Trigonioids represent the most plausible marine outgroup for freshwater palaeoheterodonts, yet details of their early ontogeny are scant. We utilized museum specimens and scanning electron microscopy to characterize the prodissoconch structure of the ‘living fossil’ Neotrigonia margaritacea. This species produces a large inflated prejuvenile shell (mean length ±SD=664±16.9 μm, N=8) that lacks both an umbone and a prodissoconch II. It is concluded that N. margaritacea does not rely on planktotrophy to fuel its prejuvenile ontogeny.

In making benthic surveys it is often difficult to extract all the animals from the various sediments in good condition. Even the IBP Handbook (Holme & Mclntyre, 1971) does not give comprehensive details of methods for extracting animals from the complete range of sediment types. The greatest difficulty is presented by clays and compacted silt. In recent work we have had very satisfactory results by using the following procedure. Core and grab samples taken in the field are stored in seal-tight buckets for processing in the laboratory. In the case of grab samples taken from boats, preliminary sieving is performed on site and only the resistant sediments returned to the laboratory. The samples are broken into pieces of approximately 100 cm3 or less and stored in 5 % formaldehyde solution using a volume about three times that of the sediment. This serves to fix and preserve the fauna and also helps in the breakdown of clays. At this stage samples may be stored for a long time. Wherever layers of soft mud are found among the resistant material they are washed off, sieved and the fauna preserved separately. The resistant samples are then frozen in a domestic freezer and left for 24 h before thawing. The freezing is very effective in breaking down resistant sediments into small particles, thus releasing the animals, which can readily be removed by elutriation. Normally, most animals seem to be adversely affected by freezing in much the same way as some vegetables lose their consistency when frozen (an exception to this are members of the polychaete family Phyllodocidae). However, the prior treatment with formalin seems to protect the tissues from damage by freezing.

Changes in weight, histology and visual appearance of ovaries from a field population of Pecten maximus (Pectinidae: Bivalvia) were followed for one year. Ovaries containing fully-grown oocytes were found throughout the year, though the degree of filling varied. Spawning activity of varying intensity occurred from late March to September. Recovery with increase in gonad index followed the spawning in spring, but there were no signs of gonad growth during a stepwise decline in gonad index from June to September. Gonad index increased to a new maximum between October and December. Oogenesis seemed to be active in filled ovaries throughout the year, and no classical resting period with empty gonads was seen. Prior to and during the spring phytoplankton bloom, recruitment of young oocytes appeared inhibited in some ovaries, leading to increased accumulation of large oocytes.

Stanley Kemp, Sc.D., F.R.S., Secretary of the Marine Biological Association of the United Kingdom and Director of the Plymouth Laboratory, died on 16 May 1945 at the age of 62. His death at the height of his power has come as a most grievous blow to both marine science and zoology in general.

Vertical posture has been studied only in the scutellid sand dollar Dendraster excentricus although it has been reported in another Dendraster species and two species of laganid sand-dollars. The vertical posture has been associated with the posterior eccentric position of the apical system and petals of the test. We have discovered the scutellid sand dollar Encope michelini, which shows no eccentricity of the apical system and petals, also has the vertical posture in the population studied. Absence of eccentricity of the apical system and petals in living and fossil sand-dollars does not indicate absence of the vertical posture.

The feeding habits of Polyacanthonotus rissoanus, the sixth most abundant species below 1000 m on the deep slope of the Catalan Sea (western Mediterranean), were studied in the Mediterranean Sea. Samples were obtained at depths between 1000 and 2250 m. Diet was analysed for two seasons (summer and autumn) and three different bathymetric strata. The most important food items found were small epibenthic and suprabenthic crustaceans and polychaetes, and occasionally other groups such as Priapulida, Gastropoda and Foraminifera. At 1000–1425 m, the mysids were preferential prey, while in summer at all depths analysed, isopods were a dominant prey. Polychaetes have certain incidence in the diet only at 1000–1425 m, being a dominant prey in autumn. Individuals at the 1000–1425 m depth ingest larger numbers of prey of higher average sizes than those at 1425–2250 m. The scarcity of resources below 1200–1400 m resulted in diversification of diet and encouraged preying on deposited foraminiferans, molluscs or moving copepods.

