The writer has recently reared a species of hydroid at Plymouth, which, in the vegetative state, might easily be confused with Slauridium productum Wright, 1858. The original creeping stolon from which the colony developed was found on a piece of dead Eunicella verrucosa (Pallas) dredged by the S.S.Salpa near Stoke Point on March 9th, 1936.

When isolated in a finger-bowl with “outside” sea water the stolon bore no polyps and showed no sign of activity, but three weeks later a single polyp had developed (Fig. 3). From its close resemblance to the figures given by Hartlaub (1895) for S. productum, it was at first assumed to be this species and was carefully watched and fed in the hope of rearing the medusæ from it. After a period of time, however, when the colony had increased considerably in size, styloid gonophores were developed.

The type of growth of the fully grown colony is shown in Figures 1 and 2. The stems are elongated and slender, bearing polyps at intervals. Polyps are borne at the summit and also on branches of the main stems. These branches usually arise from one side only of the main stems and it is probable that under natural conditions in the sea these main stems are really stolons. It is also likely that in nature the intervals between the polyps are fairly short. The whole colony has a faint yellow-brown colour which becomes reddish-brown in the polyps and the upper part of the hydrocaulus.

Abundant species are typically also viewed as ecologically dominant, and are frequently used to characterize the communities in which they live. Such characteristic assemblages may also be used as indicators of environmental conditions, such as relative stability. Fossil and modern turritelline gastropods are often the most abundant species in the marine assemblages and communities in which they occur, forming ‘turritelline-dominated assemblages’ (TDAs). We use data on modern Turritella bacillum from waters around Hong Kong as a case study to analyse fluctuations in abundance over 25 years. While turritellines were not always dominant in the area surveyed (~1650 km2), populations were notably persistent, and rebound after decline of abundances occurred within ~5 years at some sites. δ18O sclerochronology suggests that individuals were ~1–2 years old. It is also notable that T. bacillum was found to be abundant at salinities as low as 10–15 psu, despite the general characterization of turritellines as fully marine. Comparison with data on modern T. communis in the western English Channel corroborates this pattern, as localized sites of high abundance also appear transient. These results have implications for the interpretation of TDAs in the fossil record: they may signify the cumulative result of short-lived, spatially restricted populations, possibly resulting from essentially stochastic larval settlement. This suggests that the palaeoenvironmental setting of fossil TDAs does not always control their occurrence on short temporal scales.

The spaces between sand grains are home to a myriad of microscopic marine eukaryotes, including kalyptorhynch rhabdocoels equipped with an eversible proboscis that enables them to capture microscopic prey living in these environments. The structure of the kalyptorhynch proboscis separates the two major subclades within the group: the Schizorhynchia (bifurcated proboscis) and the Eukalyptorhynchia (unbranched proboscis). A survey of meiofaunal metazoans in the Pacific north-west led to the discovery of three new schizorhynch species (Undicola tofinoensis gen. nov., sp. nov., Schizorhinos vancouverensis gen. nov., sp. nov. and Linguabana tulai gen. nov., sp. nov.) and two new eukalyptorhynch species (Thinodactylaina tlaoquiahtensis gen. nov., sp. nov. and Rostracilla nuuchahnulthensis gen. nov., sp. nov.). This survey also recovered the putative cosmopolitan eukalyptorhynch (Polycystididae) Gyratrix hermaphroditus Ehrenberg, 1831. We performed molecular phylogenetic analyses on 18S rDNA sequences from all five novel isolates and from all available kalyptorhynch species in GenBank. The molecular data supported the monophyly of the Eukalyptorhynchia and Schizorhynchia and helped demonstrate the boundaries between different species within the Kalyptorhynchia.

The in situ growth rates of marine planktonic ciliates from Plymouth Sound were determined after fractionating the natural community into several size categories to remove predators of different sizes. Total community in situ growth rates varied from 0·01 to 0·57 d−1 according to fractionation treatment, with the four most abundant taxa, comprising three species of Strombidium, and Mesodinium rubrum, achieving maximum in situ growth rates of between 0·41 and 0·68 d−1. These values are approximately half the maximum theoretical rates calculated indirectly using an equation which relates ciliate growth to cell size and temperature. Given the conservative nature of in situ growth rate measurements, the growth rates reported here appear appropriate for a natural ciliate community growing within a nutritionally favourable environment.

