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.

Since the surveys described in our last report (Crisp, 1958) on the distribution in north-west Europe of the immigrant Australasian barnacle, Elminius modestus Darwin, the species has become much commoner along the western coasts and has finally spread to Ireland (Beard, 1957). In this report we present the results of surveys made in 1958–9 along the eastern side of the Irish Channel and in the Isle of Man, as well as full records of a survey of the Irish coast in 1958. The methods employed were similar to those described previously (Crisp, 1958; Bishop & Crisp, 1958).

The Scaphopoda or tusk-shells are the smallest and most uniform class of molluscs. They burrow in sand of medium to coarse shelly grade, and specialize on a diet of hard-shelled microbenthos, particularly Foraminifera. Dentalium entalis L. is the commonest West European species, and may become locally dominant. Le Danois (1948) has described a ‘Dentalietum’ in deeper water sandy ground at about 100 fathoms in the southern Celtic Sea. Stephen (1933) discusses the distribution of D. entalis in the northern North Sea, where it is largely restricted to the ‘Offshore zone’, the southern limit being marked by the 60 m line. Low salinity is probably responsible for its absence from the southern North Sea; and in general it seems limited more by hydrographic conditions than by the relative abundance of foraminiferan food. For example, in Stephen's Thyasira+ Foraminifera Zone, it is no more than sparsely present. Holme (1953) finds Dentalium entalis rare or absent near Plymouth, though it was relatively common at the Eddystone Grounds at the end of last century (Allen, 1899). It has today receded to the mouth of the Channel, in coarse deposits resulting from fairly strong scour, and Holme suspects it to be one of the list of species sensitive to recent hydrographic changes in the area.

For the living material used in this study I am greatly indebted to Mr N. A. Holme, who collected it in deeper water in the Celtic Sea on a 1953 cruise of the R.R.S. ‘Discovery II’. With it were collected Chlamys opercularis, Caryophyllia and in places Astropecten irregularis; there were also many of the tusk-shaped serpulid tube worm Ditrupa arietina which as I found can impose a neat deception on the uncritical hunter for scaphopods.

No account exists of the mechanism of food collection of nudibranch larvae, and, in fact, it has been considered unlikely that feeding does take place in these forms. Thorson (1946, p. 275) states ‘Nudibranch larvae will normally take no—or only little—food from the plankton’.

In May 1958 it was thought that all species of Pogonophora so far discovered in the north-east Atlantic belonged to the genus Siboglinum Caullery (Southward & Southward, 1958). Since then I have had the opportunity of examining further collections from deep water off the British Isles and Spain. At least two species of multitentaculate pogonophores have been discovered, and re-examination of some material collected in May 1958 shows that one of the species was also present in these collections. Although considerable material belonging to other species remains to be worked up it has been thought worth while to describe these two species first. One is widespread and can be locally abundant, while the other is the largest pogonophote so far found in the Atlantic. Both are the first Atlantic representatives of their respective genera.

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.

Apart from the extensive egg surveys carried out by Norwegian workers (Runnstrom, 1941) most of the investigations on the spawning of the Atlantic Herring have depended on studies of the distribution of the spawning fish, on captures of newly hatched larvae, and on records of the occurrence of herring eggs in the stomachs of predatory fish species (principally haddock). With the exception of recent observations by Bolster and Bridger (1957), attempts to sample egg concentrations quantitatively in the North Sea and neighbouring areas have usually proved abortive. In consequence little is known of the distribution and density of eggs on the spawning grounds, their percentage fertilization, mortality during the egg stage, hatching rate, and the relationship between the distribution of eggs and the nature of the sea-bed.

Among the parasites of the branchial chamber of the flatfishes of the Eastern North Atlantic, those belonging to the genus Acanthochondria (fam. Chondracanthidae, tribe Cyclopiformes) occupy a conspicuous place. Both their relatively large size and their abundance, render them easily noticeable even to a casual observer, in spite of the protective nature of their environment. It is a reflexion on the state of our knowledge of marine parasites that, not withstanding their accessibility, very little is known about the animals of this genus.