The response of the shore crab Gaetice depressus to predation risk stimuli of either the octopus Octopus vulgaris or crushed conspecifics was examined at two different time phases in the activity rhythm (active and inactive period) by laboratory experiments. When octopus chemical stimuli were introduced to the experimental aquarium, the crab activity decreased in the active period (night) but not in the inactive period (daytime). When the chemical stimuli of crushed G. depressus were introduced, the activity of the crabs increased in the inactive period although the stimuli decreased the activity in the active period. This indicates that G. depressus adjust their anti-predator response according to a combination of the type of predation risk and also the activity rhythm.

One of the lobsters kept in the tanks of the Plymouth Laboratory moulted on the night of 2 0 August 1940. This opportunity was taken to examine the changes in water content and osmotic pressure of the freshly moulted as compared with unmoulted lobsters. Though only one recently moulted individual has been examined, the results seem to be worthy of note since so far as we are aware no data are available on the subject in regard to Homarus. The biology of moulting among lobsters has received the attention of many investigators (vide Herrick (1895) and Drach (1939) for summary and literature).

The water content was determined by distilling the fresh lobster together with a known weight of sea water under xylol. This method is a modification of that of Dean and Stark which one of us (A. G. L.) has tried on a number of animals and found to give accurate results. The density was estimated by a modification of a method previously described (Lowndes, 1938). Osmotic pressure of blood and the external medium were measured by Baldes's (1934) modification of the Hill thermoelectric technique, as employed by one of us (N. K. P.) in the study of prawns and other crustaceans. The water content of the moulted skin was calculated from its dry weight taken after dehydrating in a hot air oven for 48 hr. at 105° C. Osmotic pressure was measured 17±6 hr. after moult; density and water content after 34±6hr. The temperature of sea water at which the density was estimated was 17° C.

The taxonomy of six species and one subspecies of Natatolana, which have previously been recorded from the north Atlantic Ocean and Mediterranean Sea, is reviewed. Natatolana caeca, N. gallica, N. gracilis and N. neglecta are redescribed from the type material. The location of possible type material of N. borealis is reported and a redescription of this species is provided, based on material from the type locality. Natatolana neglecta var. imicola is recognized as a valid species. Natatolana schtnidti is regarded as a junior synonym of N. imicola based on comparison of type material and this material is used to redescribe the species. Distribution records for these species are summarized from examination of material held in various collections and a key to separate these species is provided.

In 1926 Pelseneer discovered the eggs of Trivia europea on the French coast. These he found were laid in capsules embedded in the compound ascidian Polyclinum luteum, the molluse biting a hole and laying its eggs in a vase-like capsule completely enveloped in the ascidian except for the wide lip of the vase which projects freely and can be easily seen with the naked eye (Pelseneer, 1926, Figs. 11–12). He also hatched some larvae from these eggs which were very interesting, as they possessed an accessory shell somewhat similar in shape to the Echinospira of Lamellaria perspicua. He did not obtain the eggs directly from the Trivia and was not able to keep the larvæ alive more than a few days. In his paper he expresses the hope that some worker will confirm his observations experimentally. This I am now able to do, having procured the eggs actually laid by the Trivia, hatched them out and kept them alive for more than a week, afterwards collecting the larvæ from the plankton from stages which exactly corresponded with those from the egg up to late stages which metamorphosed into young Trivia, and young stages of Trivia feeding on compound ascidians which corresponded with the metamorphosed forms.

Trivia europea is common at Plymouth between tide-marks and in a few fathoms of water; occasionally further out in deeper water. Records are available from the shore to the region beyond the Eddystone.

1. On storing, sea water suffers a decrease in pH value. The amount of change varies from that produced by adding 1·0 c.c. of N/100 acid to 100 c.c. of sea water, up to that due to adding about 2·5–3·0 c.c. The decrease is due to the production of carbonic acid by organisms.

