Noctiluca miliaris Suriray is a well-known luminescent organism, and its light emission has been studied repeatedly. Hitherto, however, no attempt has been made to record the luminescent flashes of this species, either under normal conditions, or after experimental treatment. With the sensitive photo-electric recording methods now available it has become possible to subject the luminescent flashes of Noctiluca to experimental analysis, and with this end in view the present study of Noctiluca was undertaken.

Pennatula phosphorea Linn, is a well-known luminescent animal, which was studied by that pioneer investigator, Panceri (1871,1872 a, b). He found that the animal luminesces when excited, and that the light emanates from the zooids. From the region stimulated luminous waves proceed, with measurable velocity, to the extremities of the animal. Since waves can be initiated in either direction, up or down the colony, it follows that the transmission system is non-polarized. Recent studies on other species of pennatulids have shown that luminescence is under control of a nerve net (Nicol, 1955 a, b, c; Daven-port & Nicol, 1956). Harvey's book on Bioluminescence (1952) gives a review of pertinent literature, plus a bibliography.

In a previous paper (Hancock, 1955) an account was given of the feeding behaviour of the starfish Asterias rubens L. and the common sunstar Solaster papposus (L.) on Essex oyster beds. In discussion, it was stated that there was no evidence that, in the conditions described, a cultivated oyster ground provided a greater attraction than an uncultivated one. The present work was undertaken to provide information on this subject, and also on the movements, growth and ecological relationships of starfish. Further experiments were made on feeding behaviour, particularly of the young starfish.

Although the biology of the oyster Ostrea edults has been well studied, its growth has received little attention. Orton (1928) worked on the populations in the Rivers Fal and Blackwater, but his conclusions have not been supported by Havinga (1928) or Korringa (1955), while America studies on Crassostrea virginica have given further evidence of the need for new investigations.

A knowledge of growth rates is a pre-requisite in estimating the effect of fishing upon the available stocks. In Crustacea, where there is no known means of establishing accurately the age of the individual, the importance of measuring the growth rate is increased whilst its determination is made more difficult. In Homarus vulgaris some experiments were undertaken by Dannevig (1936), and Wilder (1953) gives considerable data for the American lobster. Results suggest that the growth increment is not uniform in all latitudes. Experiments to augment the limited data available for H. vulgaris and to establish the increase in size at moulting in local lobster stocks were therefore undertaken by the Marine Laboratory of the Scottish Home Department at Aberdeen. A statement of some preliminary results was given in Report on the Fisheries of Scotland (Lucas, 1957, p. 58).

Little is known about the occurrence of gallium in the biosphere. The first recorded instance of its detection in a living organism is due to Cornec (1919), who detected the element in Laminaria sp. Vinogradov (1935) suspected its presence in an undetermined gorgonian, but his statement that Zvinden had detected it in human tissue appears to be an erroneous citation (Hutchinson, 1943). Bertrand (1941) detected the element in oysters, and, after chemical concentration, in human urine.

Three species of the polychaete genus Magelona are known from the neighbour-hood of Plymouth. One is the widely distributed M. papillicornis F. Müller, described first from the coast of Brazil (Müller, 1858) and subsequently frequently recorded for northern European coasts and the Mediterranean. Near Plymouth this species occurs in clean sand in the lower tidal region and offshore, as in Whitsand Bay. Of the other two species, one from clean sand near low water at Mill Bay, Salcombe, awaits description. The third has been known for many years but until now has not been recognized as an undescribed species. It was formerly abundant in the Rame Mud (a deposit of black sandy mud); thus Mare (1942, p. 542, as M. cincta Ehlers—a provisional identification by me) on 12 July 1939 found 120 per m, associated with large numbers of other polychaetes, lamellibranchs, etc. The locality was close to Ford's station No. 93 (Ford, 1923, chart facing p. 167, and p. 218 where the position is given as Rame Head, E. ½ N. Tregantle, N.½ E.). At this station on 20 February 1923 Ford had four specimens (recorded as M. papillicornis) from ⅕ m. On 11 August 1922 at station No. 53 close by (Rame Head, E., 1½ miles) he obtained thirteen specimens of the same species from 1/10 m, the substratum being black mud. Ford records papillicornis from other offshore mud or muddy-sand stations over a fairly wide area inside and outside Plymouth Sound, but in less abundance. It is certain that some of these records, especially those detailed above, are of the species taken by Mare and provisionally identified as cincta.