When Michaelsen (1923) described a species of didemnid from Heligoland, he stated that it was very similar to Leptoclinum maculosum Milne Edwards (1841), so far as may be judged by external appearance, but since no adequate description of this latter existed he proposed to call his Heligoland form by a new name, Didemnum helgolandicum, rather than use an old name which might well be wrong. Neither Michaelsen nor Hartmeyer, who described further details of D. helgolandicum (1924), was able to compare it directly with specimens of D. maculosum from the Channel coasts whence it was first described by Milne Edwards. Through the kindness of the directors of the Zoological Museum of Copenhagen and of the Biological Station of Roscoff I have been able to obtain specimens of both these forms and to compare them with specimens collected around Plymouth and on the coast of North Wales, and with specimens of D. candidum Savigny, collected at Naples, and from the Red Sea, and of Trididemnum alleni Berrill, collected around Plymouth.

A new species of calanoid copepod, Centropages aegypticus sp. nov. collected from the Egyptian coasts of the northern Red Sea is described. This species is unique in having two pointed conical processes on the dorsal surface of cephalosome in both sexes, female genital compound somite with irregular-surface outline of the right swelling part and transverse dorsolateral row of spinules on the left side, 2-segmented exopod of the female leg 5, asymmetrical medial processes of the female leg 5, of which the left one is longer and medially-curved and the right one with oblique row of thick spinules, and a club-shaped medial seta on the third exopodal segment of the male leg 5. The new species is similar to C. tenuiremis, but is not assigned to the same species group as the latter species or to any other groups.

Paratectonatica tigrina employs three predatory tactics against bivalve prey: wall-drilling, edge-drilling and non-drilling (suffocation) tactics. In this study, we conducted laboratory experiments to examine the predator–prey interactions between the naticid gastropod P. tigrina and two species of bivalve prey, Ruditapes philippinarum and Meretrix lusoria, and to investigate how predatory tactics differ for the bivalve species. Predation success increased with the shell weight ratio between predator and prey, however, there was no significant difference among prey species. The shell weight ratio significantly differed (P < 0.05) between predatory tactics against R. philippinarum, but not against M. lusoria, implying that P. tigrina determines its predatory tactics based on the shell weight ratio for R. philippinarum. However, we observed that feeding duration was not influenced by shell weight ratio or prey species, even though data were separated for each predatory tactic. These results suggest that there is no difference in feeding efficiency based on shell weight ratio between prey species and between predatory tactics. Paratectonatica tigrina may alter its predatory tactics suitably depending on the prey species and the relative size difference, despite the same feeding efficiency.

In the undisturbed sea urchin embryo, cleavage of the blastomeres is invariant and gives rise to five polyclonal territories that are each defined by the larval structures to which they give rise, and by unique programmes of gene expression. These territories are the aboral ectoderm, the oral ectoderm, the vegetal plate, the skeletogenic mesenchyme, and the small micromeres. Structural gene markers for four of these territories (all except the small micromeres, which participate in later development) have been cloned and characterized, and the regulatory domains of several of these genes have been mapped to the level of specific protein-binding sites.

Nitzschia alba (Bacillariophyceae), a colourless (apochlorotic) pennate diatom, was found on the surface of seaweeds collected from the Clyde Sea area between August and December, 1994. This is the first record of N. alba in UK waters. Nitzschia was found to replicate much more rapidly than heterotrophic protists of similar size. At 20°C, cells divided in just 6.9 h and even at 5°C the generation time was only 38.2 h. The ecological importance of these diatoms has been overlooked by microbial ecologists despite the high productivity of coastal ecosystems and recent work that has shown that Nitzschia can utilize seaweed phycocolloids and invade damaged seaweed tissue.

