustrated by Lipinski (1978) with similar interpretation to that of Spratt (op. cit.). Several further attempts have been made to validate and/or to discuss age determination from statoliths (Hurley, Drew & Radtke, 1979; Hurley et al. 1983; Wiborg, 1979; Hurley & Beck, 1980; Kristensen, 1980; Lipinski, 1980, 1981; Rosenberg, Wiborg & Bech, 1981; Martins, 1982; Radtke, 1983; Dawe et al. 1984), and several other attempts are in preparation (R. J. Hanlon, G. V. Hurley, M. R. Clarke & R. L. Radtke, personal communications).

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 mode of feeding in Amphioxus is effected by–

(1) The maintenance of a stream of water through the pharynx by rows of lateral cilia on the gill-bars.

(2) The throwing out of mucus from the endostyle on to the gill-bars to serve for entrapping food-particles.

(3) The collection of food-particles by rows of cilia on the pharyngeal surface of the gill-bars; these cilia woraSkip the foodparticles with mucus into cylindrical masses and transport such masses dorsally into the dorsal groove which carries the collected masses backwards into the digestive tract.

Thus the ciliary mechanisms on a gill-bar of Amphioxus are exactly the same as those on the gill-filaments of some Lamellibranchs, as Pecten, and some Gastropods, as Crepidula.

A subsidiary mode of food-collection is effected in the buccal cavity of Amphioxus by the ciliated tract known as the wheel organ, and Hatchek's pit, which supplies mucus for entrapping food-particles. These particles are passed on to the peri-pharyngeal bands which, conduct them in turn into the dorsal groove.

The gill of Amphioxus functions mainly as a feeding organ and a water pump, and probably not at all as an organ for aerating the blood.

The mode of feeding in Ascidians is almost exactly the same as that described above for Amphioxus. Food-collection, however, in Ascidians is effected by cilia on the papillae and similar outgrowths on the gill, and is also helped in some forms by transverse waving of the longitudinal bars, by which process the food is pushed as well as lashed towards the dorsal region of the pharynx.

The behaviour of well fed cuttlefish is strikingly affected by light. When the light is bright they usually bury themselves in the gravel at the bottom of their tanks, whilst after twilight they come out of the gravel and swim around until dawn.

Cuttlefish kept in complete darkness for one to two days usually become so buoyant that they are incapable of staying on the bottom and can only remain in mid-water with difficulty.

Animals kept in artificial light and dark showed changes in density which could amount to 2%. These changes come from changes in the volume of the gas space within the cuttlebone.

The density of the cuttlefish is largely governed by light intensity and there is little indication of an inherent diurnal rhythm of density change.

The rate of uptake of liquid when the cuttlefish becomes denser is such that it is unnecessary to assume that any active process is used to pump liquid into the cuttlebone. The cuttlefish must, however, extract liquid actively from the cuttlebone to become less dense.

The fauna of a muddy area in the northern North Sea (the Fladen ground) is compared with that of a similar area in a Scottish west-coast sea loch (Loch Nevis). These areas were selected because certain similarities in environmental features and in fauna, coupled with their marked difference in biomass, make them particularly suitable for studies of the factors affecting benthic production.

For macrobenthos samples (from a grab) a coarse sieve with round holes of 1-3 mm diameter and a fine sieve with meshes of 0-5 mm side were used. Meiobenthos samples (from a corer) were sieved through a 0124 mm mesh and the total residue stained in rose bengal.

The Fladen ground, depth 140 m, had annual bottom temperatures between 6-31 and 8-22 C and salinities between 35-20 and 35-2.50. The deposit was mainly of coarse silt with abundant tests of small Foraminifera. The fauna is redescribed. The characteristic species was the foraminifer Saccammina sphaerica. By separating empty tests from living specimens it is shown that this species was not so abundant as had been thought. The main lamellibranch was Thyasira equalis, not T. flexuosa as recorded in previous work. Other important species were the polychaetes Paraonis gracilis, Myriochele heeri, Spiophanes kroyeri, Tharyx sp., Lumbrineris impatiens, and Nephthys incisa. The standing crop of macrobenthos was 6-42 g/m2 wet weight.

