In the English Channel and Celtic Sea mackerel spend the winter months on the sea floor densely packed in places where its level is interrupted by banks and gulleys.

In the early spring the fish rise to the surface and migrate to a common spawning ground that lies far out to the westward of the Scilly Islands in the vicinity of the 100-fathom contour.

The very localized positions in which mackerel spend the winter are widely distributed throughout the area in both deep and shallow water. Large schools of migrating fish converge upon the spawning ground from many directions, therefore, in the spring for spawning.

Fish that have wintered near the land must migrate offshore to reach the spawning ground; those that spend the winter on the bottom to seaward of the spawning ground must migrate shorewards to reach it. Off the south-west of England there is no single shoreward migration to spawn in shallow water as has previously been thought.

In the North Sea the chief spawning grounds of the mackerel are also near the 100-fathom contour which, in that region, happens to lie very close to the land in the Skagerrak and along the Norwegian coast. The chief spawning migration of the North Sea mackerel is therefore towards the coast from offshore localities.

This migration is, at the same time, chiefly from shallow to deeper water.

Existing information concerning the mackerel populations on the westernside of the North Atlantic points to the probability that their spawning habits and migratory movements do not differ greatly from those of the mackerel in North European waters.

Fertilizations of Ophelia bicornis Savigny were made and the larvae reared. This is the first time the larval development of any member of the family Opheliidae has been described.

The trochosphere is small and somewhat yolky; it has a broad prototroch, a narrow telotroch, a strong apical tuft and a long anal cilium.

Annulation is accompanied by the appearance of parapodial lobes and bristles. When the first pair of bristles of the third setiger protrude the larva is ready to metamorphose. It has two, sometimes three eyes.

The larva in its later stages can adhere strongly to solid objects, such as sand grains, by a secretion from the four anal papillae and the parapodial lobes. This is interpreted as an adaptive aid to settlement on sand banks swept by strong currents.

At metamorphosis the larval external cilia are lost and the bristles rapidly elongate, especially those of the third setiger.

Some of the larval bristles are slightly winged. So far only capillary bristles have been known in the Opheliidae.

It is pointed out that a development such as that of Ophelia is more typical of polychaetes as a whole than are the developments of certain species commonly used as text-book types.

The breeding season of the lugworms of the Whitstable area is a sharply defined one, extending for 14 days between the new moon and full moon spring tides in the second half of October. Spawning begins slowly and reaches a maximum at the intervening neap tides and then declines in intensity.

Both eggs and sperms are discharged from the burrows at extreme low water to lie on the surface of the sand. Here fertilization occurs.

No germ cells were detected in the body cavity from November to June, but from August onwards to the end of October 98% of the adult worms are ripe.

At the end of the spawning period about 40% of the adults die.

A brief description of gametogenesis and of the mature gametes is given.

Germ cells are discharged through the nephridia.

It is suggested that the genera Apomatus and Protula should be revised to reflect the close similarity between P. tubularia and the two species of Apomatus, and the dissimilarity of Protula intestinum. It is further suggested that the presence or absence of an operculum is not a sufficiently important character for distinguishing Apomatus from Protula, or Filograna from Salmanica; and therefore that these two pairs of genera should be fused into two genera.

Spisula subtruncata is a shallow-burrowing member of the Mactridae which inhabits silty sand. Adaptations to such conditions include long frontal cilia on the gills (Atkins), and the presence of a siphonal membrane with associated mantle folds over-arching a waste canal, as postulated by Kellogg for allied species.

The mantle edges are free ventrally, but are normally closely applied except for a short distance at the base of the inhalant siphon, an effective fourth pallial aperture being so formed. Through this opening material from the waste canal is ejected.

Lutraria lutraria is a deep-burrowing species belonging to the same family. The general resemblance to Mya arenaria is due to convergence. Cleansing currents resemble those of Spisula subtruncata and there is a similar waste canal, but the siphonal membrane and the long frontal cilia associated with a silty environment are absent.

The external features of Skeneopsis planorbis (Fabricius) are described and compared with those of Omalogyra atomus (Philippi), Rissoella diaphana (Alder) and R. opalina (Jeffreys).

The foot has a large posterior mucous gland (Figs. 1 and 4, Pm; PI. IV, figs. 1 and 2, Al, Pl), its secretion forming a thread on which the mollusc can climb from one level to another.