A new species of Ophlitaspongia (Porifera: Microcionidae) from wave-exposed sublittoral rock in the north-east Atlantic is described and compared to the two other species recorded from the genus in the north-east Atlantic. The species known as Ophlitaspongia seriata is considered to be a junior synonym of Halichondria panicea. Consequently, the name O. papilla has been reinstated. The other recorded species O. basifixa, is from deep water. Ophlitaspongia basifixa has characters which differentiate it from Ophlitaspongia sp. nov. The genus Ophlitaspongia has been separated from related genera and reinstated for species in the North Atlantic.

Size distribution and swimming activity of the sea scallop, Placopecten magellanicus, were measured in situ from high-definition video recordings collected by a remotely operated vehicle on a fished scallop bed on German Bank, Gulf of Maine in August 2010. Scallop densities ranged from 0.004 to 3.89 m−2 and shell height (SH) ranged from 16.3 to 193.8 mm. The size distribution was bimodal, with high abundance from 20 to 40 mm SH indicating a recent recruitment event in the area. The low abundance of scallops >100 mm SH was likely due to the active fishery in this area. Of 535 observed swims, 200 were characterized for swim distance, time, velocity and distance travelled per adduction. The size of scallops observed to swim ranged from 18.9 to 99.9 mm SH. Both swim time and swim distance increased linearly with SH, and quadratic relationships were observed between velocity and SH, and between distance travelled per adduction and SH. Swimming velocities peaked at ~ 50 cm s−1 for scallops between 60 and 80 mm, and maximum velocity was 103.2 cm s−1observed for an individual of 64.0 mm SH. Our study provided a unique opportunity to investigate size distribution and associated swimming activity of scallops in their natural habitat, rather than in a simulated study in the laboratory, and at depths not reachable by SCUBA diving.

1. A special study has been made of a small Metridiuni-like anemone found at Dingle, Liverpool, in comparison with the typical form of Metridium senile (L.) var. dianthus (Ellis).

2. Penicilli, formerly believed to be absent from the acontia of typical M. senile, have been discovered in abundance in the young, but rarely in the adults. In young and sexually mature specimens of the Dingle anemone they are also abundant.

3. There is close agreement between the anatomy of the Dingle form and the typical M. senile.

4. A considerable amount of variation occurs in the Dingle anemone, as in M. senile var. dianthus and M. marginatum, Mime-Edwards.

5. The resemblances and differences between the Dingle form and M. senile indicate that the former is a dwarf variety of the latter.

6. The discovery of an abundance of penicilli in the acontia of young typical M. senile and mature specimens of the Dingle variety, in conjunction with the great amount of variation in the genus Metridium, suggests that a reconsideration of the systematic position of the genus is necessary and would justify either the restriction of the family Metridiidæ to the single genus Metridium, or else the fusion of the Metridiidæ with the Sagartiidæ. The sum of the evidence appears to lie in favour of placing the genus in a family by itself.

A new species of Listriella is described and figured from maerl deposits in Kilkieran Bay, Co. Galway. The holotype of the only other British species is figured for comparison. The amphipod fauna of Kilkieran Bay (Co. Galway) maerl is compared with that of Eddystone shell gravels.

Leptoclinides faeröensis Bjerkan (1905) is a little-known boreal species which has been found only in the Atlantic Ocean (Fig. I). The most northerly record is from a little south of Spitzbergen, the most southerly from 37° 08' N., off the North American coast. It occurs on the coast of Norway and in the Faeroe Islands, but it has not been reported nearer to Plymouth than these two localities. Most records are from deepish waters, though it occurs in the sublittoral zone along the Norwegian coast. It was in this zone, at Looe Island (50' 20' 24“ N., 4 °26' 53” W.) near Plymouth, that we found a specimen of this species growing on a rock about 80 cm. below O.D.—just sufficiently low for it to remain covered by a few centimetres of water at the lowest tide of the year, the equinoctial spring tide.

