George Alexander Steven was born at Freshwick, Caithness, on 13 April 1901. His boyhood was spent among crofter fisherfolk, and fishing and boats were part of his youthful environment. During 1924–28 he studied Zoology in the University of Edinburgh, being Vans Dunlop Scholar in 1926. After graduation he came to Plymouth, first as student probationer and then, a year later in 1929, he was appointed to the permanent staff of the laboratory. In 1931 he was elected a Fellow of the Royal Society of Edinburgh, and in 1952 was awarded the Doctor of Science degree of the University of Edinburgh. After a long illness he died on 7 April 1958 at his home in Yelverton, Devon, leaving a widow and two sons.

Nicothoë astaci is a choniostomatid copepod (Gurney, 1929) parasitic on the gills of the lobster, Homarus vulgaris Milne Edwards. In view of the possible effect of Nicothoë on the lobster, which is of considerable commercial importance in Scotland, a programme of work was instituted on the biology of the parasite.

Nicothoë attaches itself by means of its suctorial mouth to a gill filament of the lobster, and the wall of the filament is pierced by the sharp, styliform mandibles. The host's blood is sucked by means of a muscular gullet leading to the stomach. Nicothoë often occurs in groups, especially near the bases of the gills. The adult parasite is incapable of any movement except a slight lateral displacement of the abdomen and, once attached, probably remains in the same position throughout its life. Little is known of the life cycle, and all individuals so far definitely recognized have been females.

In the course of investigations (1955–8) into the Ammodytidae of the south of the Isle of Man, five species of sand eel were identified: Gymnammodytes semisquamatus (Jourdain, 1879), the Smooth Sand Eel; Ammodytes lanceolatus Lesauvage, 1825, the Greater Sand Eel; A. immaculatus Corbin, 1950; A. tobianus Linnaeus, 1758 ( = A. lancea Cuvier), the Lesser Sand Eel; A. marinus Raitt, 1934.

Five different types of post-larvae were obtained and investigated. Four of these were the post-larvae of the above four Ammodytes species and the fifth type proved to be Gymnammodytes semisquamatus.

MacMunn (1886) extracted a porphyrin from the integument of the starfish Asterias rubens—then known as Uraster rubens—and he considered that this and similar pigments which he had obtained from the slug Arion empiricorum and the coelenterates Flabellum variabile and Fungia symmetrica were identical with the haematoporphyrin of Hoppe-Seyler (1871), which was then the only porphyrin known. Dhéré & Baumeler (1928 a) confirmed the presence of a porphyrin in Arion empiricorum, but did not specify which porphyrin they had found. Kennedy & Vevers (1953), working at the Plymouth Laboratory of the Marine Biological Association, found that the pigment of the integument of Asterias rubens L. was protoporphyrin, and in a further survey of the porphyrins of marine invertebrates (Kennedy & Vevers, 1954), they examined the integuments of two molluscs, Aplysia punctata Cuvier and Duvaucelia plebeia (Johnston), and showed that each contained uroporphyrin I. This pigment was also found by Kennedy & Vevers (1956) to be present in the integument of the tectibranch mollusc Akera bullata (O. F. Müller). The present paper describes the isolation and identification of the po phyrin from the integument of the black garden slug Arion ater (L.). Arion empiricorum was a synonym introduced by Férussac, Férussac & Deshayes (1819–51) to cover the numerous colour and pattern varieties of the slug more generally known as Arion ater. The work appears here since it is a continuation of investigations of mollusc pigments initiated in the Plymouth Laboratory, the results of which have already been published in this Journal.

During the last four years collections of plankton from deep water have been made regularly on the cruises of R.V. ‘Sarsia’. The opportunity has been taken to study the biology of the scyphomedusa Atolla wyvillei. It was hoped that with material collected from the same area at different times of the year it might be possible to gain some information on the growth and length of life of this medusa. The collections have been supplemented by a number of specimens taken on recent cruises of R.R.S. ‘Discovery II’, and a total of nearly 300 medusae have been examined. The collections were made with the 2 m stramin ring trawl and the Isaacs-Kidd pelagic trawl mostly from the Bay of Biscay.