In the course of dredging for the rich epifauna of the continental slope near 48° 30′N., 10° W. (Southward & Southward, 1958b) in May 1957, several hauls were made by chance on a muddy bottom at 500–700 fin. depth. At the time, these hauls were examined only cursorily after sieving, and the con-tents immediately preserved. One of the hauls contained several damaged siliceous sponges, and a recent careful examination disclosed a number of pogonophore tubes entangled among the threads and spicules of the sponges.

The fauna of the continental shelf and slope between Ireland and Spain has been described by Le Danois (1948), but very little faunistic work has been carried out in the area recently. Since R.V. ‘Sarsia’ was brought into service at Plymouth there have been several opportunities of investigating that part of the slope lying to the south-west of the British Isles. It has been found that, in addition to beds of coral, quite extensive exposures of rocks, stones and gravel occur between 200 and 1000 fathoms. There is a rich epifauna in this area and barnacles are one of the dominant groups.

In previous papers (Millar, 1952; 1954a; 1954*0 I have dealt with the re-productive cycle of several ascidians in Scottish waters, and in the present account observations are extended to other species.

The course of breeding was studied in the following species. Family Polyclinidae:Sidnyum turbinatum Savigny, Aplidium nordmanni (Milne Edwards), A.punctum (Giard), A.pallidum (Verrill) and Polyclinum aurantium Milne Edwards. Family Didemnidae:Didemnum candidum Savigny and Lissoclinum argyllense Millar. Family Clavelinidae: Clavelina lepadiformis (Müller).

An important fishery for the scallop, Pecten maximus (L.), is carried on during the winter months round the Isle of Man. A knowledge of the breeding of this lamellibranch would be useful should legislation become necessary with regard to the fishery.

Regular samples of scallops were dredged, whenever possible, at roughly weekly or fortnightly intervals throughout the period October 1950-October 1952, from a depth of 13–16 fm. off Bradda Head and Bay Fine, near Port Erin. Approximately 8000 scallops of all ages up to 13 years were examined, though very few young ones were caught. Scallops were aged by means of the growth-rings on the shell, of which one is laid down each spring (Mason, 1957).

The vitamin B12 concentration in sea water is so very low that only the most sensitive microbiological assay techniques are likely to be capable of measuring it, but the salt concentration is so high as to be inhibitory to most of the organisms conventionally used for the microbiological assay of the vitamin. Nevertheless, the consideration that vitamin B12 concentration may have an influence on the amounts and types of life present in sea areas has persuaded several investigators to attempt its measurement.

The methods so far employed have each their own advantages and dis-advantages (Droop, 1954, 1955; Lewin, 1954; Sweeney, 1954; Cowey, 1956; Adair & Vishniac, 1958). The method to be described here offers advantages in sensitivity, permitting direct measurement of the vitamin in small quantities of oceanic waters after further dilution; samples to be measured pass through comparatively few different containers and thus there is less risk of their accumulating adventitious vitamin; simple and easily cleaned apparatus is used, and much less bench-work is involved than when methods other than dilution are used for lowering the salt concentration.

A considerable seasonal variation in the vitamin B12 concentration in oceanic surface water has been demonstrated by Cowey (1956).

The present investigation was undertaken to examine any variation with depth.

In recent years much information has accumulated on the composition and distribution of algal populations in the Isle of Man, with increased knowledge of their ecological relationships (Knight & Parke, 1931, 1950; Jones, 1948; Lodge, 1948,1954; Burrows & Lodge, 1949, 1951; Southward, 1953). This, however, has mostly come from studies made in the intertidal region, and even here many problems remain for which, at present, no satisfactory explanation can be found. The mostdimcult of these, perhaps, relates to the appearance of algal species for a limited period of the year only: it is not known where and in what form their life-histories are continued for the rest of the year. The littoral and sublittoral regions are known to have many species in common. This means that the differences between the regions, as environments for the growth of algae, can be bridged by the plasticity of the species concerned. It seemed likely, therefore, that a detailed study of the sublittoral algal populations might help towards an understanding of the ecology of both regions and also of the interactions between them.

