(1) Adults of Audouinia tentaculata Montagu were induced to spawn in the laboratory; the eggs were fertilized and the larvæ reared to metamorphosis and early bottom stages for the first time.

(2) The larvæ are yolky and do not feed. They have a broad prototroch and telotroch and a broad neurotroch. The ciliation of the head is rather complex. There are no bristles. When about ten days old they metamorphose.

(3) During metamorphosis most of the cilia, except those of the neurotroch, disappear and their cells are absorbed internally.

(4) Bristles appear for the first time a few days after metamorphosis. After a while branchiæ appear, followed by what are apparently tentacular filaments situated on segments anterior to those on which they occur in the adult.

(5) Discussion centres on the position of the tentacular filaments and the first pair of branchial filaments in the young worm as compared with the adult. The segmentation of the anterior achaetigerous region also receives attention.

The pigments of the polychaete Sabella penicillus L. were reinvestigated. In addition to zeaxanthin and traces of lutein, a series of carotenoids which may represent steps in the formation of canthaxanthin have been found. These are β-carotene, isocryptoxanthin, echinenone, 4-hydroxy-4′-keto β-carotene and canthaxanthin. No astaxanthin was found. In two other sabellids, Myxicola infundibulum (Renier) and Megalomma vesiculosum (Montagu), astaxanthin was confirmed as the major pigment and the presence of echinenone was established. Attention was drawn to the similarity of the pigments of Sabella penicillus with those of other invertebrates and it has been suggested that in invertebrates a common pathway for the formation of canthaxanthin may exist.

Larvæ of Nereis pelagica Linnæus were reared from the egg, and the young worms, which developed from them, to the age of one year.

The larvæ from an early stage possessed three chætigerous segments. At first after hatching they swam strongly by means of a prototroch, an akrotroch and three paratrochs, but as the cilia gradually disappeared they crawled more and more, finally abandoning swimming altogether.

The head developed a pair of tentacles anteriorly and a pair of palps ventrally. A pair of tentacular cirri arose posterior to the prototroch and a little later a second pair ventral to them.

The first pair of parapodia lost their bristles, and a lobe which had grown out between the noto- and neuropodial chæta-sacs became a third and posterior pair of tentacular cirri. Much later a fourth pair developed ventral to them.

About the time when the larvæ ceased to swim (18.days old) a fourth pair of larval parapodia (third adult pair) appeared, to be followed by a fifth, sixth, etc. At sixty-five days old worms had about twentyone pairs of parapodia, at one year they had sixty and were then about 1-5 cm. long.

During larval development a constant succession of bristles was seen. In the earliest stages the bristles were mainly homogomph spinigers with long appendices; later these fell out and were replaced by homogomph and heterogomph falcigers with shorter appendices. Later still these were replaced by bristles of the adult type.

It is pointed out that these larvæ differed from those which Herpin reared in that they hatched earlier and instead of crawling as soon as liberated they swam for several days by means of their ciliated girdles.

Filtration rates for Phallusia were computed from the rate of clearance of sus-pensions of colloidal graphite and of the flagellate Isochrysis. Rates varied from 825 ml./h to 5100 ml./h for animals between 8 and 128 g wet weight (40–336 ml./h/g wet weight; 88–570 ml./h/mg nitrogen). The greater part of this current is ciliary; less than 2 % is accounted for by squirting. Squirting thus plays but a minor role in maintaining the feeding current. Its probable function is perhaps more comparable with the expulsion of pseudofaeces in filter-feeding molluscs.

1. Horizontal hauls were made with a “stramin” ring-trawl and a silk net at different depths in 1924 and 1925 to determine the vertical distribution of the pelagic post-larval stages of Teleostean fish in daylight. The depths at which the nets fished on every occasion were obtained by means of a graphic depth-recorder.

2. It was indicated that there are specific differences in the behaviour of the post-larvae of various fishes as to their vertical distribution in daylight, some preferring the surface layers, others apparently indifferently distributed from surface to bottom, and others preferring the deeper layers and avoiding the surface; of these last it was found that some

species became abundant at deeper levels than others. A tentative list of distribution types is given on page 107. 3. Eesults emphasise the necessity when examining the horizontal distribution of young fish of sampling all layers : oblique hauls are to be desired fishing at as many levels as possible. 4. Mention is made of seasonal distribution : the year 1924 appeared to differ from 1925 in that certain post-larvae which were prevalent in the plankton well into June or July in the former year were cut short a month earlier in 1925.The post-larvae of Molva molva and of Lophius piscatorius were unusually abundant in 1924 ; post-larval Gobies (Gobiidce) and Wrasses (Labridce) were extremely scarce in 1925 during the months April to beginning of August.

