On the SOND Cruise of R.R.S. 'Discovery' in 1965 a day and a night series of horizontal hauls were made with a modified Indian Ocean Standard Net (N113 H) fitted with a catch dividing bucket (C.D.B.). The hauls were of 1 h duration, made at approximately 50 m depth intervals from 960 to 40 m, at a position off Fuerteventura in the Canary Islands. This paper is one of a series by various authors on the vertical distributions of the animal groups sampled (Angel, 1969; Clarke, 1969 a; Baker, 1970; Badcock, 1970; Foxton, 1970a, b). Details of the cruise and of the hydrology of the area are given by Currie, Boden & Kampa (1969), and Foxton (1969) gave details of the sampling methods.

This paper is the second of four dealing with the calanoid copepods taken with a modified Indian Ocean Standard Net (N113H) on the R.R.S. 'Discovery' SOND cruise of 1965. Details of the cruise are given by Currie, Boden & Kampa (1969), and the sampling methods used in the N113H series are described by Foxton (1969) and by Angel (1969).

The rate of water filtration by bivalves has long excited interest, but it has in practice proved difficult to measure in conditions where the animal is relatively free from constraint. Its estimation is important from a number of aspects: feeding studies; as an indicator of the animal's reaction to its environment; and for predicting the flow of water required for the culture of economically important species. The work reported in this paper started as part of the general programme on shellfish culture in progress at this laboratory. During the development of a suitable method for studying the water requirements it became clear that one factor, water current, had a more important influence than has been generally recognized.

In a previous paper (Harris, 1972) the meiofauna of an exposed sand beach at Whitsand Bay, Cornwall, was described in relation to the physical environment. During this study special emphasis was placed on the harpacticoid copepods, of which 13 species were recorded on the beach. In the present paper the horizontal and vertical zonation of the copepod species on the beach is described. An account of seasonal changes in the copepod population will be given in a subsequent paper.

In spite of the increasing interest in the ecology of interstitial meiofauna (Fenchel, Jansson & Thun, 1967; Gray & Rieger, 1971;Jansson, 1968; Renaud-Debyser, 1963; Renaud-Debyser & Salvat, 1963; Schmidt, 1968,1969) little is known about the seasonal changes that occur in interstitial populations. A number of seasonal studies have been made of groups within the meiofauna–for example, tardigrades (Pollock, 1970) and nematodes (Skoolmun & Gerlach, 1971). However, Schmidt (1968, 1969) provides the only information for a total meiofauna population based on regular sampling over a complete year's cycle.

On rocky shores of the British Isles and neighbouring regions of the North Atlantic coastline, the sporophyte of Laminaria hyperborea (Gunn) Foslie is the dominant member of most sublittoral algal communities. The bathymetric distribution, like the geographical distribution, is extensive; L. hyperborea is often dominant from extreme low water level of spring tides (E.L.W.S.) to depths of up to 32 m. The great changes in environment encountered by this species over this wide range of distribution would suggest a highly adaptable organism. Changes in size, rate of growth and growth pattern have indeed been recorded between plants at different latitudes and different depths. Plants from northerly waters generally are much larger with longer stipes and have a greater frond area (Kain, 1962; Bellamy & Whittick, 1968; Greenhager, 1958), although Kain (1963, 1967) points out that this is often due to greater longevity of individuals rather than greater growth rates. Increasing depth affects the density of distribution; the typical L. hyperborea forest becomes more sparse until an open community, called 'the park' when first recorded by Kitching in 1941, replaces the forest at about 15 m. The plants in the open community are smaller than those in the forest and have shorter stipes (Kain, 1962, 1966, and observations described in this communication). However, despite these changes in growth,, almost no morphological variation had been recorded prior to the present investigation. More recently there has been a report of a form L. hyperborea f. cucullata (Svendsen & Kain) from deep water and waters not subject to water movement with thin enlarged fronds and short stipes (Svendsen & Kain, 1971; Kain, 1971).

The jaera albifrons Leach group of species is a common component of estuarine faunas in Britain, where each species may occur in considerable numbers. Some members of the group also occur in less variable, marine localities in Britain and elsewhere, indicating that each species is capable of survival in a wide range of salinity combinations and that the group as a whole is euryhaline (see, for example, Naylor & Haahtela, 1966; Jones & Naylor, 1971). Naylor & Haahtela (1966) showed that the four species of jaera which occur in Britain occupy preferred areas on an estuarine shore such that jaera ischiosetosa Forsman is common on stones in areas affected by freshwater seepage, jaera albifrons Leach occurs on stones either in pools or in parts of the shore where water is retained (around M.t.l.), jaera praehirsuta Forsman occurs on Fucus serratus (L.), and jaera forsmani Bocquet can be found under stones around L.w.s.t.-l.w.n.t. where there is little retention of water. A later investigation by Jones & Naylor (1971) has shown that these habitat preferences persist throughout a 2-year period, and that each of the jaera species is capable of successful reproduction and development in a characteristic pattern of fluctuation in salinity, temperature and exposure to air

Adult barnacles adhere to surfaces by a secretion released on to or forced beneath the bases. This secretion has been called barnacle cement. Carderelli (1968) calculated from crude experiments that the tensile strength of Balanus eburneus exceeded 50,000 p.si., but apart from this work no other data exist on the adhesive properties of barnacle cement. More studies have been undertaken on the biochemical composition of cement (Carderelli, 1968; Saroyan et al., 1970; Cook, 1970), but the results are somewhat contradictory.

