Nitrogen retained and nitrogen excreted by Calanus finmarchicus (Gunnerus) have been measured at all stages of development from egg to adult; and the percentage of food digested by adult females grazing algal diets has been estimated by two separate methods. The data have been used to calculate gross efficiency of growth by the young stages as well as that of egg-production by the adult female. They show that during a life-span of approximately ten weeks the animal uses 24% of the nitrogen it captures as food in order to build new tissue and produce eggs; the remaining larger fraction is lost as faecal pellets, moults and excreted end-products of metabolism.

A sensitive, specific and precise method for the determination of ammonia in sea water is presented. The method depends upon the oxidation of ammonia by chloramine-T and subsequent coupling with phenol to produce indophenol blue in an n-hexanol extract. Molar absorption coefficient ca 84,000. Values of ammonia measured in samples from the English Channel are given and the effect of freezing on samples for ammonia analysis is discussed.

A new species of Breviraja is described from a pair of fish caught by line at nearly 2500 m depth in the Bay of Biscay. Distinctive characters include: the sparse distribution of denticles and spines, small number of teeth, position and size of the orbits, and very pale dorsal surface.

A tagging investigation on the ormer (Haliotis tuberculata L.) has been carried out for the Guernsey States Sea Fisheries Committee. Cementing plastic discs to the shell has proved a satisfactory technique since substantial numbers of 40—50% were recovered after 1 and 2 years in the open sea off the west coast of Guernsey. From the increase in shell size of the recovered specimens the mean growth rate has been shown to be about 15 mm of shell length per year up to a shell size of 50 mm, and thereafter decreasing until at 100 mm length growth is negligible. The growth parameters K and L∞ have been calculated. Annual rings were frequently, though not invariably, found on the shell. From the frequencies of the shell-ring lengths in the smaller ormers estimates of the shell size reached 1 and 2 years after settlement have been made. A single annual ring was also found with the majority of the larger shells (> 50 mm), though when growth did not exceed 4 mm in a year the rings were not included owing to the difficulty of separating annual rings from possible disturbance rings caused by the process of tagging. The position of the annual ring varied, being closer to the outer edge of the shell with increasing size. Measurements of the length increase from one annual ring to the next indicated rates of growth closely comparable to those obtained from tagging measurements. Damage to the shells by the boring sponge Cliona lobata Hancock is very widespread, particularly in the larger ormers living below the tide marks.

Various aspects have been studied of the relationship between the entocommensal nemertean Malacobdella grossa [O.F. Müller, 1776] and its host on the Yorkshire coast, the lamellibranch Zirfaea crispata L. Larger host populations clearly show both a higher overall percentage infection and greater numbers of multiple infections. Larger hosts tend to harbour larger Malacobdella; allied with this fact is the conclusion that the older the host population the more restricted is the availability of potential hosts for future infections.

The larva of the fly Canace nasica Haliday feeds on Enteromorpha in the intertidal zone. Its pupae, like those of a number of other intertidal flies, have plastron-bearing spiracular gills. The gills are unlike those of any other known Diptera in that they are modified spiracles: those of other flies are modifications of the body wall adjoining the spiracle, or of both the body wall and the spiracle. Although the spiracular gills are pupal structures, they are the respiratory organs of the adult before it emerges from the puparium.

Diagnoses and descriptions are given of two new species of marine planktonic flagellates of the class Chrysophyceae; Paraphysomonas imperforata and P. foraminifera. Both possess unequalflagella, the longer pantonemic, the shorter simple. Chromatophores and stigma are absent, phagotrophic nutrition occurring. Surface scales examined by electron microscopy are the best means of identification, those of the latter being perforated by many holes. Each scale of both species has a central dome, bearing a long spine, and a shallow annular fold with a radius half that of the scale.

The size-frequency distributions of monthly collections of Aplysia punctata from a sublittoral population in Trearddur Bay, Anglesey, made during the period from July 1964 to October 1965, indicate that the animals live for one year and that the major recruitment to the population occurs in the autumn. The Aplysia in this area are restricted mainly to sublittoral beds of the red alga, Plocamium coccineum, and the majority of animals feed, copulate and deposit spawn on this seaweed. The animals spawn from May, when the sea temperature reaches a minimum of about 9–9·5° C, until about October, with a maximum output of spawn in the late summer when the animals are fully grown. Aplysia in Trearddur Bay do not migrate inshore; instead, they probably colonize the intertidal region after being accidentally washed inshore from the sublittoral habitat. Intertidal and shallow-water Aplysia are larger than those from deeper water possibly because of the greater abundance of food. Similarly, it is thought that Aplysia found in the intertidal zone are brown and olive-green because they eat a particular alga or combination of algae present in this habitat.