Siboglinum ekmani can accumulate labelled alanine, glycine, phenylalanine, glutamic acid, galactose, glucose, mannose, acetic acid, palmitic acid, lactic acid and glycollic acid from sea water at concentrations between 1 and 100 μM/1. Uptake of fructose and mannitol was not detected. The neutral amino acids were absorbed against a concentration gradient, probably by a carrier-mediated transport mechanism, and similar mechanisms may exist for acidic amino acids and glucose. Most of the compounds entered into the metabolism, but 90% of the glycine accumulated was retained as free amino acid. The presence of glucose appeared to depress uptake of alanine, but uptake of glucose was stimulated by alanine.

A local population of the introduced green macroalga Codium fragile ssp. tomentosoides was investigated in Oban in the district of Argyll, western Scotland. Periodic surveys demonstrated that sacoglossan densities (Elysia viridis and Placida dendritica) were unusually high in 1997 and early 1998, slug herbivory noticeably damaged algal thalli, and the local algal population was decimated. These patterns provide indirect evidence of the significance of slug herbivory on the introduced alga.

Size-at-maturity, often used by fisheries managers to specify reference points, was estimated for Cancer edwardsii, the most intensely exploited brachyuran crab in Chile, using morphometric data and observation of the gonadal cycle. Sampling was conducted in Chiloé Island, the principal landing region. Several morphometric measurements of secondary sexual characters were recorded for both sexes. Their size-dependence was investigated in search of ontogenetic allometric changes. Six stages of maturity were established for females, and four for males, on the basis of macroscopic and histological observation of the reproductive system, allowing distinction between adults and juveniles. Females and males, on average, attained full development of secondary sexual characters at 106 and 118 mm carapace width (CW) respectively. The CW at which 50% of females and males have gonads of adult appearance was around 101 mm. Current minimum legal size is 120 mm CW, seemingly high enough for conservation purposes. This management control, however, is unlikely to provide effective protection due to the high proportion of crab of sub-legal size in the landings. Traps with escape vents could be introduced in this fishery in order to ensure its sustainability.

Spectral sensitivity, visual pigment absorbance spectra and visual pigment opsin sequences were examined in younger shallow-living and older deep-living instars of the ontogenetically migrating lophogastrid Gnathophausia ingens. Spectral sensitivity measurements from dark adapted eyes and microspectrophotometric measurements of the rhabdom indicate maximal sensitivity for long wavelength (495–502 nm) light in both life history stages, but the younger instars are significantly more sensitive to near-ultraviolet light than the adults. Both life history stages express the same two opsins, indicating that there is no ontogenetic change in visual pigment complement between life history stages. Chromatic adaptation shifted the spectral sensitivity maximum to significantly longer wavelengths in both age-classes, but a distinct secondary short wavelength peak is visible only in the younger instars. These shifts appear to be due to the presence of migrating screening pigments, which are probably vestigial in the deep-living adults. Anomalies in the response waveforms under chromatic adaptation also apparently result from filtering by screening pigments, but via an unknown mechanism.

The mean weight in sea water of specimens of the electric ray, Torpedo nobiliana Bonaarte, was only 0·4 % of the weight in air compared with 4·4 % in other bottom-living rays. T. nobiliana was so buoyant because it had large livers (up to 20% by weight) containing a lot (up to 70 %) of oil of low density (0·91 g/cm3) and because some of the body tissues were less dense than in other rays.

Specific rations for the zooxanthellae-bearing medusa, Linuche unguiculata, were calculated using two approaches: (a) gut contents of field collected medusae combined with experimental measurements of digestion time; and (b) experimental feeding studies combined with estimates of ambient prey biomass. Estimates of specific daily ration from gut contents averaged 5% for carbon, 6% for nitrogen, and 4% for phosphorus for the dominant size of medusae. Of the 868 medusae examined, 86% contained recognizable prey with an average of 3.6 items per medusa. Copepods dominated the gut contents (51%) as well as the ambient zooplankton prey (82%), but there was an over-representation of shelled prey, larval molluscs and foraminifera, in the gut (33%) compared with their availability (4%). Digestion times for crustaceans ranged from 1—4 h with longer times for larger prey. Ambient prey concentrations in areas of abundant L. unguiculata ranged from 0.2—4.0 prey l-1, with an average of 1.7 and no measurable day—night differences. There were also no measurable day—night differences in ingestion rates for field or laboratory fed medusae. Feeding studies showed a linear relationship between ingestion and prey concentration up to 400 prey l-1. Rations determined from experimental feeding studies were higher but less than double the ration estimates based on field gut contents. Specific ration decreased with increased medusa size in both field and laboratory results. Heterotrophy was calculated to be a major source of both nitrogen and phosphorus, but only a minor source of carbon. Elemental budgets for carbon, nitrogen and phosphorus were calculated using measured inputs of photosynthesis, ingestion, and dissolved nutrients and measured outputs of respiration, excretion, reproduction and tissue growth. Total measured outputs balanced the inputs, within the uncertainty associated with egg production.