The genus Acanthochondria was erected by Oakley (Leigh-Sharpe and Oakley, 1927) for the chondracanthids, which until then were included in Chondracanthus Delaroche, 1811, and which differed from the other members of that genus in the absence of the cephalic barbs and the dorsal and ventral processes. They were also characteristic in their preference for the flatfish hosts.

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.

Since MacMunn (1885), the nature and distribution of naphthaquinone pigments in sea urchins have been widely surveyed, and the main findings have been summarized in reviews by Lederer (1952), Fox (1953) and Thomson (1957). Among spinochromes and echinochromes, the most unusual one is the Spinochrome E discovered by Lederer (1952), which is insoluble in ether.

Recently, the author has examined the napthaquinone pigment in the echinoid, Psammechinus miliaris (Gmel.), and has found a similar pigment to Spinochrome E together with other common spinochromes.

In spite of the keen interest evinced in the taxonomy of the parasitic copepods, there is little information on their metabolic rate, though the respiration of free-living forms has been studied by such workers as Marshall & Orr (1955, 1957), Clarke & Bonnett (1939), Zeuthen (1947), Raymont & Gauld (1951), Gauld & Raymont (1953) and Conover (1956). Since the rate of oxygen consumption is a reflexion of the metabolic rate of an animal, it was felt that a study of the rate of oxygen consumption of a copepod parasite would be of interest. Chondracanthus zei De la Roche, 1811, is easily available and large.

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.

Plymouth scad (horse-mackerel) Trachurus trachurus (L.) are known to harbour three species of monogenean trematode gill parasites, of which two belong to the Gastrocotylidae and one to the Microcotylidae. The oncomiracidia (= newly hatched larvae) of these parasites have already been described (Llewellyn, 1957a), but nothing is known of the developmental stages intervening between the oncomiracidia and the adults. Bychowsky (1957) has stated that some information is available about the larval development of 13 monogenean families, leaving 15 families, including the Gastrocotylidae, about whose larval development nothing is known. The ontogenetic development of the Gastrocotylidae is of especial interest since the oncomiracidia are bilaterally symmetrical, but the adults invariably show an extreme degree of asymmetry.

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.

Biebl (1939a, b) has found that algae from various ecological groups show marked differences in their resistance to changes in the temperature of the surrounding sea water. He regards this temperature effect as an important factor influencing the distribution of different intertidal algae and points out that a change of only 2° C may prove critical with certain species. One of us (A.D.B.) has studied the resistance of sporelings of various common inter-tidal red algae to changes in environmental temperature and has obtained results similar to those of Biebl.

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.

The species with which this paper deals was originally included by Linne in the genus Solen and was there retained to be included under that name in the magnificently illustrated account of this genus by Deshayes (1845–48). It was later placed in a new genus Ceratisolen by Forbes & Hanley (1853) who considered that it formed ‘the connecting link between the Solenidae and Solecurtidae’. This procedure was followed by Jeffreys (1865). More recently the Solecurtidae were shown by Graham (1934b) having ‘regard to such features as shape, presence of a cruciform muscle and the structure of the foot, siphons, adductor and pedal muscles, supra-axial extension of the outer demibranch, palps, and style-sac and intestine’, to belong to the Tellinacea, a view fully supported by this author (Yonge, 1949). Assigned later to the genus Pharus which has priority over Ceratisolen, this ‘connecting link’ of Forbes & Hanley continued to be associated with the Solenacea by Thiele (1935) in his great systematic account of the Mollusca.

A sea anemone, normally a passive-looking animal, reacts to suitable food-stuffs by a series of fairly complicated activities. When its tentacles encounter solid food there is, first of all, a discharge of cnidae, which poison living prey and adhere to the food mass. These cnidae are independent effectors, responding directly to external excitation (Pantin, 1942). Next, the tentacles clasp the food and bend towards the mouth; they push the food into the mouth, and the pharynx draws it down into the coelenteric cavity where it is digested (Pantin & Pantin, 1943).

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 order to evaluate the biological significance of luminescence, it is desirable to know how weak light affects the behaviour of marine animals, and what intensities they can see. Much information is available concerning the attractive power of bright lights, and light directed movements (see Verheijen, 1958, for example), but little for weak point sources. Weak coloured lights have been used by Baylor & Smith (1953) to trap freshwater arthropods.