Analyses of sea water collected during 1957 at the International Hydrographic Station E1 (lat. 50° 02′ N., long 4° 22′ W.) are given here in the same form as in earlier reports (Armstrong, 1954, 1955, I957> 1958). The methods of collection and of analysis for phosphorus and silicon are substantially unchanged. Some analyses were made for ammonia by a vacuum distillation method (Riley, 1953), and for inorganic nitrogen (nitrate + nitrite + ammonia) by reduction of nitrate and nitrite with nickel (Riley & Sinhaseni, 1957) to ammonia, which was vacuum distilled. Salinities were determined by the Government Chemist's Department.

We wish to express our thanks to Lt.-Cdr. C. A. Hoodless and the crew of R.V. ‘Sarsia’ and to Capt. W. J. Creese and the crew of R.V. ‘Sula’, for assistance at sea.

Several workers have observed, in Europe and elsewhere, that Gracilaria verrucosa is a more conspicuous component of the flora in the summer months (Cotton, 1912, p. 134; Rosenvinge, 1931, pp. 602–6; Gibb, 1939, p. 378; Causey, Prytherch, McCaskill, Humm & Wolf, 1946; May, 1948), with the natural inference that its growth rate is greater in that season. However, the quantity present on the shore at any time depends also on the rate of defoliation by the waves. This will be higher in winter. Observation under more controlled conditions was therefore considered desirable.

In September 1958, Prof. J. E. Harris, F.R.S., treated freshly collected Eddystone shell gravel with a magnesium sulphate solution and so produced a rich sample of the microfauna. This has never been adequately investigated, though the macrofauna is well known. The animals collected were mostly small Malacostraca, in which Amphipoda predominated, and Prof. Harris kindly passed on to me the whole sample to examine. I have found in it thirty-four species of amphipods, isopods, tanaids and cumaceans of which no fewer than fifteen are additions to the Plymouth fauna list (see Marine Biological Association, 1957). Some indeed are new to British waters, three or four being evidently undescribed species. One of the most striking of these is described here. The collection as a whole will be reported on later.

The wide variety of reproductive patterns and behaviour in the many species of Nereidae already studied clearly justifies further research. But the life history of Nereis fucata (Savigny) is not only of interest from the comparative point of view. Its commensal habit (it occurs within shells occupied by hermit crabs) immediately gives it a special importance. This alone warrants a detailed study, particularly as no commensal polychaete has yet been reared through to metamorphosis and settlement on its host (Davenport, 1955; Davenport & Hickok, 1957). The numerous interesting problems which arise, and the experimental methods needed to study them, are, however, beyond the range of a paper on nereid development. It is therefore proposed to confine the present account to the reproduction and development up to the time when the larvae settle on the bottom. The complete life cycle, the mechanism of host-adoption, and related topics, will be reported in later papers.

The limited observations available on blood sugar levels of Mollusca suggest that they are very low. Values of 2–14 mg % glucose have been reported for Aplysia (see Kisch, 1929; Berthoumeyroux, 1935), and even the higher levels recorded for Octopus and Sepia species by Bierry & Giaja (1909), Berthoumeyroux (1935) and Derrien (1938) range only from 20 to 32 mg % glucose. The majority of these blood sugar analyses were based on the Hagedorn & Jensen (1923) technique. Landgrebe & Munday (1954) have shown that this technique may have an inherent blank error of 5 mg % glucose equivalent, and consequently it is not a suitable method for critical analyses of these low molluscan blood sugar levels.

The retinae of all the species of deep-sea fish which have been studied have been shown to contain golden coloured pigments, chrysopsins, which are especially suited to the light found in their natural environment (Denton & Warren, 1957; Munz, 1958). Amongst fish caught in shallow coastal waters this characteristic colour of retinal pigment is found only in the conger eel Conger conger (by Denton & Walker, 1958), and amongst freshwater fish only in the silver eel Anguilla anguilla (by Carlisle & Denton, 1957, referred to by Denton & Warren, 1957). Both these fish are species of Apodes, a group of which the vast majority of species are deep-water forms. Both species, more- over, begin their life in the deep sea and return to it again when mature to spawn and may therefore, in one sense, be regarded as deep-sea fish. Since immature conger eels in shallow coastal waters already have a retinal pigment characteristic of a deep-sea fish, it seems very unlikely that on returning to deep water they would change away from the deep-sea form which they already possess. It is probable therefore that the conger retains a deep-sea form of retinal pigment throughout the whole of its life.