2. The change corresponding to 1·0 c.c. of acid, as above, is equivalent to that produced by the complete oxidation of 3 milligrams per litre of a hexose sugar, which requires 3·2 mgrms. per litre of oxygen. This is the minimum value, from 8·0–9·6 mgrms. corresponds to the higher values of acid. Figures for oxygen consumption by estuarine waters, which are available for an approximate comparison, show that 1·5 mgrms. of oxygen is not often exceeded in estimations by means of alkaline permanganate. The highest of this series is 5·6 mgrms. It is suggested that the different results given by the two methods are due to the fact that respiratory changes taking place in the water during storage set free much of the organically combined carbon before the oxidation by permanganate has been started. Determinations on freshly drawn filtered sea water give, according to Raben, 7·5 mgrms. of hexose or 8·0 mgrms. of oxygen consumed.

3. It is probable that the change in pH value on storing indicates the amount of plankton present, at any rate when sewerage contamination is negligible. It appears that water near the surface, at 20–25 metres and sometimes at the bottom, 70 metres, is particularly subject to change during storage. Four cases out of seven showed marked decreases in pH value at 20–25 metres, and two others exhibited the change to a less marked degree.

4. The total amount of carbon, reckoned as hexose, which is set free during storage by respiration in sea water at E1 is about twice that photosynthesised between July and December, taking for this the minimum value 3 mgrms. per litre, namely a total of 6 mgrms. per litre. Considering the column of water from bottom to surface, this is equivalent to about 500,000 kilograms per square kilometre in the English Channel off Plymouth.

In a previous paper an account was given of the breeding and growth of Sagitta setosa throughout a year (2). The results appeared to show that the last spawning took place in October and the resulting offspring lived through November and December without maturing and that by February there were indications that a number were spawning. At the end of the following April and beginning of May a complete spawning population was formed. Owing to the large size at which these matured it was assumed (2, p. 148) that they had been the offspring of adults spawning in February. The true trend of events was however by no means clear as the increase in average size from January to May was very even (2, Plate II). There was a distinct difference at this period between S. elegans and S. setosa. In S. elegans a spawning population of individuals all about the same length was produced in February which apparently gave rise to a brood which had grown to a large size by April and May, and the change in size from February to May was much more abrupt than in S. setosa (1, Plate I). It was clear that while the February curve for S. elegans showed very little variation in size for the majority of the population caught, the population in May tended to be very widely dispersed. In S. setosa, on the other hand, there was a gradual narrowing down of the dispersion until a spawning population with little variation in length was produced by May.

The diversity and distribution of the Bivalvia fauna is examined in the various seas of Greek territorial waters. There is a statistically significant correlation between the bibliographical sources and the recorded variety of Bivalvia at any given area, with the deeper areas containing fewer species. Attention is given to some species ‘introduced’ into the area.

Cluster analysis, based on the species present at 30 regions which represent distinct geographical and ecological units, do not show any differentiation that corresponds to a geographical pattern. However, a distinct group is associated with the deeper open areas, which suggests that ecological parameters, such as depth and degree of enclosure, play an important role in the distribution of species.

An ecologically unique cirripede, Octolasmis unguisiformis sp. nov. (Cirripedeia: Thoracica: Poecilasmatidae), was found to be ectosymbiotic with an ocypodid crab, Macrophthalmus milloti, on tidal flats of the Amami Islands, the Ryukyu Archipelago, Japan. The cirripedes were attached to the ventral side of the crab carapace, around the bases of the first and second ambulatory legs. The cirripedes resemble the chelipeds of male host crabs. Adult cirripedes were found only on female crabs, whereas juvenile cirripedes were present on crabs of both sexes, suggesting that the survival rate of the cirripedes on female crabs was higher than that of those on male crabs. The cheliped-like appearance and female-biased distribution of the cirripedes are discussed from the standpoint of mutualism between the crab and the epizoic cirripede.

