When stimulated in some suitable manner Chaetopterus secretes a luminescent material into the surrounding sea water. The luminescent secretion is discharged fromglands which are widely dispersed over the surface of the animal; the most conspicuous are two glandular patches on the dorsal surface of segment XII. Secretory materialis forced out of the cells by some contractile process; discharge is not merely theresult of secretion pressure. Under repetitive stimulation the intensity of the luminescent response decreases owing to the intervention of fatigue. Fatigue has been interpreted as a gradual exhaustion of luminescent material in the glandular cells (Nicol, 1952b,c).The present investigation seeks to analyse the onset and progress of fatigue in greater detail.

A marine fungus, Plectospira dubia n.sp., has been found infecting crustacean eggs and small Crustacea in the Plymouth Laboratory. It has the following characteristics: mycelium mostly intra-matrical, coarse, hyphae 50–100µ in diameter. Sporangia irregularly inflated, emptying by efferent hyphae of variable length and frequently of irregular diameter; sometimes proliferous; wall persistent. Zoospores dicystic and dimorphic, but the first swimming stage largely suppressed, the first zoospores mostly encysting within the sporangium after a short period of feeble activity, then swimming in the second stage. The first zoospores pyriform and flagellate (probably biflagellate): in the second motile stage laterally grooved with two laterally inserted flagella. First zoospores about 1oµ long, when encysted 7–8µ in diameter; in the second motile stage 11–12µ long, when encysted 6–7µ. in diameter. Gemmae numerous, spherical, up to 1OOµ. in diameter. Sexual organs so far unknown.

The main picture of the zonation of life between tide marks on British shores has been added to by a good deal of recent work, such as that of Colman (1932) and Evans (1947) at Plymouth, and the regional studies by Stephenson & Stephenson (1949). Of the more restricted special habitats within the tidal area there have been fewer accounts, though Colman (1940) has made a detailed survey of the faunas inhabiting intertidal seaweeds, which was later followed by Wieser (1952). Most recently there has appeared a paper by Glynne-Williams & Hobart (1952), working at Anglesey, which for the first time analysed clearly the composition and food relations of the restricted fauna living in crevices in this habitat. This part of the tidal zone forms an interesting meeting place of two faunal elements, those intertidal animals of terrestrial origin and those which are truly marine. In the summer of 1950 and 1951 the present writer had made a similar study in the Plymouth area, at Wembury and some other localities. The work was begun as part of an ecological study of the two marine pulmonates Leucophytia bidentata and Otina otis, and was later extended to take account of the other animals hidden in crevices and those living on the exposed rock surface throughout the upper half of the tidal zone.

The survey of the sublittoral fauna of the Clyde Sea Area from 1949 onwards has shown that five species of the Protobranchiata are abundant throughout this region on a variety of substrata. Pelseneer (1891, 1899, 1911), Heath (1937), and Yonge (1939) have contributed much to the knowledge of the group as a whole, but little comparative work has been done at species level. Verrill & Bush (1897, 1898) studied the shell characters of the American Atlantic species. Moore (1931 a, b) worked on the faecal pellets of the British Nuculidae and attempted to distinguish the species by this means, while Winckworth (1930,1931), mainly in the light of the latter work, attempted to clarify the nomenclature of these species. Winckworth (1932) lists six British species of the family Nuculidae: Nucula sulcata Bronn, N. nucleus (Linné), N. hanleyi Winckworth, N. turgida Leckenby & Marshall, N. moorei Winckworth and N. tenuis (Montagu); and four species of the family Nuculanidae: Nuculana minuta (Müller), Yoldiella lucida (Loven), Y. tomlini Winckworth and Phaseolus pusillus (Jeffreys). All species of Nucula, except N. hanleyi, were taken from the Clyde Sea Area, although the latter species is included in the Clyde fauna list (Scott Elliot, Laurie & Murdoch, 1901). Only Nuculana minuta of the Nuculanidae has been taken on the present survey. Yoldiella tomlini is included in the 1901 list but is noted as being ‘insufficiently attested’. Nucula hanleyi was obtained from the Marine Station, Port Erin, but Yoldiella and Phaseolus were unobtainable.

The urine secretion of the kidneys of Lophius piscatorius perfused with heparinized Lophius blood is very sensitive to perfusion pressure below a critical level, above which it becomes insensitive. The response of the urine flow to pressure takes the form of an exponential curve.

The blood flow through the kidneys, while rising slowly at pressures of about 20–30 mm of water, responds arithmetically to pressure above such levels.

At present it is impossible to make out whether pressure or blood flow has the greatest influence on secretion.

Water secretion in the aglomerular kidney is an active process. The oxygen consumption of the Lophius kidney is unmeasurably low, yet remains a possible factor in secretion.

Balanus porcatus (da Costa) is a widely distributed northern species, being found in the Arctic Ocean as far as 80° N., and in the northernmost extensions of the Atlantic and Pacific Oceans. Its southern limits are closely related to water temperatures. Whereas on the east coast of America, where the Labrador current flows southward, it extends to Long Island (lat. 40° N., see Pilsbury, 1916), on the west European coast it scarcely penetrates the English Channel (lat. 51° N.). It is found in some abundance however in the North Sea, the Skagerrak and Kattegat (Krüger, 1927), the Irish Sea, and off the west coast of Scotland and Ireland. The present survey is probably representative of its breeding habits in regions near the southern limits of its range.

