William Ringrose Gelston Atkins was appointed Head of the Department of General Physiology at the Plymouth Laboratory in February 1921 at the age of 36 having already at Trinity College, Dublin, applied widely the methods of physics and chemistry to the problems of biology, particularly botany. He was very well equipped to study the physics and chemistry of sea water as an environment for marine life. He served with great distinction at Plymouth, apart from the years of the Second World War, until he retired from the staff in March 1955 and enjoyed only four years of leisure before his death on 4 April 1959.

By the death at the age of 84 of Mr William H. Searle there passed away, on 6 April i960, one who had served the Laboratory longer than anyone else and who, during his 63 years as fisherman-collector, had installed himself in the affections of countless biologists the world over. From December 1895 until his retirement on 30 September 1958 his assiduous and unwearied devotion to his collecting duties, year in and year out whatever the weather, on the shore or in his boats, earned him the lasting gratitude of all those innumerable research workers, teachers and students who relied on ‘Bill’ to procure living material for their researches or studies. He, more than anyone else, knew where the animals were to be found, how to capture them without damage and how to ensure their safe arrival at the Laboratory hours later. More than one student who had been collecting on the shore alongside Bill has later been astonished to observe the large and varied assortment of creatures emerging alive and kicking from one small and tightly packed basket. He had a keen eye for the little things—Gromia, praniza larvae and the like, from the rock crevices he split open with his crow-bar. These he would carefully transfer from silted rock surface to honey jar on the point of his pocket-knife. He knew well their scientific names, though foreigners would often have difficulty in recognizing them when pronounced with a strong Devonshire accent. It was usually the old names current during his youth that he knew, and he was not alone in deploring the activities of systematists in so frequently changing and re-changing so many of them.

Twenty years ago the Plymouth Laboratory investigated the spawning of mackerel and pilchard in the Celtic Sea. The physical background for their work, which the late Dr G. A. Steven and Mr P. G. Corbin sought, could not be provided since waters with similar temperatures and salinities evidently had very different physical and biological histories.

Lasaea rubra, like other small Erycinacea, is unusual among eulamellibranchs in its relatively great mobility on the surface of the substrate. It can crawl about as freely as a small gastropod and lays down a mucous trail for the attachment of its progressing foot, drawing the shell and body rhythmically forward after each advance thrust of the foot. Unlike some other Erycinacea, L. rubra has no well-defined sole; it attaches by the sharp lower edge and part of the side of the foot, which is strongly ciliated and well supplied with mucous glands. In most burrowing eulamellibranchs, the site of communication with the surrounding water has shifted to the paired siphons at the posterior end. The Erycinacea, however, have an anterior inhalant siphon; and—as in forward moving prosobranch gastropods (Morton, 1958)—there is an obvious adaptive advantage in receiving the ingoing current from the water into which the animal is moving.

Nerve cells evidently of a sensory nature have been found in Eledone cirrhosa on the inside of the mantle in a limited area near the stellate ganglion. The cells, whose number on each side of the body is no less than 50, are in close association with a special thin layer of muscles, and obviously must have a proprioceptive function. The whole complex can therefore be regarded as a muscle receptor which from its situation may be termed the substellar organ.

The muscular component of this organ consists of fibres arranged in very flat bundles which, anastomosing with one another, form a plexiform layer situated under the stellate ganglion and the stellar nerves. It may be called substellar muscle plexus (ss-plexus for short). The area occupied by it, which is roughly semicircular in shape, extends to the points where the stellar nerves penetrate the muscles or a little beyond these points (Text-fig. 1). The ss-plexus, although situated close to thecompact muscle of the mantle, does not appear to have anatomical relation with the latter; it has, however, direct connexions with strands of muscle fibres reaching theplexus from two directions. The fibres coming from the medianside belong to the muscle attaching the mantle to the visceral sac in which runs the pallial nerve (or mantle connective). This muscle, called lateral pallial adductor (see Tippmar, 1913) istwisted in such a way that its bundles coming from the anterior region of the visceral sac insert into the mantle behind the stellate ganglion, and those originating posteriorly insert in front of it.

Studies by many workers on the subtle ecological relationships of marine organisms suggest that the distribution of these organisms may be controlled, at least in part, by trace organic substances in their environment. These substances may range from ‘toxins to vitamins and hormones’ (Lucas, 1955). Saunders (1957) has reviewed the interrelations ofdissolved organic matter and phytoplankton and considered the possible roles of organic metabolites in the growth of the algae. The presence of several vitamins, for example, B12, thiamin, niacin and biotin, has been demonstrated in natural waters, but the possible occurrence of plant hormones has not previously been considered.