Luminescence is very common among marine animals, and many species possess highly developed photophores or light-emitting organs. It is probable, therefore, that luminescence plays an important part in the economy of their lives. A few determinations of the spectral composition and intensity of light emitted by marine animals are available (Coblentz & Hughes, 1926; Eymers & van Schouwenburg, 1937; Clarke & Backus, 1956; Kampa & Boden, 1957; Nicol, 1957b, c, 1958a, b). More data of this kind are desirable in order to estimate the visual efficiency of luminescence, distances at which luminescence can be perceived, the contribution it makes to general back-ground illumination, etc. With such information it should be possible to discuss more profitably such biological problems as the role of luminescence in intraspecific signalling, sex recognition, swarming, and attraction or repulsion between species. As a contribution to this field I have measured the intensities of light emitted by some pelagic species of animals.

The upper reaches of the deep ocean contain many bathypelagic fishes with a capacious, gas-filled swimbladder. But living within and below this region are also numerous species in which this hydrostatic organ is absent or markedly regressed (Marshall, in preparation). In the neritic province nearly all the fishes that swim freely at the various water levels (and can stay poised at a particular level without undue effort) have a well-developed swimbladder, the capacity of which is about equal to 5 % of the body volume (Jones & Marshall, 1953). Having this amount of gas, these fishes are able to keep their weight in water close to the vanishing point. If such a fish were deprived of its swimbladder, it could keep at a constant level only by exerting a down-ward force equivalent to 5 % of its weight in air. The swimbladder thus saves the fish the energy needed for such effort, which is quite appreciable.

As a result of the geological formation of the Isle of Wight there is a great variety in the type of shore. Although much of the coastline is unsuitable for the establishment of algal communities there are some parts where a few species can exist, and others where full zonation is achieved. It therefore seemed worth making some study of the algal distribution. Towards this end a general survey was made of the south coast of the island in April 1955, with more detailed studies of the places of interest by means of transects in April and July 1955.

A good deal is known about the growth in culture of Phaeodactylum tricornutum Bohlin (Nitzschia closterium W. Sm. forma minutissima Allen & Nelson) (see Spencer, 1954; Harvey, 1955; Provasoli, McLaughlin & Droop, 1957). This organism, however, is a somewhat aberrant member of the Chrysophyta, and other marine and brackish-water representatives of the group, e.g. Syracosphaera carterae Braarud & Fagerland (Braarud & Fagerland, 1946; Provasoli, McLaughlin & Pintner, 1954), Prymnesium parvum Carter (Reich & Kahn, 1954; Droop, 1954), and certain other species (Droop, 1954, 1955 a, b) have been studied much less intensively from this point of view. It has therefore seemed worth while making a general study, similar to that reported in the first paper of this series for the diatom Asterionella japonica Cleve & Müller ex Gran, of the growth requirements of a representative of the Chrysophyceae. Isochrysis galbana Parke, a flagellate of some importance as a food organism of the oyster, has been selected for this purpose. Johnston (1955) has used unialgal cultures of this species in studies of dissolved organic matter in sea water and, since the investigation being described was carried out, Droop (1957) has reported that it has a requirement for cobalamin.

In a recent study (Ross, 1957) isolated marginal sphincter preparations of the sea anemone, Calliactis parasitica, showed two distinct responses to stimulation: (1) a quick contraction in response to stimuli at frequencies from 0–2 to 3–0 sec, the facilitated response of Pantin (1935 a) beginning only on the second stimulus of a series, with a latent period of about 0 1 sec; (2) a smooth slow contraction in response to stimuli at lower frequencies, with a latent period of not less than 30 sec, and beginning only after several stimuli. This slow movement of the marginal region had not been detected in work on whole animals, but it is similar to the contractions of the ‘slow’ muscles of Calliactis (Pantin, 1935 b) and Metridium (Batham & Pantin, 1950 a). However, Calliactis sphincter shows almost no spontaneous activity.

Both quick and slow contractions had previously been observed in excised sphincters and mesenteric retractors of Metridium (Batham & Pantin, 1954), the chief muscles utilized in the closure of that animal. In all these cases, the quick contraction would seem to be a specialized mechanism for sudden withdrawal superimposed upon, and perhaps developed from, a more primitive and general slow contractile mechanism. As part of a programme to investigate and compare the properties of quick and slow contractions in these muscles it seemed desirable to see what part, if any, slow contractions of the marginal sphincter play in the life of Calliactis. This involved us in a wider study of the neuromuscular activity of this anemone which normally lives on shells inhabited by the hermit crab, Eupagurus bernhardus.