A new species of the genus Lucernariopsis, of the family Eleutherocarpidae, is described.It is the second species of the genus to be found in British seas and the fourth in this world-wide genus.

The discovery of a new species of Sarsia hydroid and its medusa and a comparison of this species with Sarsia tubulosa (M. Sars) and S. loveni (M. Sars) have resolved a longstanding problem. In his detailed account of the hydroid and medusa Coryne mirabilis (now accepted as identical and synonymous with Sarsia tubulosa), Louis Agassiz (1860-2, vol. 4, pp. 189-90, 203-4, P's- 17J i8) asserted that it undergoes a change of reproduction in winter and spring. He stated that in late winter the hydroid releases medusae but that in spring the gonophores no longer develop into normal medusae, being retained on the hydranths where they become sexually mature without mouth and tentacles. He based his conclusions on a series of hydroid colonies collected on the shore. Allman (1871-2, pp. 278-9) was strongly disinclined to accept Agassiz's assertion of the specific identity of the two forms of gonophore without stronger evidence, saying that, until the two kinds were found simultaneously or in succession on one colony kept under close observation in an aquarium, the identity of the two forms could not be accepted as proved. Mayer (1910, p. 55), from personal observation of colonies collected on the coast of Massachusetts, came to the same conclusion as Agassiz, but he did not say whether he had followed the succession in an aquarium or had observed one colony throughout, and accordingly his conclusion is subject to the same criticism.

In Torbay, Nemertesia antennina (L.) hosts more than 150 epizoic species, most of which do not occur on other substrata in the area (Hughes, 1975). Five species, the amphipods Ericthonius brasiliensis (Dana), Pseudoprotella phasma (Montagu) and Corophium sextoni Crawford, and the gastropods Cingula semistriata (Montagu) and Cingula semicostata (Montagu), constitute 68 % of the free-living epizoites and are sufficiently abundant throughout the year to allow a study of their life-histories.

The survivorship of marine invertebrates that have a life span of less than 2 years is usually assessed by observing the decrease in abundance of animals from samples taken frequently throughout the life of an identifiable cohort or generation (e.g. Crisp, 1971). This method is only suitable for species with approximately simultaneous recruitment so that the animals can be aged with reasonable accuracy and the mortality before the end of the recruitment period can safely be ignored. Such age-specific survivorship data can be used to calculate secondary production by revealing the number of animals that reach successive weights (= Allen curves) (Crisp, 1971).

Larval anisakid nematodes are among the most abundant helminth parasites of commercially exploited marine fish in the North-East Atlantic. Consequently, the biology of Anisakis and Phocanema in commercially sized fish from the North-East Atlantic has been quite extensively studied in recent years (see for example Davey, 1972; Rae, 1972; Young, 1972; Platt, 1975). There is, however, little available information on the occurrence of larval anisakids in small fish or species not used for human consumption. This is an important gap in our knowledge since information on the infection of such fish will increase our understanding of the circulation of these parasites within the marine environment and the levels of infection in commercial species.

Collections of bottom-living animals from the continental slope of the northern Bay of Biscay contain a new species of Oligobrachia; this increases the number of species of Oligobrachia known from the North Atlantic to five. Oligobrachiids are quite frequently found incubating embryos and five individuals of the new species carry embryos. Oligobrachia embryos have been studied morphologically already (Ivanov, 1957, 1975; Southward & Southward, 1963; Brattegard, 1966; Ivanov & Gureeva, 1976) and should prove useful material for experimental studies in future. Incubation is also known in the family Siboglinidae, but neither embryos nor larvae have been seen in any other pogonophoran families. The Biscay collections also contain additional specimens of Oligobrachia ivanovi and these have been useful in revising the description of this rather rare species.

The Crustacea play an important economic role in the marine and aquatic environments not only as a food source but also in the productivity of the fisheries. Exploitation of these resources has led to a need for intensive culture methods which impose physiological stress on the animals and consequently increase the incidence of disease. The need to reduce the lethal and debilitating effects of pathogens has stimulated a renewed interest in the defence mechanisms of the Crustacea.

Rainbow & Walker (1977) have described the histology, histochemistry and ultrastructure of the barnacle alimentary tract and this study continues the overall investigation into barnacle digestive physiology. Possible sites of alimentary absorption in the barnacle tract have been proposed from histological (see Törnävä, 1948) and histochemical and ultrastructural evidence (Rainbow & Walker, 1977) but no direct studies on sites of absorption have previously been made. Similarly, although it has long been known that barnacles produce discrete faecal pellets (Darwin, 1851), the time interval between ingestion and defaecation has not been determined.