The lophophore of Platidia, as illustrated in most memoirs and text-books, bears little resemblance to its appearance in life, no doubt because such illustrations and the accompanying descriptions were based on dried specimens. The lophophore of Platidia has been considered to be of a peculiar sigmoid type, differing from that of any other known lophophore. The dredging by R.V. ‘Sarsia’ of three species of the genus in recent years has afforded the opportunity of figuring the lophophore in its natural state, and the working out of its growth stages in P. davidsoni and P. anomioides: these were previously unknown for any species of Platidia. The third species, a new one, is described separately (Atkins, 1959).

A new species of Platidia (Brachiopoda, Platidiidae) was dredged by R.V. ‘Sarsia’ in November 1956 in the La Chapelle Bank region, attached to the dead part of the coral Anisopsammia rostrata (Pourtales). Eight entire specimens and two smashed were dredged at position 47° 30′ N., 7° 20′ W. at a depth of 870 to 970 fathoms, and one at position 47° 38′ N., 7° 28′ W. at 710 to 750 fathoms. All, except the two smallest, were a reddish brown, the coloration being due to a deposit of manganese oxide: the natural colour is a yellowish white. The dead coral was almost black with the same deposit (see Southward, 1958, p. 644).

The sense organ of Carcinus mamas located in the joint between the dactylo- and propodite possesses several types of sense cells (Wiersma & Boettiger, 1958). The most interesting types react to unidirectional displacement of the dactylopodite with equal sensitivity over the total possible arc of movement. Velocity has little influence on the discharges of the movement fibres since the maximum rate of firing is reached at a speed which is relatively little faster than the threshold. Fibres with marked differences in threshold are present for both extension and flexion. Other units in the organ react like conventional stretch receptors and give continuous discharges as long as the joint is near one of the extreme positions. Again different units are present for extension and for flexion. These position fibres are on the whole smaller than the movement fibres and their cell bodies have a more peripheral location in the organ.

At an early stage of an autecological study of Gracilaria verrucosa (Hudson) Papenfuss it seemed possible that the best growth of the plants occurred in places, such as the Achill Sound and the Church Island Channel in the Menai Straits, where, in the absence of heavy wave action, strong currents flowed over the plants. Experiments were carried out, in the sea, to investigate the effect of currents on the growth rate; the apparatus used and described here would probably be suitable for the investigation of current effects on other sedentary marine organisms.

These experiments also led to some observations on the effects of illumination on the pigmentation and growth rate of the plants which were supplemented by laboratory experiments. High intensity illumination in the laboratory also demonstrated positive phototropism in the plant.

The new species to be described here is very common in the English Channel, though like other members of this genus it is so fragile that it needs to be cultured to be effectively detected. This particular species has been under observation for some years, but publication has been deferred until sections of it could be made available. The observations involved in the taxonomic description have been based on two early isolates numbered 4 and 43 in the Plymouth collection. More recently, however, it has been encountered frequently in routine sea-water samples brought into temporary culture to record the nanoplankton forms present, and we are therefore able for the first time to give tables of seasonal and depth distributions for the incidence of the species, at various stations. In Table i of Appendix (p. 187) its occurrences are listed, all being from water-bottle samples, except those taken on 23 August 1950 and 6 November 1957 (fine tow-net) and on 19 June 1957 (very fine tow-net). Table 2 (p. 188) gives densities at different depths sampled on one day at Hydrographic Station E 1.

The deep sea prawn, Pandalus borealis Krayer, is fished extensively in Norwegian, Swedish and Greenland waters, some 4000 metric tons being caught annually, having a value of about £800,000. Its biology has been investigated by various workers in these countries. Comprehensive accounts have been given by Wollebaek (1903), Hjort & Ruud (1938), Rasmussen (1953)and Horsted & Smidt (1956). Despite this, relatively few populations have been sampled at regular intervals throughout a year. In high latitudes where much work has been carried out, ice, for varying lengths of time, prevents stocks from being sampled. Rasmussen (1942, 1949, 1953) has shown that the life history of P. borealis varies with locality in a range from southern Norway to Spitsbergen. When P. borealis was found in numbers in deep water off the Northumberland coast advantage was taken to investigate the biology of the species at the southern limit of its eastern Atlantic distribution and to compare the results with those of other workers. Knowledge of the biology of the prawn now covers the whole of its north-south distribution and some account of this is given. In addition, the study gives information on a population that has not been fished commercially and provides a more complete picture of sex reversal than has been obtained hitherto.