Thin-layer chromatographic procedures using silica gel and glucose have been employed for the examination of the pigments of twenty-three species of marine phytoplankton, drawn from a number of classes. Several new xanthophylls have been found including one similar to fucoxanthin which is the principal pigment in an, as yet, undescribed member of the Haptophyceae. The pigment array of a species of Olisthodiscus sp. (Plymouth no. 239) differs considerably from that of members of the Xanthophyceae and this species is probably incorrectly classified.

The oceanic scyphomedusa Pelagia noctiluca (Forskål) was exceptionally abundant in the coastal waters of Devon and Cornwall in the year 1966. Very young stages were taken only in the months of October, December, January and early February, indicating that the medusa has a restricted breeding season.

Anthomedusae of the family Calycopsidae are in general oceanic in distribution. The only species recorded from British waters is Bythotiara murrayi Günther, reported from fairly deep water far offshore from the west and southwest coasts of Ireland. Its early stages have been unknown. A very young medusa caught at the surface in the Firth of Clyde has been reared through several stages, which are described and figured. It is considered to be a young B. murrayi.

Of the seven British species of Eurydice two are intertidal, three range successively from the immediate sublittoral to the edge of the continental shelf, and two predominate at the edge of and beyond the shelf. Most species have been recorded from the benthos and from surface plankton. E. affinis is recorded for the first time in Britain, among E. pulchra in intertidal sand in the Bristol Channel.

Schistomysis spiritus (Norman) breeds throughout the year in the Clyde and in Loch Ewe, Wester Ross, but breeding is more intense at some seasons than others. The over-wintering population in the Clyde breeds in March/April, the progeny growing and becoming sexually mature in July/August to produce a further generation which matures and breeds in October/November. In Loch Ewe the over-wintering population breeds in February, March and April and members of this spring generation begin breeding in May and continue to breed until September; the number of S. spiritus breeding in Loch Ewe decreases sharply after September and no autumnal peak of breeding, such as that in the Clyde, was found during the period investigated. The number of young carried in the marsupium varies seasonally, being 20–30 in May/June and 2–6 in midwinter. The food and the horizontal and vertical diurnal and seasonal movements of this species are discussed.

Anchor-dredge samples of the benthos in Weymouth Bay and Poole Bay were taken after the severe 1962–63 winter to ascertain what changes in the fauna had occurred. The same station positions as had been previously sampled in 1958 and 1959 were re-sampled in 1963–64 and the results from each Bay compared.

Most species had survived the previous winter, when sea temperatures had probably been at 3° or below for about a month, but populations of the bivalve molluscs Venus verrucosa and Venerupis rhomboides, previously common in the area, had suffered severe mortalities, none being taken in the 1963–64 samples. The brittle star Acrocnida brachiata had also disappeared from the samples, and many other invertebrates appeared to have declined in numbers. Two cold-water species, Spisula elliptica and Buccinum undatum, showed if anything a slight increase, perhaps reflecting colder sea temperatures over the past few years. Crepidula fornicata also showed an increase in numbers.

Mortalities were not necessarily of species close to the limits of their range, some of the latter having survived with no noticeable decline in numbers.

Nomograms are presented for solving the equations relating the concentrations of chlorophylls a, b and c to sample volume and the extinctions of acetone extracts at three wave-lengths.

In the coxal region of Palinurus vulgaris Latr. the following proprioceptors are present: (1) a thoracico-coxal muscular receptor, (2) two innervated elastic strands (depressor and levator receptors), and (3) a coxo-basipodite receptor. Thus, Palinurus has the same number of these organs as some Brachyura and Anomura, but differs from Homarus and Astacus, which have five of them.

In all the five thoracic segments carrying the legs the receptor organs in Palinurus originate on special receptor rods which are thin projections of the endophragmal skeleton.

The muscle elements of the muscular receptor are surrounded by connective tissue which in the proximal part of the muscle forms a thick sheath. To the receptor rod the muscle is attached by a short tendon. The motor fibres reach the receptor muscle at about the midpoint of its course.

Diving observations and more wide-spread coverage by Asdic show that the late Holocene basal neritic deposits of the broad bay between The Lizard and Start Point are represented by three main facies whose character depends on the two bed-transport paths converging there. The sheet sands laid at the end of the path with a good supply show a progressive geographical change in texture. On the other path, where sand is in short supply, there are elongated patches of somewhat coarser, well-sorted sand with ‘silt’ balls, alternating with shell-rich gravel patches. While the sand patches are laid out along the path of the strongest tidal currents, the ripple marks of the gravel can only be constructed by long waves from the Atlantic.

The algal symbiont of Convoluta roscoffensis (Graff) has been studied with the light and electron microscopes both in situ in worms collected from four localities on the coast of Brittany and in various forms of isolates in culture. The same organism has also been obtained from populations of free-living monads collected from sand and water samples adjacent to the Convoluta colonies. Its structure and behaviour in culture are described and illustrated. Platymonas convolutae sp.nov. is a very distinct species with a rough-surfaced theca and a pyrenoid with some new characters not previously recorded in other members of the group. Some new information on scale and theca production from the Golgi system has also been obtained.