Relative spectral emission curves are available for the lights of many invertebrate animals, but none exists for fish. It seems likely that many bony fish use their photophores to signal to one another. Information about the spectral composition of fish luminescence is desirable to permit comparisons with the spectral sensitivities of fish eyes, to enable calculations to be made of luminous intensities, and to allow estimates to be made of the rate of attenuation of such lights in sea water. To further these ends, measurements were made of the spectral composition of the luminescence of the lantern-fish, Myctophum punctatum.

The physical oceanography of the shallow seas south-west of the British Isles ismuch influenced by the exchanges of waters around headlands between neighbouring areas of the sea. These are

In a recent paper (Allen, 1958) the ligament of Cochlodesma praetenue (Pulteney) as shown to have unusual features, the significance of which was not appreciated at that time. Examination of its structure shows that a further description is necessary.

Studies by Owen, Trueman & Yonge (1953), Owen (1958,1959), and Yonge (1953, 1957) have made clear the basic structure of the ligament of the adult bivalve. Primarily the ligament is composed of an inner layer covered by the anterior andposterior outer layers and the periostracum. The inner layer is secreted by the epithelium of the mantle isthmus, the outer layers are secreted by the outer surface of the outer mantle fold within the depths of the mantle embayments at either end of the mantle isthmus, and the periostracum is secreted by the inner surface of the outer mantle fold. This primary ligament may be secondarily extended anteriorly and/or posteriorly by fusion of the mantle margins and may involve extension by periostracum, or extension by fusion layer.

For a third of a century many and varied studies on sea water have been concentrated upon a single accessible shallow-water station in the English Channel, EI, supplemented by more extensive excursions usually designed to test working hypotheses. This concentration of effort has been richly rewarded. In deep-water oceanography a similar approach is appropriate; a standard station, ‘Cavall’ has therefore been selected in the north-eastern Bay of Biscay in 4700 m of water at lat. 46° 30' N., long. 8° 00' W., nominal, a position worked by the Danish Research Vessel ‘Dana’ in 1922 and 1930. It is not only the nearest deep water position to Plymouth but it has best possible coverage by the Decca Navigator system. For our experimental programme it is essential that the station positions be maintained and repeated precisely. To achieve this a working Decca chartlet (Fig. 1) on a scale of 1:20,000 has been prepared for each station from a portion of the Admiralty Decca Lattice chart no. L 1104. On this a circle of radius one mile is inscribed. Throughout operations the ship is maintained within this circle by stopping work when necessary and steaming back on Decca co-ordinates towards the centre, or beyond to pre-compensate expected drift.

The last of the organisms to be studied in this series was chosen as a representative of the Dinophyceae. The treatment of Prorocentrum micans Ehrenberg has been similar to that of Asterionellajaponica Cleve & Müler ex Gran (Kain & Fogg, 1958 a) and Isochrysis galbana Parke (Kain & Fogg, 1958 b). The present paper includes a discussion of the results for all three organisms in the light of work by previous authors.

The vertical distribution of chlorophyll in the sea generally shows a maximum concentration at a depth which may vary from at or just below the surface, to near or below the bottom of the euphoric zone. The easiest distributions to explain are those where the maximum chlorophyll concentration is at or very near the surface. These are found when a population is photosynthesizing actively during the first stages of an outburst, and the distribution corresponds roughly with the change with depth of the photosynthetic rate (Steele, 1957). However, these form a small proportion of observations, probably because outbursts are usually restricted to comparatively short periods of time. The more usual distributions show a maximum in the chlorophyll concentrations well below the surface and below the depth of maximum photosynthesis.

In a series of papers dealing with changes in the distribution of intertidal animals around Britain, and especially along the English Channel, attention was drawn to some local aspects of the general warming-up of sea and air that has taken place in the last 50 years (Southward & Crisp, 1954, 1956; Crisp and Southward, 1958). In the first of these papers smoothed values of annual mean air temperature at Plymouth Hoe, and sea surface temperature of the southern Celtic Sea were given, the latter values being based on Smed (1952). The graphs showed a rise of about 1° C in the air temperature and 0·5° C in sea temperature during 50 years.