Hermit crabs use gastropod shells to protect their bodies and developing eggs; an inadequate supply of shells of the appropriate size will, therefore, adversely affect their growth, fecundity and longevity. Since the supply of shells is commonly limited, mechanisms that help to reduce these adverse effects will be selectively advantageous. In Pagurus bernhardus it is suggested that two mechanisms have evolved in this respect: larval settlement is encouraged in the littoral zone where gastropod species are diverse and numerous and where the youngest hermits will find growth potentially unrestricted; and females breed within their first year of life and at a size substantially below that which could be attained in the shells commonly available to them. This ‘precocious’ breeding is suggested to be an adaptation enabling hermits to overcome the problems of shell-limitation, since it frees females of the need to attain a specific age or size before reproducing - a situation which would be perilous when large shells are scarce. Males of a similar age are freed from competition for the larger shells as a result of this strategy, since the growth of the females is suppressed while they are ovigerous.

Spawning temperature preferences for sardine (Sardina pilchardus) in the eastern North Atlantic were determined from egg survey data. These were compared with climatological temperature cycles (1986–2002) derived from satellite observations, by geographical region, to predict spawning seasons. Optimum spawning temperatures were determined as 14.0–15.0°C from the English Channel to Portugal and 16.0–18.0°C for all north-west African regions. Spawning seasons were closely related to the general latitudinal trend of the annual temperature cycle, with modification by upwelling in the western Iberian and north-west African regions. Some differences between temperature-based spawning season predictions and field observations were related to variations in seasonal plankton production. Correlations in the annual time-series of favourable spawning temperatures suggested relatively strong linkages between the southern areas from Portugal to Senegal. There was no consistent relationship between annual variations in extent of temperature-predicted spawning seasons and observed field abundance of eggs.

The vocal repertoire of many delphinid odontocetes includes narrowband tonal whistles used mainly for communication. The aim of this study was to describe the whistle repertoire of short-beaked common dolphins, Delphinus delphis, recorded in the Celtic Sea between May and August 2005. The 1835 whistles recorded were classified into six broad categories and 30 sub-types, of which simple upsweeps and downsweeps were the most common. Furthermore, the parameters duration, inflections, steps and various frequency variables were measured. The whistles covered a frequency span from 3.56 kHz to 23.51 kHz and had durations between 0.05 and 2.02 seconds. Whistle parameters varied with behavioural context, group size and between encounters. The whistle repertoire of Celtic Sea common dolphins was compared to that of D. delphis from the Western Approaches of the English Channel, recorded during a survey between January and March 2004. The relative abundances of the broad whistle types did not differ between the two locations, but most whistle parameters were significantly different: almost all frequency variables measured were significantly higher in English Channel whistles. This may indicate some degree of population structuring of short-beaked common dolphins around Britain. Alternatively, the common dolphins in the English Channel may have shifted the frequencies of their vocalizations up to avoid masking by low-frequency ambient noise produced by high levels of vessel traffic in this area.

The spatio–temporal abundance pattern of 0-group sea bass, Dicentrarchus labrax, was investigated between April 1995 and November 1996 by beam trawl surveys. The highest densities of D. labrax were recorded in shallow areas. Dicentrarchus labrax density was also significantly related to water temperature and salinity, but the variation pattern was not linear. The 0-group individuals of this species first occurred on the nursery ground in May and the highest densities were recorded in June. Diet of 0-group D. labrax was mainly composed of crustaceans, the most important food items being Decapoda, Mysidacea and Isopoda. Feeding activity increased during summer. Short-term variations were related to the period of the day and tidal cycle. The growth rate determined for 0-group D. labrax was higher than those reported for the UK and northern France, and was similar to those obtained in eastern Mediterranean.

The work of F. S. Russell on plankton animals as indicators of different water masses, particularly the species Sagitta setosa J. Müller and S. elegans Verrill, and of Atkins, Harvey and Cooper on plant nutrients, have pointed the conclusion that the water in the English Channel, in the neighbourhood of Plymouth, was consistently richer in nutrients and plankton in the 5 or 6 years prior to about 1930 than it has been at any time since. (See Russell, 1935, 1936a, 1939; Cooper, 1938; Armstrong & Harvey, 1950; Harvey, 1950.) The comparative infertility of the sea in this area in the 1930's, and until the present time, has been shown not only by the low winter phosphate- maximum, and by the sparse plankton characterized by the presence of S. setosa, but also by the reduced numbers of young fishes surviving their early larval stages after the summer spawning (Russell, 1939).