Nassarius reticulatus, like most other members of the Nassariidae and Buccinidae, is a scavenger. It apparently relies on the rapid detection and location of a food supply which is intermittently and unpredictably available. The olfactory reactions of Nassarius species are well-adapted for finding dead or damaged animals (Copeland, 1918). Stimuli indicating the presence of food provoke an impressive increase in activity of most starved Nassarius (Dimon, 1905; Copeland, 1918). Recently-fed whelks, however, often fail to respond to the same stimuli (Crisp, in preparation).

Analysis of the deposit-feeding bivalve Scrobicularia plana (da Costa) has been proposed as a method of assessing the biological availability of heavy metals in estuarine sediments (Bryan & Hummerstone, 1977; Bryan & Uysal, 1978). Scrobicularia has a number of attributes which are useful in this type of indicator: (i) it is common in many British estuaries, particularly in the south, and often penetrates much farther upstream than other common bivalves such as Mytilus edulis; (ii) it is a convenient size for analysis and, during its life span of perhaps 10 years, reaches a shell length of 40-50 mm (Green, 1957; Hughes, 1970); (iii) it is a good accumulator of metals and appears to reflect changes in their biological availability.

The pronounced Bohr shift of cephalopod haemocyanin may be related to the formation of octopine, rather than lactate, by cephalopod muscle. Octopine is a much weaker acid than lactate.A highly pH-sensitive oxygen binding curve would permit the efficient unloading of oxygen at the tissues even for a moderately small decrease in venous pH.

In many marine invertebrates the presence of an active transport system for the epithelial absorption of amino acids has been conclusively demonstrated (Stephens, 1968. 1972; West, de Burgh & Jeal, 1977). It has been observed by several authors that inhibition of uptake of a given amino acid can occur in the presence of other amino acids, in a manner analogous to that observed in vertebrate gut absorption systems. Some examples are the work of Chapman & Taylor (1969) on whole Nereis virens, Ferguson (1968) on the digestive glands of Echinaster spinulosus, Ferguson (1971) on whole asteroids, Bamford & Stewart (1973 a, b) on Arenicola marina gut, and Bamford & McCrea (1975) on the gill of Cerastoderma edule.

The publication in 1953 of the English language translation of Vinogradov＇s massive compilation of data upon the chemical composition of numerous animals was a valuable landmark in this field of study. Since then, papers too numerous to summarize, have appeared in the literature employing ever more accurate analytical techniques. So far as marine animals in particular are concerned, the theme which has been consolidated by such subsequent work revolves around their ability to extract and concentrate a variety of chemical elements from their environment. Frequently, however, no obvious function can be ascribed to the more obscure of these often highly concentrated elements.

Very few field studies of the population dynamics of starfish have been undertaken; such work depends upon being able to age individuals and identify age classes in the field. Information regarding growth rates in asteroids is notoriously difficult to obtain, due primarily to the absence of any method of assessing age, except where clear and obvious recruitment and regular growth provide size/age relationships. Numerous investigations of skeletal structures in asteroids by Smith (1940), Feder (1956), Hatanaka & Kosaka (1959) and Crump (1971) have failed to reveal any trace of growth lines similar to those found by Moore (1935), Jensen (1969) and Ebert (1970) in echinoids. In forcipulate asteroids, it is well established that growth depends primarily on temperature (Vevers, 1949; Hancock, 1958) and the availability of suitable food supplies (Mead, 1900; Galtsoff & Loosanoff, 1939; Smith, 1940; Vevers, 1949; Feder, 1956, 1970; Hancock, 1958). The food availability factor acts in such a way that it is impossible to tell the age of an adult starfish from its size; for example, in the spinulosan asteroid Patiriella regularts (Verrill), Crump (1969) found that specimens kept without food for 44 weeks lost 33 % of the original body weight, whilst P. regularts which had been fed on freshly killed crabs, showed a mean net increase of 629% of the original net weight over the same period.

The bipinnaria larva of the five-armed starfish Luidia sarsi Diiben and Koren is unusual among bipinnariae in being exceptionally large, and more especially in that at metamorphosis the larval body detaches from the juvenile starfish it has carried and nurtured, to continue a separate existence for a considerable time. In the closely related seven-armed Luidia ciliaris (Philippi) the larva is much smaller and the larval body is completely absorbed, as is usual with starfish larvae. In neither species does a brachiolaria stage precede metamorphosis. The bipinnaria of Luidia sarsi has been especially well described and illustrated, with a discussion of earlier observations, by Tattersall & Sheppard (1934). Recorded here are my observations on the metamorphosis of six bipinnariae of Luidia sarsi and one of Luidia ciliaris, and on the subsequent growth and habits of the young starfishes developed from them. Three of the former species metamorphosed in accordance with previous accounts, but three others differed in that the larval body was partially absorbed to a greater or lesser degree.