Many animals have a diffuse extra-ocular sensitivity to light. Limited areas of particular dermal photosensitivity have been localized in, for example, Mya siphon (Light, 1930) and the tail of ammocoetes (Steven, 1951) but identification of the receptors is difficult. Even when candidate receptors are known, owing to their small size and the limitations of light microscopy, they have been imperfectly characterized (e.g. Light, 1930) and their identification questioned (Steven, 1963).

Few observations on living pterobranch hemichordates have been published. Gilchrist (1915) and Andersson (1907) have observed living zooids of Cephalodiscus; while Sars (1874), Schepotieff (1907) and Burdon-Jones (1954, 1957) have observed living Rhabdopleura. No observations appear to have been published on living Atubaria. Recently R. compacta Hincks was discovered near the Plymouth Laboratory (Stebbing, 1968) and during our work (Dilly, 1971, 1972a, b; Stebbing, 1970a, b) we have made some observations on living specimens. Attempts to keep R. compacta alive for long periods have not been completely successful (Stebbing, 1970), although Burdon-Jones (1954) managed to study the salinity tolerances of/?, normani Allman for more than 2 months in the laboratory. He has also studied feeding behaviour in living zooids (Burdon-Jones, 1957) Our observations have been made on specimens maintained in recirculation systems over periods of up to 12 weeks.

Mortality resulting from fishing of scallops (Pecten maximus L.) can be divided into the loss caused by their removal for marketing and the indirect damage inflicted during the operation both by the dredges on the sea bed and the rough handling of undersized discards on board the boat (Medcof & Bourne, 1964; Caddy, 1968). Direct fishing mortality is easily measured if both the relevant biological information and catch data are available. Indirect fishing mortality is more difficult to estimate. Deaths due to damage by the dredges cannot easily be distinguished from natural deaths, and although damage to discards can be assessed before they are thrown back (Medcof & Bourne, 1964), the correlation between such damage and subsequent mortality is almost impossible to obtain in the field.

Typically, adult digenetic trematodes are found as parasites of vertebrates, but Freeman & Llewellyn (1958) described sexually mature, unencysted digeneans from the kidney region of the mud-dwelling lamellibranch Scrobicularia plana (da Costa) collected from Chalkwell, near Southend-on-Sea, in the Thames estuary. The trematodes were identified as belonging to the genus Proctoeces (Odhner, 1911) and of the family Fellodistomatidae, subfamily Haplocladinae (Odhner, 1911). Freeman and Llewellyn considered that the features exhibited by the specimens were consistent with the description for Proctoeces subtenuis (Linton, 1907) Hanson, 1950, a species which had been recorded up until that date only as a parasite of the hind gut of marine teleosts belonging to the families Labridae and Sparidae from the Red Sea, New Zealand and the eastern seaboard of America.

The genus Chrysochromulina Lackey (1939) comprises a number of golden-brown flagellates now included in the class Haptophyceae {sensu Christensen, 1962, 1966). So far 21 species have been described and their scale morphology and fine structure are well documented.

The abundance of gastropods characteristic of rocky shores throughout the world (Southward, 1958) has encouraged investigation of their ecology and behaviour in several areas, although studies under laboratory conditions seem to have been restricted largely to the common European species Littorina littorea and Patella vulgata. Most investigations of littorinid behaviour have concentrated upon their response to light and gravity (see Newell, 1958, for a critique of earlier work), as the most important factors, after exposure, to influence life upon the shore. Variations in salinity are also significant, however, and ecological observations make it clear that littorinids are able to withstand a considerable range of salinity (Moore, 1958; Fretter & Graham, 1962; Newell, 1964; Green, 1968). But ecological studies alone do not necessarily reveal whether this capacity is to resist an adverse environment by a period of inactivity or, more particularly, to retain activity within a wide salinity range; nor do they show how far the potentialities of particular populations are related to the conditions under which they actually live. Examination of this aspect has been undertaken with L.littorea on the Atlantic coast of Canada (Gowanloch & Hayes, 1927) and with L.knysnaensis Philippi and other prosobranchs in False Bay, South Africa (Broekhuysen, 1940). However, these studies were restricted to determination of limiting salinities, without consideration of the extent to which activity occurred within the range of tolerance of the species concerned. Investigation of salinity tolerances in L.littorea is also of some general interest since, as pointed out by Newell (1958), the behaviour pattern of this species is probably fairly typical of the more mobile intertidal invertebrates.

The second recorded specimen of Stygiomedusafabulosa Russell was taken in June 1971 from 1200–1400 m in the Bay of Biscay, near the area in which the first was caught. The similarity of the two specimens of S.fabulosa suggests that Stygiomedusa stauchi Repelin, described from a single specimen taken near the Congo estuary, is a distinct species.