The widespread occurrence of sulphatases in the Mollusca was first demonstrated by Soda & Hattori (1933 a, b) who showed that these enzymes are mainly concentrated in the digestive glands. That extracts from marine molluscs also possess β-glucuronidase activity was first noted by Dodgson, Lewis & Spencer (1952) who studied the optimum conditions for the activity of this enzyme and arylsulphatase in Patella vulgata (L.) and Littorina littorea (L.) and applied their findings in an investigation of the distribution of both enzymes among various other marine molluscs (Dodgson, Lewis & Spencer, 1953).

Mites of the family Halacaridae are abundant on the sea shore, and in the sea down to considerable depths. Their identification is not an easy matter; there is no one account which can be used to identify all the British species, and the use of any one of the general accounts of European species, such as André (1946) or Viets (1936), by itself might easily lead to misidentification.

The purpose of the present list is to record the species which have so far been found around the British Isles, and to indicate sources of reliable descriptions of each species. A list of the British species of this family was given in a general list of British Acari by Turk (1953), and this has provided the starting point for the present list; no reference to occurrence in Britain before Turk's list is given, apart from one by Halbert (1920) which was left out by Turk. Twelve of the thirty-six species in the present list were not recorded by Turk. One species, Halacarus zosterae (Fab.), recorded by Turk has been omitted because the original description is quite inadequate to decide even which genus the creature should belong to. Eight species are known from British fresh water; these have not been included in the present list.

The Megathyridae Allan 1940 is a family of brachiopods in which the adult lophophore is of simple design, bilobed (schizolophous) in Argyrotheca and four-lobed (ptycholophous) inMegathyris. Little is known of feeding mechanisms in the family. H´erouard (1877), finding it difficult or impossible to observe the feeding currents of living brachiopods, constructed artificial lophophores of lead piping with fine perforations corresponding to the position of attachment of the filaments. Through these he forced water, while the artificial lophophores were immersed in a bowl of water. He assumed, wrongly, that the result would be similar to the action produced by cilia vibrating in water. His remarks on the working of an artificial lophophore resembling that ofMegathyris (=Argiope) were transcribed by Morgan (1883) without making it clear that the observations were not his own and were not made on the living animal. Apart from HÉerouard's work on artificial lophophores, the only reference to feeding in a member of the Megathyridae is that of Shipley (1883) who merely mentioned that inArgyrotheca the arrangement of the cilia is adapted to bring particles into the ciliated groove and thence to the mouth. Thus an examination of the method of feeding of the Megathyridae was considered desirable, and was made possible in the first instance through the kindness of M. Paul Bourgis, then, in 1955, on the staff of the Laboratoire Arago, Banyuls-surMer. He sent two small consignments of livingArgyrotheca cor data (Risso),A. cuneata (Risso) andMegathyris detruncata (Gmelin), received on the 28 October and 24 December 1955.

As modern instrumentation improves the precision of the measurements of underwater light, particularly of monochromatic light, both biological and physical oceanographers are becoming increasingly interested in such measurements in deep water

Since November 1954, the natant epifauna in depths greater than 20 fm. off the Northumberland coast has been sampled at a number of stations with the object of obtaining information on its constitution and fluctuations. The survey has been limited to those species caught with a net of f in. mesh. Seasonal and yearly fluctuations in this fauna must have a considerable effect on the inshore fisheries, for these animals form an important part of the food of marketable fish, yet, this fauna has never beensubject to a detailed analysis over a number of years.

Samples have been taken as regularly as weather and other laboratory commitments have allowed. In practice this has been of the order of one sample each month, butat times sampling has been more frequent than this (Table 8). Although sampling is being continued, the material collected so far gives much information on the epifaunaas a whole and the biology of the constituent natant Crustacea and Mollusca.

There have been few analyses of the fat, protein and carbohydrate fractions in zooplankton, and owing to the difficulty of sorting large numbers of single species, the majority of the earlier determinations were necessarily carried out on mixed zooplankton hauls (Brandt, 1898; Brandt & Raben, 1919; Moberg, 1926; Wimpenny, 1929; Drummond & Gunther, 1934; Vinogradov, 1953). Most of these analyses suggested a relatively high protein and fat content, and this was confirmed by Orr (1934 a), who investigated the chemical composition of a single species, Calanus finmarchicus. Orr's result gave fat, protein and chitin as 20–40,35–50 and 3%, respectively of dry weight. Similar high values were also reported by Orr (1934 b) for Euchaeta norvegica. The carbohydrate content was not, however, estimated in either of Orr's investigations since large numbers of animals would have been required. Brandt (1898), after analysing mixed plankton hauls which were predominantly copepods, suggested a carbohydrate content of ca. 20%.