The muscle fibres of the radial muscles of the unpaired fins of dogfish can be divided into two populations—an outer group of red muscle fibres which are smaller and fewer than the inner white muscle fibres and which differ in structure, number of nuclei and pattern of innervation. Two types of potential were detected in the two muscle systems when recordings were made with implanted electrodes during movements of the fins. The red muscle fibres were associated with small, slow junctional potentials which changed in amplitude when the activity of the system was altered.

An oceanographic cruise conducted during June 2008 in the Gulf of Gabes revealed the existence of different water masses; the Modified Atlantic Waters (MAW) circulated in the upper 100 m in the offshore area, the Mixed Mediterranean Water (MMW) was confined to the inshore region and the Ionian Water (IW) was in deep offshore water. The thermal stratification was indicated by the vertical profiles of temperature generated from a coast-offshore section. Phosphorus limitation was induced by the thermal stratification as shown by the high N/P ratio. Heterotrophic and mixotrophic dinoflagellates were the major contributors to total phytoplankton biomass. Ciliates were less abundant and dominated by tintinnids. Small planktonic copepods (≤1.45 mm) contributed to 93.64% of total copepod abundance in the inshore area as a result of the high density of Oithona similis, Oithona nana, Clausocalanus furcatus and Euterpina acutifrons in this area characterized by warm and salty MMW. In fact, small copepods were significantly correlated to both temperature and salinity. Small copepod fraction prevailed also in the MAW contributing to 71.05% of total copepod abundance as a result of the dominance of O. nana and C. furcatus. Nonetheless, the large copepod Nannocalanus minor was more adapted to the deep IW where it contributed to 44.05% of total copepod abundance. Invasive species were encountered in the offshore region intruded by the Atlantic waters. The Atlantic copepods were scarce and less abundant reflecting the weakening of the Atlantic flow in the eastern basin of the Mediterranean.

Pionosyllis Malmgren, 1867 is revised based on a cladistic analysis of the 41 species considered herein as valid, two newly described species in this paper (Basidiosyllis victoriae and Opisthodonta russelli), 11 species from other genera actually belonging, or related to, Pionosyllis, and 13 syllid species from different subfamilies. The phylogenetic analysis is based on 55 characters; a strict consensus of 1200 equally parsimonious trees (length = 314 steps) was obtained. The clades containing species usually included within Pionosyllis are newly named within the frame of a new Linnean classification of the group (except for one, belonging to another subfamily). The diagnosis of Pionosyllis is emended, and five new genera are proposed: Synmerosyllis, Basidiosyllis, Westheidesyllis, Perkinsyllis and Brevicirrosyllis. Paraehlersia San Martín, 2003, proved to be closely related to Pionosyllis. Seven species are transferred to Opisthodonta Langerhans, 1879, here emended, and three transferred to Nudisyllis Knox & Cameron, 1970 (according to San Martín & Hutchings, 2006). Opisthodonta uraga (Imajima, 1966) comb. nov. and Perkinsyllis longisetosa comb. nov. are redescribed. Pionosyllis compacta Malmgren, 1867, P. stylifera Ehlers, 1913, P. gigantea Moore, 1908, P. enigmatica (Wesenberg-Lund, 1950), and Nudisyllis magnidens (Day, 1953) comb. nov., are redescribed. Pionosyllis marquesensis Monro, 1939 and P. procera Hartman, 1965 likely belong to the Syllinae, thus they are not treated in the taxonomic account.

Sinking of particles was measured at a coastal site near La Coruña (north-western Spain) using sedimentation traps placed at the base of the euphotic zone during four short periods between March and June 1995. In addition, measurements of water column properties and particles were made at five stations. The cases studied were representative of the main oceanographic situations that occur in this area and were related to the wind-induced upwelling. Phytoplankton blooms (> 100 mg chlorophyll−a m−2) were observed on two occasions in April and June, both during favourable upwelling conditions. The two other cases were studied during low phytoplankton biomass concentrations in the water column.

