Anew species of deep-water txachymedusa from the North Atlantic is described and named Colobonema apicatum. Most specimens occurred deeper than 1500 m.

Measurements have been made of the quantity and type of food assimilated by adult female Calanus helgolandicus (Claus) during the summer months.

Animals kept in the dark at 10° C under a continuous flow of ‘outside’ Plymouth sea water (0·95–2·50 mg insoluble organic material/1.) removed 26·0–66·5 μg/day/Calanus, of which 74–91% was actually digested.

Volumes of sea water filtered daily varied between 10·0 and 36·0 ml./ animal, with an average of 21·5.

The animals preferentially selected a diet of high organic content from the particulate food available, digesting average daily quantities of 18·1 μg carbohydrate, 6·5 μg lipid and 2·7 μg protein.

The average amount of food digested daily accounted for 25·3% of the dry weight and was equivalent to an average respiration rate of 26·5 μl. O2/ animal/day, which adequately accounts for the highest values reported by others for C. finmarchicus (Gunnerus) kept under similar conditions of light and temperature.

These results, which provide direct evidence that Calanus obtains the bulk of its food from particulate material present in the sea, have been discussed with especial reference to Pütter's hypothesis.

Previous plankton work at Plymouth is reviewed briefly, and the limitations of the stramin ring trawl as a quantitative sampler discussed. The distribution of certain zooplankton ‘indicator’ species caught in hauls of the 2 and 1 m ring trawl during cruises in 1955 and 1957 is described in comparison with regular 2 m hauls taken throughout the same years at two stations near Plymouth.

The results support previous suggestions that ‘western’ water at Plymouth is derived from a region to the south of Ireland, i.e. from the north-west, and is not now in the direct path of the flow of water into the English Channel from the west.

An apparent northward spread of the warm-water copepod Euchaeta hebes during the past 50 years may be connected with the rise in sea temperature over the same period. It is suggested that related changes in distribution might be responsible in part for changes in the macroplankton community off Plymouth since the 1920's.

The salinity tolerance of herring 9-ca 24 cm in length was found to lie between 6‰0 and 40–45‰0.

Determinations of changes in weight and blood concentration (by measurement of the freezing-point), when herring were transferred from one salinity to another, demonstrated that extensive changes occurred in the blood. Under these conditions the herring experienced and survived blood concentrations equivalent to salinites of 13–22·5‰. A recovery to near normal (δ0·95 ≡ 15·8‰) took place in all the salinities within the tolerance range.

Badly descaled herring in sea water showed large increases in blood concentration before death.

A study of the kidney of the herring indicated that the ability to withstand the low salinities for long periods probably rested in the high glomerular count of the kidney.

The importance of damage to the skin for survival is discussed in relation to tagging experiments.

The results are also discussed in relation to the evolution of the herring.

The biometry of the Clyde population of long rough dabs has been studied and compared with the descriptions of the European race given by Norman in his monograph of the flat-fishes. The data consist of various body measurements together with the results of scale counts, fin ray counts and vertebral counts. The fin ray numbers fit into a pattern of increasing number with high latitudes when compared with other published data. There is a correlation between the number of anal and dorsal fin rays, and between these and the number of vertebrae. The variations that were found in the vertebrae of fifty-one fish are described. Only one sinistral long rough dab has been found out of 2357 specimens examined. From the British fishing statistics it is shown that the long rough dab is of little, and declining, commercial importance. In Canada, however, the American subspecies is becoming more important commercially.

Six naupliar and a cyprid stage for B. balanus are described and diagrams given for the general outlines and individual appendages. Sizes and setation formulae are given.

The naupliar stages resemble both B. balanoides and B. crenatus; attention is drawn to some distinguishing features and a key for the separation of the species is provided.

Yield of the supra-littoral chrysomonad Monochrysis lutheri varied directly as vitamin B12 concentration between the limits 0·1 and 100 μμg/ml., each μμg of vitamin supporting 0·55 × 106 cells. Between the same limits of concentration there was to be seen no significant deviation in initial rate of cell division from the mean value of 1·1 divisions per day (phototrophic growth: 2000 lux, 20° and 15° C), the conclusion being that limitation of the division rate does not occur before the concentration vitamin B12 has dropped below 0·1 μμg/ml.

With the exception of a few specially designed models, most under-water cameras today employ no means of pressurizing, or at best merely have a Schrader valve fitted to the case which can then be pressurized, prior to each dive, with a few strokes of a bicycle pump. This method has one severe drawback in that the majority of camera cases are better able to withstand external rather than internal pressure. The chances of a case exploding or blowing a gasket while pressurized prior to a dive are far greater than those of implosion of a non-pressurized case in a comparable depth of water.

The tellinid Macoma balthica moves extensively about the surface of the sand, its activities not being restricted to vertical movements as hitherto supposed.

These horizontal migrations comprise a movement towards the sun followed by a movement away from it. If there is heavy cloud movements still occur, in summer at least, but are at random.

Other intertidal species indulge in similar movements, possibly indicating a widespread habit which confers the advantage of bringing the animal into contact with surrounding areas while maintaining its station on the shore.

The variation in convexity of the valves and the development of the pedicle opening in M. echinata is described in shells from a length of 1·2 mm to 13·5 mm and it is concluded that the differences in shell shape and form of the pedicle opening between M. truncata and echinata are of no more than specific value and that the latter species should be transferred from Pantellaria back to Megerlia.

