In a series of experiments to investigate feeding and excretion in bivalves, Mya arenaria, Venus striatula, Ostrea edulis and Cuspidaria cuspidata were fed with suspensions of Phaeodactylum labelled with 32P. Although there is considerable variation in the filtering rates, specimens of O. edulis were found to have an average rate of 6·6 ml./h/mg dry body tissue. This figure is more than six times greater than that recorded for M. arenaria and V. striatula. No filtration was recorded in the carnivore C. cuspidata.

Laboratory experiments on feeding and respiration were carried out with the copepod Temora longicornis in the Clyde sea-area. In feeding experiments, a method using radiophosphorus as a tracer was employed. The filtering rate was very variable and is probably related to size. There seemed to be a seasonal variation in filtering rates. During the summer of 1961 weekly water samples were taken for estimation of the particulate carbohydrate in the sea. There was always enough food present for Temora. Respiration was measured by using a modified Winkler method. Oxygen consumption was related to surface area, and corrections in respiratory rates were made for the size differences in the animals used. Respiratory rates were very high at the beginning of an experiment, but after a sharp fall the rate became steady in about 30 h. An indication of seasonal variation in oxygen uptake was found.

Spirorbis rupestris sp.nov. has a sinistrally coiled, unridged tube and is distinguished from S. borealis Daudin only by colour, small morphological details and striking differences in larval behaviour. Though the larvae are capable of swimming, they do not usually do so, but crawl about and soon attach themselves to rock surfaces near the tubes of their parents, particularly when stimulated by the presence of the coralline alga Lithophyllum incrustans. They will not settle on Fucus serratus.

S. rupestris is found typically on rock surfaces in well-illuminated places throughout the lower half of the shore, generally associated with Lithophyllum. It is abundant on the shores of south-west Britain, except where there is scouring by wave-borne particles.

Six species of geophilomorph centipede are reported from the littoral zone in the Plymouth area, and in two cases, where they differ from previous descriptions, the significance of these differences is discussed. It is suggested that the various British and French populations of Geophilus algarum and Geophilus fucorum may be subspecies of one polytypic species.

It is shown that Strigamia maritima and Hydroschendyla submarina differ in the way in which they have adapted to life on the shore. The former lays permeable eggs and migrates out of the littoral zone to lay them and to moult, the latter lays impermeable eggs and moults in the intertidal zone. Information on the prey of S. maritima at Plymouth is given.

The variations between some populations of littoral centipedes is discussed and possible reasons for the high density of populations of S. maritima and H. submarina are given.

In freshly collected Naesa bidentata there exists a clear dependence of respiration rate, measured in sea water, on the tidal cycle, with the maximum occurring at high tide, the minimum at low tide. In specimens that had spent 1–2 days in the laboratory the tidal rhythmicity is less pronounced due to a lowering of the Qo2-values at high tide and at the beginning of experiments. This is interpreted as reflecting differences in nutrition between freshly collected and laboratory specimens.

The results of a comparative study of the breeding biology of the Manx pectinids with special reference to Chlamys varia, C. distorta, C. tigerina, C. striata and C. furtiva are presented.

It is shown that C. varia and C. distorta are protandric hermaphrodites with separate sexual phases similar to those of oysters, and evidence is presented on the possibility of sex reversal. The other species, C. tigerina, C. striata and C. furtiva, are truly dioecious, possessing at no stage germ cells of both sexes in the same gonad and as most individuals produce only one brood, the possibility of sex reversal is excluded.

C. distorta has two large-scale or peak spawning periods, once in summer and for the second time in autumn, although some spawning occurs as a rule in most months of the year. The breeding behaviour of this species is intermittent and therefore the breeding period is prolonged.

C. varia has two mass spawnings in a year, once in June and for the second time during September and October and the breeding period is not markedly different from that observed in French waters. Spawning is usually completed within a short period. C. tigerina and C. striata spawn only once annually in June and August respectively and most individuals have only one breeding cycle during their life time. C. furtiva however, may have two spawnings in a year, but the material available was inadequate to confirm this.