The hypertrophic and much elongated epicranial (nasal) complex of sperm whales (Physeter macrocephalus) is a unique device to increase directionality and source levels of echolocation clicks in aquatic environments. The size and shape of the nasal fat bodies as well as the peculiar organization of the air sac system in the nasal sound generator of sperm whales are in favour of this proposed specialized acoustic function. The morphology of the sperm whale nose, including a ‘connecting acoustic window’ in the case and an anterior ‘terminal acoustic window’ at the rostroventral edge of the junk, supports the ‘bent horn hypothesis’ of sound emission. In contrast to the laryngeal mechanism described for dolphins and porpoises, sperm whales may drive the initial pulse generation process with air pressurized by nasal muscles associated with the right nasal passage (right nasal passage muscle, maxillonasolabialis muscle). This can be interpreted as an adaptation to deep-diving and high hydrostatic pressures constraining pneumatic phonation. Comparison of nasal structures in sperm whales and other toothed whales reveals that the existing air sac system as well as the fat bodies and the musculature have the same topographical relations and thus may be homologous in all toothed whales (Odontoceti). This implies that the nasal sound generating system evolved only once during toothed whale evolution and, more specifically, that the unique hypertrophied nasal complex was a main driving force in the evolution of the sperm whale taxon.

Statolith microstructure was studied in 162 specimens of Illex coindetii (mantle length ranging from 48 to 300 mm) captured on the shelves of Sierra Leone and Western Sahara between May and November 1987. Growth increments were revealed in all statoliths studied, but they were not well-resolved as in other congeneric species Illex illecebrosus and Illex argentinus. Age and growth rates were estimated assuming that growth increments within statoliths were produced. In both regions, differences in growth rates between sexes (females become larger than males) occurred first in length and then in weight. Geographical differences in sex-specific growth (Western Sahara squid grow faster and attain larger sizes than Sierra Leone squid) was apparent after 150 d in females and 120 d in males. Illex coindetii in Sierra Leone started maturing at smaller sizes but at approximately the same age as the Western Sahara squid. Small sized early maturing groups of I. coindetii with a life span of ~0.5 y occurred in both regions. However, large sized late maturing squid with a life span of ~1 y were encountered only in the Western Sahara. In waters of the west African shelf, I. coindetii spawn throughout the year.

Regeneration of ectoderm and mesogloea, and the interactions of these layers, in the sea anemone Calliactis parasitica (Couch) have been studied by examining the healing of simple wounds. Studies included the part played by the mesogloeal cells, the origin and functions of which have been much debated.

The presence of two dinoflagellate species of the genus Asterodinium, which are a priori representative of warm waters, is reported for the first time in the western Mediterranean Sea. Asterodinium libanum was identified in the Bay of Villefranche-sur-Mer (Ligurian Sea), while Asterodinium gracile is reported in the Tyrrhenian Sea. These findings are discussed in the context of the progressive warming of Mediterranean waters.

Morphometric and gonad maturity of Libinia spinosa on the coast of Mar del Plata, Argentina, were assessed. In both sexes various morphometric features were measured to determine the morphometric maturity, and through macroscopic inspection of gonads and analysis of its content, different stages of gonad maturity were described and the physiological maturity was estimated. In females, the carapace width ranged from 8 to 56.5 mm while in males from 4.6 to 81.97 mm. The size at which 50% of females were morphometrically mature was calculated at 40.6 mm. Based on the allometric growth of the abdomen, two morphometric groups of females were recognized as juvenile and adult phases. In males, results of principal component analysis showed that the most suitable variables that efficiently represent the size and sexual differentiation factor were the carapace width and cheliped length respectively. The size at which 50% of males were morphometrically mature was estimated at 58.9 mm. Based on the allometry of the cheliped growth, two morphometric groups were recognized as immature and mature phases. Males maintained under laboratory conditions moulted and growth was related to regular and terminal moults. Males reached their terminal moult at a wide size-range, from 48.5 mm to 61.4 mm of carapace width. This terminal moult coincided with the size of morphometric maturity. In both sexes four stages of gonad development were described, two corresponded to immature phases and two to mature phases. The size at which 50% of females and males reached gonad maturity was LC50 = 40.33 mm and LC50 = 33.6 mm, respectively. In females, both morphometric and gonad maturity occurred at a similar size. In males, gonad maturity is acquired prior to morphometric maturity, thus three different types of males were characterized: (1) those with small carapace width and cheliped, without spermatophores in their vas deferens; (2) those with large carapace width and small cheliped, bearing spermatophores in their vas deferens; and (3) those with large carapace width and cheliped, bearing spermatophores in their vas deferens.