Megerlia truncata and M. echinata dredged by R.V. ‘Sarsia’ have been examined living. The growth stages of the lophophore are described and figured, the series being fuller in M. echinata than in M. truncata. The adult lophophore of M. truncata has been sectioned and its structure described.

The ciliary feeding mechanism in Megerlia is similar to that already described by the author in brachiopods with plectolophous lophophores

An account is given of the mortality of Ostrea edulis at the Tal-y-foel oysterage from 14 days to 11½ years after metamorphosis. In the first year after settlement most of the deaths occur in the late summer, autumn and spring, and few during November-February. A survival curve has been drawn up and shown to correspond with Pearl's ‘positive skew rectangular type’. On the average, from 1000 14-day-old spat, 78 survive for 6 months, 18 for 18 months and 7 for 11 ½ years. At this oysterage the major predators are rare or absent, and the cause of most of the mortality is unknown.

Lichina pygmaea failed to recolonize areas cleared from within the lichen ‘mats’ after four years. A retrogression of the lichen was observed in some instances over periods of 5–7 years. A complex of factors governs the size reached by a lichen tuft; more rapid growth occurs in regions where there is some moisture retention during tidal periods. Although changes occurred with individual ‘patches’ of lichen, the total Lichina cover on a rocky surface remained much the same over a 7-year period.

Macerated tissues of whole Arenicola marina, when injected into the body cavity of male worms, induce spawning after a prolonged latent period of, generally, 60—90 min. The nature of the spawning reaction is described. Emulsified tissues were submitted to heat, ultra-filtration, extraction by fat solvents and saponification. The technique is described whereby the products of these treatments were assayed for potency in inducing the spawning of male worms. The active substance proved to be a lipid and upon rigorous saponification the fatty-acid fraction was found to induce shedding, but the unsaponifiable fractions failed to do so. The active substance was also found to be a normal tissue constituent of male, female and immature worms, but it is concentrated in the gut and coelomic contents. Tissue extracts appear to induce spawning primarily by the breakdown of the sperm morulae in the coelom to free spermatozoa, but there may also be some modification of the action of the nephromixia. It is suggested that the active substance found in the tissues provides the ‘internal stimulus’ by which spawning is normally induced. Evidence for this suggestion is that it is derived from the tissues of the worm and that it appears to be a specific chemical fraction of the tissues which is effective. In addition, tissue extracts induce a normal spawning reaction and there appears to be a relationship between the temperatures at which the active substance is most potent in inducing shedding in the laboratory and those prevailing on the shore during the breeding season. The possible mode of release of the active substance is discussed.

C. ericina Parke & Manton has been re-investigated to add salient features of micro-anatomy from the electron microscopy of thin sections and also to add photographs of living cells taken with anoptral contrast light microscopy.

The most important new observations concern the scales which are shown to be essentially two-layered plates in which the layers in the very large spined scales have become separated except at their edges, with the outer layer greatly hypertrophied to produce a hollow spine with a flared base closed at the bottom by a flat plate. The patterns of external marking on the two layers are very similar in both plate-scales and spines in this species and the orientation of both with respect to the cell surface has been demonstrated by a section of the scales in situ.

A brief account is given of the sessile animals and algae found by diving on the Lulworth Banks. The numbers of a sponge, a sabellid worm and bryozoari were counted over a total area of 650 m2.

Evidence is presented to suggest that the salinity tolerance of the adult North Sea Asterias rubens is around 23‰, whereas that of the Baltic Sea animals is 8‰. This, together with other evidence outlined, is thought to be sufficient reason to justify the use of the term ‘physiological race’ where these two populations are concerned.

Adult A. rubens from the North Sea is incapable of any degree of weight regulation in diluted media within the ecological temperature range, size or state of the breeding cycle.

Similarly, it is incapable of any osmotic regulation and it is suggested that the two main coelomic cavities constitute an osmotic unity.

The use of tetraphenylarsonium chloride for the detection and determination of perchlorate in sea water has been investigated. An aqueous solution of this reagent gives a visible precipitate of tetraphenylarsonium perchlorate with sea water containing 5 μg ClO4-/ml. within 10 min. For the quantitative determination of traces of perchlorate, potassium perrhenate is added to the water sample, and the tetraphenylarsonium perrhenate, which is precipitated by addition of the reagent, co-precipitates tetraphenylarsonium perchlorate. Perchlorate is determined in the mixed precipitate by infra-red absorption spectrophotometry. Using 100 ml. of sea water, a sensitivity of 0·03 μg ClO4-/ml. can be attained, with a coefficient of variation of ca. 10%. No interference is caused by the ions normally present in sea water.

Styela mammiculata breeds during the summer, probably in August and September. Some eggs are self-sterile. Embryos show a yellow crescent of presumptive muscle cells. The larvae hatch by means of an enzyme. The larval sensory apparatus includes a large unicellular otolith and a small ocellus, which is composed of a single pigmented retinal cell and a single lens cell.

Seasonal changes in the gonads of both sexes of Venus striatula were followed by macroscopic and microscopic examination, in over 700 animals from a population consisting mainly of one year-group. The sex ratio was approximately equal, and no hermaphrodite adults were found.