Some preliminary observations on luminescence in polynoid worms have been presented in a previous paper (Nicol, 1953). These animals produce light in scales (elytra) which cover the dorsal surface of the body. The source of the light lies in a layer of unicellular epithelium on the lower surface of the scale. Histologically, this tissue consists of columnar cells (photocytes), characterized by the presence of coarse eosinophilic granules in the cytoplasm. The nervous supply of the elytrum derives from a nerve trunk which ascends the stalk or elytrophore and proceeds to a ganglion in the centre of the scale. From this ganglion nerves radiate peripherally and proceed to the photocytes, and to sensory receptors on the dorsal surface and at the margin of the scale (Bonhomme, 1942).

Spirontocaris lilljeborgii is a dioecious species and no protandrous hermaphrodites have been seen.

The majority of males become sexually mature in the first year (7–9 months). Some of these may die after fertilizing the females and the majority die after fertilizing the females for a second year (18 months old).

Only a small proportion of the females breed in their first year, all breed during their second year and a few appear to live for a third year.

A first-year female lays from 130 to 160 eggs, and the usual output of a second-year female is from 450 to 650 eggs.

Egg laying begins at the end of November and hatching is complete by the end of March.

The total incubation period is about 90 days. Eye pigmentation first appears at about half the incubation period (47 days).

Juveniles can be distinguished as males and females by the shape of their pleopods within 4–6 months of hatching.

For routine sampling of the infauna of the sea bottom an apparatus is required which is simple, easily handled, and which can give samples of consistent volume from different types of bottom and in varying weather conditions.

The Petersen sampler and its modification, the van Veen, are simple and easily handled and give reasonably consistent samples from some types of soil. But on hard ground they are less satisfactory, and in rough weather they tend either to land unevenly on the bottom, thereby taking smaller samples of variable volume, or to release in mid-water with the rolling of the ship, so that no sample is taken.

In a previous paper (Armstrong & Atkins, 1950), 201. samples from International Hydrographic Station England No. 1 (EI), about 10 miles south-west of the Eddystone in the English Channel, were filtered through collodion membranes of 1.09μ average pore diameter (A.P.D.).

Between June 1948 and November 1949 the residue from these surface samples, when dried and ignited, amounted to 0.45–2.77 g/m3 (or parts per million). These deposits consisted of 55–17 % silica, 28–3 % ferric oxide, 20 to under 1 % of alumina, and 70 (or, excluding one high value, 29) to 9 % calcium carbonate. A few determinations of insoluble organic matter gave to 1.15–1.77 p.p.m. when dried at 100° C. Pettersson (1934 b), using the glass niters of Schott (Jena), found 1.4 p.p.m. for the total organic and inorganic matter similarly dried, from surface water in the Gullmar Fjord during the spring outburst.

Little is known of the biochemistry of diatoms, although many workers have reported growth experiments with the unicellular algae of the marine phyto-plankton. Experiments have often been performed without due regard for the appropriate control of physical and chemical conditions. Many reports contain only incomplete data of the growth under a given set of conditions, and it is often impossible to say whether the effects recorded are upon the growth rate, the total crop, or both. Other studies have been reported which included the addition of organic matter to cultures which were only uni-algal and not bacteria-free. At the present time even the mere maintenance of stock cultures of the marine unicellular algae is perforce an empirical matter. Results in replicate cultures often show gross differences in growth that are apparent on inspection by eye alone, and insufficient information is available regarding the nature of these variations in growth to allow the rational development of improved culture media. Due therefore to a lack of suitable techniques, most of the results available are difficult, if not impossible, to interpret in terms of the biochemical activities of the algae.

Increasing interest in the comparative biochemistry of marine algae and protozoa is creating a demand for experimental material in the form of pure, i.e. bacteria-free, cultures. For nutritional and biochemical studies pure cultures are, of course, obligatory; but the number of marine strains available for this sort of work is lamentably small. Indeed, none of the so-called μ flagellates has hitherto been grown in pure culture as far as I know, although there exist pure strains of some of the larger and hardier forms.

During 1950, the Common Octopus (Octopus vulgaris Lamarck) was to be found along the south coast of England in greater numbers than at any time since Garstang (1900) reported on the ‘plague’ on the coasts of Devon and Cornwall in 1899–1900.

In earlier papers (Rees, 1950, 1952) the distribution of the octopus in our northern waters was reviewed, and it was demonstrated that this species is an immigrant which breeds on our south coast only rarely. It reaches these coasts by being brought there as a planktonic larva by the water circulation in the English Channel and by migrations of the adult. The most important factor in controlling the movements of the adult, however, might be expected to be the water temperature in the English Channel—where the species is at the northern limit of its breeding range and might therefore be extremely sensitive to slight changes in temperature.

The present list of diatoms may be considered an extension of the recent check-list of British marine algae by Parke (1953). It includes not only truly marine species, both sessile and planktonic, but also species inhabiting brackish waters with a few fresh-water species that manage to live, though somewhat precariously, in estuarine conditions.

It has been compiled for the following reasons: (1) to indicate the extent of the diatom flora around British coasts, so that comparisons may be made with that of the other countries; (2) to assist workers in the identification of material by indicating the size of any genus known to inhabit our shores; (3) to check the arrival of new entrants to the British flora; and (4) to provide a basis for a more detailed work, now in preparation. The check-list does not presume to lay down finalized decisions on the taxonomic rank ascribed to any organism or to consider the criteria upon which such ranks are based.