Correlated with their small size are modifications of the pallial organs. Skeneopsis, the largest and least specialized, has a bipectinate osphradium, but the gill is reduced to nine filaments; the anus lies well within the mantle cavity. In the other genera osphradium and ctenidium are lost, though the latter may be represented in Rissoella by a small tract of ciliated epithelium. In the absence of a ctenidium the animals depend entirely upon pallial respiration and the stream of water through the mantle cavity is maintained by other means: from the anus strips of ciliated epithelium pass forward to the mouth of the mantle cavity, causing a strong exhalant stream and carrying away the faecal pellets. There is a compensating inhalant flow. The kidney (PI. IV, figs. 1 and 2, K), with its rich vascular supply, has migrated into the tissues of the mantle, increasing its respiratory efficiency.

Stolonica socialis (Hartmeyer) and Distomus variolosus Gaertner are two species of styelid ascidians with a capacity for budding and colony formation, found on both sides of the western end of the English Channel. Distomusoccurs immediately below the level of extreme low spring tides, commonly encrusting the sides of rocks and laminarian bases. Stolonica is more usually found by dredging in deeper water, on the upper sides of stones or gravel bottom. Their external appearance and general internal anatomy have been well described and beautifully illustrated in the monograph of Lacaze-Duthiers and Delage (1892), while the process of budding has been investigated by Selys-Longchamps (1917).

The production, longevity, growth, regeneration and reproduction of Laminaria saccharina (L.) Lamour. on the Devon and Argyll coasts are described.

Bathymetric zone and habitat control the fertility and longevity of the gametophyte and consequently the production of the sporophyte. Sporophytes develop at the higher levels during the winter, early spring, late summer and autumn, and at the lower levels during spring, summer and autumn.

Longevity of the sporophyte depends on season of germination, bathymetric zone and habitat. Winter sporophytes rarely persist to maturity. Spring sporophytes form the bulk of all L. saccharina populations except on very sheltered coasts in the sublittoral zone where summer sporophytes may be equally numerous. On the British coast the life-span of a L. saccharina sporophyte does not exceed 3 years.

Dr T. B. Reynoldson of the Department of Zoology, University College of North Wales, Bangor, found some large enchytraeids on the shores of the Menai Straits. He suspected that it was an undescribed, or at least a rare and interesting species, and kindly sent six specimens to me for further study. I find that the specimens are indeed to be ascribed to a new species, which is here named Lumbricillus reynoldsoni, in recognition of the finder's prominent work on the ecology of Lumbricillus lineatus Mull, and Enchytraeus albidus Henle.

The 1947 records of the seasonal abundance of the pelagic young stages of teleosteans in the plankton of Plymouth off-shore waters are a continuation of the series of observations made by Mr F. S. Russell (1930–47). The form of the previous reports is retained. The dates on which collections were made are given in Table I, and the monthly average catches of young fish in Table II. The fortnightly averages of all young fish less clupeids are shown in Fig. I, together with the corresponding curve for the period 1930–34.

Experiments with larvae of Ophelia bicornis Savigny have shown that they metamorphose most readily in sand from their natural habitat and with hesitancy or not at all in sands from other sources. Their natural sand consists largely of smooth rounded grains of quartz, very uniform in size; sands of smaller and more angular grains are unfavourable to settlement and metamorphosis. It appears that size and shape of the sand grains, or perhaps, more likely, the sizes and shapes of the interstices among the grains, perceived probably by the tactile sense, is the main stimulus to metamorphosis. Chemical substances dissolving out of the sands do not seem to be responsible for this.

There is a period of time, amounting under favourable conditions to several weeks, during which an Ophelia larva is able to settle and metamorphose as soon as it comes into contact with a substratum suitable for adult life.

The ability of the larvae to distinguish bottom deposits suitable for adult life from those which are unsuitable must be of great advantage to the species in maintaining normal distribution and in conserving larvae.

In The Times of 31 March 1884, it was announced that a meeting would be held that day in the rooms of the Royal Society for founding a society having for its purpose ‘the establishment and maintenance of a well-equipped laboratory at a suitable point on the English coast, similar to, if not quite so extensive as, Dr Dohrn's Zoological Station at Naples’ (M.B.A., 1887a). With Prof. T. H. Huxley in the chair a gathering of distinguished gentlemen gave reasons why such a laboratory should be built. All stressed what its value would be from the purely scientific viewpoint, and all were agreed that both by fundamental research and by more direct investigations on our food fishes, knowledge of economic import would be gained. The last speaker, Mr George J. Romanes, said that there was one function of the proposed laboratory which had not received the attention it appeared to deserve; he meant the investigation of invertebrate physiology. ‘In the invertebrate forms of life’, he said, ‘we saw life in its simplest shape, and in the shape which best admitted of observation and experiment, with the view of throwing light upon most of the great questions relating to the processes of life’ (M.B.A., 1887b).