The summer vertical distribution of appendicularian species was analysed at 22 stations in the central Cantabrian Sea by means of vertical tows covering the surface, thermocline and deep layers. According to their preference for shallower waters, the appendicularian species could be arranged on the series Oikopleura longicauda (Vogt), Oikopleura fusiformis (Fol), Fritillaria pellucida (Quoy & Gaimard) and Oikopleura rufescens (Fol), with Oikopleura dioica (Miiller) in an uncertain position, probably closer to the end of this series. Principal components and correlation analyses suggest that a temperature gradient causes this pattern, which agrees with previous findings made at very different temporal and spatial scales. By means of particle-size spectra, it is shown that those oikopleurids that prefer cold, deep waters, O. fusiformis and O. rufescens, co-vary with a coefficient of particle-size quality. The lower the temperature, the lower the proportion of small, ingestible particles to large inlet-filter-clogging particles. This is proposed as an important reason for the presence of inlet filters in oikopleurids.

The ultrastructure and dimensions of the solenocytes of Branchiostoma lanceolatum are reviewed briefly. The functional ability of these units is calculated upon theoretical grounds in a manner similar to that applied to flame cells. Their more delicate construction would suggest that Branchiostoma would have great difficulty in maintaining any significant osmotic pressure difference between the medium and its body fluids.

The blue crab Callinectes sapidus is an important ecological and commercial species. It plays a fundamental role in the structure and function of coastal benthic food webs, with global catches of ~74,357 tons. This is the most exploited portunid species in Brazil. However, few studies about the ecology and population dynamics of C. sapidus have been published. This study aimed to analyse the preferred areas for the spatial distribution of juveniles and moulting individuals of C. sapidus in shallow areas of the Patos Lagoon estuary and the adjacent marine reproductive area, and their relation to water and sediment characteristics. Juveniles and moulting individuals preferred the embayment of the upper estuary, where the sediments are finer, with higher contents of organic matter and the presence of submerged vegetation. There was also a temporal variability in the abundance of juvenile size classes, with two marked increments of smaller individuals: (1) in late spring and summer and (2) in winter, indicating two recruitment peaks. Unusual environmental conditions in the summer of the first year, with an increase of fine sediments and organic matter, combined with low salinities in the adjacent marine area, allowed recruitment of individuals there. We suggest better attention to the embayment around the Marinheiros Island (considered here as upper estuary) for management and protection measures due to the overlapping of recruitment preferences of the blue crab, pink shrimp and fish species in this area.

In a study of the breeding biology of Euchaeta norvegica (Boeck), Hopkins & Machin (1977) analysed the placement and frequency distribution of spermatophores on females. They found the number of spermatophores on sampled females to be underdispersed relative to the Poisson distribution and concluded that ‘virgin’ females are more attractive to males than females with spermatophores attached. They fitted the Greenwood & Yule (1920) model but drew no conclusions.

The type of question which may be studied by fitting such a model is whether the attraction of males to ‘non-virgins’ is independent of the time since the first spermatophore was attached and also independent of the number of spermatophores already attached. This problem has been further investigated by fitting a version of the Greenwood & Yule model based on asynchronous recruitment of mature females. This version of the model is fully described in Schweder (1979); in this paper the results and biological implications are discussed.

The specimens conform to a type which appears to be fairly well known to Grimsby fishermen, and fish merchants, and which is always regarded by them as the offspring of the parents mentioned in the title. The object of the present note is to discuss the probabilities of the correctness of this diagnosis as fully as the material allows. The form can hardly be said to be rare, since within two years I have secured three specimens, while I have heard of several others having been present in the market. In some old manuscript notes kindly lent me by my friend Mr. G. L. Alward I find descriptions which apply to two fish of the same type, while Dr. Günther tells me that he has received several from London fish merchants.

The Amphipoda dealt with in this paper were collected in August, 1906, by Dr. Allen, to whom I am indebted for the opportunity of examining them.

The collection contained thirty-five species (belonging to twenty families), of which one only, Tryphosites alleni, is new to science. Five others, Stenothoe richardi, Syrrhoites walkeri, Syrrhoe affinis, Eusirus biscayensis, and Rhachotropis rostrata, are recorded for the first time since their original discovery. The geographical range of five species has been considerably extended, viz. Syrrhoe affinis, Tmetonyx similis, Sympleustes glaber, Epimeria parasitica, and Laetmatophihis tuberculatus; the four last forms have not been hitherto recorded with certainty south of Norway.