A large planktonic ciliate, Pseudotontonia cornuta, was observed during a cruise in the North Sea, Denmark, in summer 2001. Live cells as well as fixed and protargol-stained specimens were studied. The species possessed the characteristic tail of Tontoniidae, somatic ciliature classifying it as a Pseudotontonia, and cell proportions and oral ciliature corresponding to P. cornuta. Observation of live cells, however, revealed distinctive features as chloroplast-containing tentacles emerging just below the apical membranelles and an S-shaped proximal rim of the left margin of the oral cavity. These characters are eye-catching in live specimens, but have passed unnoticed till now because all previous studies on P. cornuta have been made on fixed samples.

We show in this paper that amphioxus (Branchiostoma lanceolatum) is capable of collecting sub-micron particles on its mucous filter. This is made by an endostyle in some respects simpler than those of tunicates, and that unlike the filters in tunicates, the strands of the amphioxus filter are sticky. It therefore does not act simply as a sieve.

The age, growth, longevity, mortality and reproductive parameters were estimated for Dipturus oxyrinchus from the Gulf of Gabès (Southern Tunisia, central Mediterranean Sea), collected monthly during 2007 from commercial fisheries. The present study provides the first data on age and growth of this species in Tunisian waters, as well as additional data on its reproduction. A total of 240 females (16.5–105 cm total length (TL)) and 280 males (15.5–95 cm TL) were examined to study the reproductive cycle. A subsample of 285 specimens (175 females and 110 males, ranging from 15.5 to 105 cm TL) were analysed to study the age and growth. The oldest female in this study was 25 yr and 105 cm TL, whereas the oldest male was 22 yr and 95 cm. The annual deposition of growth bands was verified by marginal increment and edge analysis. The von Bertalanffy growth parameters were L∞ = 123.9 ± 2.56 cm, K = 0.08 ± 0.004 yr−1 and t0 =  −1.26 ± 0.04 10−1 yr for females and L∞ = 102.1 ± 3.23 cm, K = 0.12 ± 0.007 10−3 yr−1 and t0 = −1.18 ± 0.03 10−1 yr for males. Growth was not significantly different between sexes. The maturity size was 72.05 cm for males and 82.1 cm for females. The maturity age was estimated to be 11.95 and 13.96 years, respectively, for males and females. Size and age at maturity were not significantly different between sexes. The estimated longevity was 26.18 and 38.84 yr for males and females, respectively. Based on life history parameters, natural mortality was estimated at 0.53 yr−1 for females and 0.41 yr−1 for males.

Platynereis dumerilii is an emerging model system for both comparative developmental biology and ecotoxicology. As such it would be extremely valuable to be able to map the location of genes and markers in its genome, in order to understand how the genome changes or has changed, either due to chemical and environmental insults or during evolution. Here we report the adaptation of the technique of chromosomal fluorescence in situ hybridization (FISH) to P. dumerilii for the localization of single-copy genes. Also the duplicated ribosomal gene cluster of this annelid is more reliably revealed with FISH than with the previous technique of silver staining. This duplicated ribosomal cluster correlates with polymorphisms in the internal transcribed spacer (ITS) regions, which has implications for the use of these regions in phylogenetic or population biology work.

The original description of Tegula ignota was based on three shells found on the coast of Totoralillo Sur, northern Chile. Until now, there are no reports of living specimens of the species. The present study redescribes this snail based on shell, radula, epipodium and mantle characteristics observed in living specimens collected from the subtidal zone of La Boca, central Chile. Additionally, we extend the distribution of T. ignota more than 700 km to the south-eastern Pacific with additional material. Molecular analyses based on the 16S ribosomal DNA mitochondrial gene show that T. ignota is most closely related to Tegula atra than other Chilean species of Tegula. Voucher specimens of T. ignota were deposited in the Museo Nacional de Historia Natural de Chile.

The anatomy of Dinophilus, a genus established by Oscar Schmidt in 1848, has formed the subject of several memoirs, amongst which attention must be specially called to the recent papers of Korschelt (6), Repiachoff (12), and Weldon (13). A complete account of the synonymy of the genus was given by v. Graff in 1882, whilst Korschelt (7) has, within the last year or two, published a review of the facts known with regard to the anatomy of the various species of Dinophilus.