Various workers during the past century have figured sensory cells bearing cilia amongst the ordinary non-ciliated epidermal cells of the body surface. Similar sensory cells were also found on the buccal cirrhi, and on the velar tentacles at the entry to the atrium. This earlier work at the light microscope level was summarized by Franz (1923) in his excellent review. More recently Schulte & Riehl (1977) have re-examined the innervation of the oral region and buccal cirrhi at the ultrastructural level, and observed two types of sensory cell in these regions, distinguished by their apical structure. They suggest that these are both secondary sensory neurons (as Franz had previously surmised), but their figures hardly make this suggestion convincing. In this note we show that there is probably only a single type of sensory cell amongst the epidermal cells of the body surface and buccal cirrhi; that it synapses at its base with incoming axons of central cells, and that a different type is indeed found in amphioxus, but only in the velar tentacles.

I trust that I will not be criticized for saying that, in general, the argument between Hensen and Haeckel has been resolved. Hensen (1887, 1895) believed that true spatial and temporal heterogeneity of the plankton could be resolved by careful measurement and analyses of variance. Haeckel (1893) thought these analyses might give more information than the data possessed. Our present understanding of spatial heterogeneity, and its analysis, does not lead us to disagree with either. Investigations carried out by a number of marine ecologists have shown large-scale spatial variations in phytoplankton. Amongst many others, this feature can be seen in studies off the northeast coast of England (Cushing, 1955), in the English Channel and Celtic Sea (Cushing, 1957; Pingree et al. 1976), off Scotland (Adams, Baird & Dunn, 1975,1976) and off the coast of the Netherlands (Gieskes & Kraay, 1975). Nevertheless the statistics of sampling heterogeneous distributions is far from simple, estimates of density for instance can be greatly influenced by the sample size (e.g. Greig-Smith, 1964; Cassie, 1963). Bainbridge (1957) summarized his review by saying that patches occurred on all scales from a few feet to as much as 30 or 40 miles by 120 or 180 miles. Our present understanding of the nature of turbulence in the sea would reduce his few feet to centimetres.

In order to improve their quality before commercial distribution, oysters in the Marennes-Oleron region of France are placed temporarily in sea water in either natural basins or artificial canals known as 'claires' (Korringa, 1976). It has been known for some time that these marine enclosures provide an environment particularly rich in a variety of micro-organisms many of which are valuable sources of food thus contributing to the growth of the oysters; one species in particular, the diatom Navicula ostrearia (Gaillon) Bory, gives them a green hue and a special flavour much appreciated by French consumers (Neuville & Daste, 1972). For some years, two of us (D.N and Ph. D.) have been concerned with detailed investigations of the diatoms of the 'claires', especially N. ostrearia (Daste & Neuville, 1976).

Salpingoeca natans Grentved and 5. spinifera Throndsen have been removed from Salpingoeca James-Clark and made the nomenclatural types of Calliacantha gen.nov., and Bicosta gen.nov., respectively.

James-Clark (1876) erected the genus Salpingoeca J.-Clk, 1867 for solitary choanoflagellates with colourless, transparent, thecae.* As for most choanoflagellates the protoplasts possessed a single anterior flagellum surrounded by a hyaline collar which, when viewed with the light microscope, appeared membranous.

The family Ectocarpaceae currently contains the simplest, and probably also the most primitive, members of the Phaeophyceae. The thallus form of every species is a heterotrichous filament with little or no structural modification. Some species may possess quite extensive cortication of axial filaments by adventitious rhizoids but advanced pseudoparenchyma is never formed. Periclinal cell divisions within filaments have also been reported, particularly in the course of sporangium development, but true parenchyma is unknown. Growth of the erect system of filaments is diffuse, for although intercalary sites of relatively active cell division may sometimes be observed, these lack the permanence of position and sustained activity of true intercalary meristems. The growth of the horizontal branch system is probably mainly apical, but is also too diffuse to be considered meristematic. Sporangia and gametangia are formed from vegetative cells and occur either as intercalary structures within filaments or as modified branch apices. Sexual fusion of gametes may be isogamous or anisogamous.