1. Young angler-fishes have been kept alive and in health for periods varying from a few weeks to eleven months. They were sometimes hand-fed on dead fishes and sometimes allowed to catch living prey. They grew at an average rate of about eight and a half inches per annum. All had strongly marked individual characters.

2. With pelvic and pectoral fins a slight hollow is made in the sand into which the angler settles itself. Its upper surface is now flush with the ground, and the colour and colour mottlings are closely matched to the surroundings. The bordering tags of skin break up the outline.

3. Breathing movements occur at relatively long intervals. The expiratory currents are discharged in the axils between the pectoral fins and the trunk, and are deflected vertically upwards.

1. This paper deals with certain experiments on training fish (Ctenolabrus rupestris L.) to swim round obstructions to reach food, for the purpose of investigating how their learned response was developed. The whole question as to how learning which involves “problem-solving” is rightly to be interpreted and harmonized with our knowledge of conditioned responses, presents difficulties which have not yet been adequately faced.

2. A description is given of the results of experiments carried out on eleven fish. The fish had to learn a detour route either into a pot or round glass plates. Attention may be drawn to the great diversity in the behaviour of individual fish, both in their reactions to the obstruction at different stages of training, and in the method by which they succeeded in passing it. Some individuals are evidently more capable of profiting by experience than others.

1. An air turbine ultracentrifuge suitable for biological work and capable of developing a centrifugal force from 10,000 to 500,000 times gravity has been described. Advantages of the ultracentrifuge are: (1) The temperature does not vary in the centrifuge chamber over 2 or 3 degrees from that of the atmosphere; this is not sufficient to be an important factor in general biological work. (2) The cost of constructing the apparatus is very low in comparison with that of other high speed centrifuges.

2. A modification of the air turbine ultracentrifuge in which the turbine rotor drives a second rotor, in this case the centrifuge rotor which spins in a vacuum, has been described. Here the centrifuge chamber is thermally insulated which is an important item in preventing troublesome convection currents from arising in the centrifuged material where such special problems as the rate of molecular sedimentation are being observed. Forces in excess of one million times gravity can easily be obtained by such an apparatus.

During 1934–5 I collected in Plymouth Sound and neighbouring waters seven species of the genus Corophium of which two were undescribed. I also collected one other species, and had sent to me two other species (one new) from other localities in South England. A list of these ten species, with the single other species known from Britain, is given in Appendix II, and their British distribution summarized.

In the course of identifying them I examined 23 of the 32 species of Corophium, and saw all the literature to which I could find references.

The earliest detailed account of the nature of the sea bottom near Plymouth is that of Allen (1899), wherein analyses of the soils on the 30 fm. line are coupled with lists of the animals collected by trawl and dredge. Ford (1923) described a number of soils in shallower water, and gave a quantitative list of the bottom fauna, collected with a grab which covered an area of 0·1 sq. m. Smith (1932) described in great detail the soils of the area of shell-gravel which surrounds the Eddystone Lighthouse. By none of these workers, however, was special attention paid to the smaller burrowing Crustacea, which are often overlooked unless they are made the special object of collecting. Some species, e.g. of Bathyporeia and Ampelisca, may be very common, and certainly play an important part in the ecology of the sea-bottom. See Steven (1930) and Hunt (1925).

During the summer of 1935 Captain Nicholson of Saltash kindly put his motor-boat at my disposal and took me for seven full-day collecting trips on the estuaries of the Tamar and its confluents, the Tavy and Lynher. I also made some collections from land in the estuaries of the Plym and Exe (S. Devon), Taw (N. Devon), Camel (N. Cornwall), and Towy (S. Wales).

All collecting was done intertidally or in shallow water and was practically confined to the brackish-water reaches. No gear was used except a hand-net of stramin, and a zinc sieve of 1-mm. mesh. More attention was paid to the Crustacean orders Tanaidacea, Isopoda, and Amphipoda than to the rest of the fauna, observations on which were only occasionally made.

While examining a bowl of rock dredgings from the Mewstone Grounds near Plymouth, on 10th December, 1926, my attention was attracted by a handsome Phyllodocid worm which had evidently crawled out of a crevice in the broken rocks. On closer investigation the worm proved to be of an unfamiliar species and, of much greater interest, to possess a small secondary tail arising ventrally rather more than two-thirds of the way down the body (Fig. 1). Scale drawings, made at the time from the living animal, have recently been carefully checked by examination of the preserved specimen; only a few slight alterations have been found necessary.

Determinations of organic phosphorus (so called) have been made in waters from off Plymouth. The amount varies little with the time of year and averages 0·44 mg. -atom per cubic metre. This is of the same order as determinations in other parts of the North Atlantic. About one-half of this “organic phosphorus” is considered really to be arsenite.

In continuation of the three previous reports on the seasonal abundance of the pelagic young of teleostean fishes (Russell, 1930, 1935 and 1936) the corresponding data for the year 1936 can now be given. These are published in the same form as in the previous reports to which reference should be made. The dates on which the collections were taken are given in Table I and the monthly average catches for the young fish in Table II. No observations were available between October 12th and December 16th, but this does not materially affect comparison with other years because normally the young fish present at that time of year are very few in number

1. Aporrhais pes-pelecani occurs on muddy gravel at moderate depths and is specialized for burrowing in this.

2. The mode of burrowing is described and also the formation of mucuslined inhalent and exhalent openings by the proboscis.

3. There is a powerful respiratory current through the mantle cavity which also possesses three sets of ciliary currents for disposing of sediment carried in with this.

4. The animal is a specialized detritus feeder selecting only material of plant origin. The radula consists of one central and three lateral teeth on each side, an indication that it is used for seizing as opposed to scraping, not that the animal is carnivorous.

5. The stomach possesses a well-developed ciliary sorting mechanism. The large crystalline style and gastric shield indicate that the animal is herbivorous, but there is no cellulase.

Two species of Lima are known from Plymouth: Lima hians (Gmelin), the commonest species, inhabiting small patches of stones with muddy gravel at extreme low-tide mark on the north side of the Breakwater, where many individuals may be found together, and Lima loscombi Sowerby, found on the coarse grounds west of the Eddystone, Rame-Eddystone Grounds, Mewstone Grounds, Stoke Point Grounds and southwest of the Eddystone (see Marine Biological Association, Plymouth Marine Fauna, 1931). The latter is a much smaller species than the former, not so highly coloured, and much rarer. Although it is often difficult to obtain Lima hians, as it is only accessible at very low tides, it occurs in numbers in the locality cited.

1. Gonad examinations were made on monthly samples of Echinus esculentus from Plymouth in 1934, 1935, and 1936.

2. Spawning is from February–March to May, 50% spawning occurring at a temperature of 9.2–9–7° C. compared with 7.0—7.8° C. in the Isle of Man. There was a winter drop in gonad volume one year, but not the other.

3. The nature, distribution and source of the pigments in the shell are discussed, and it is shown that pigment is found in quantity in the intestine only in the summer and autumn.

4. The known facts with regard to the seasons of growth, spawning, etc., are brought together into a generalized diagram.

The Periwinkle, Littorina littorea (L.), is one of the most abundant gastropods on the shore, and can live under widely varying conditions. It is found on clean, alga-covered rocks, among small stones, on gravel, on soft mud, and rarely even on sand. It ranges from about high water of neap tides to extreme low water of spring tides, and in some places even slightly below this, although in most localities it is restricted to a much smaller part of the tidal zone. It occurs also from shores with high wave-exposure to sheltered and even polluted estuaries, where it is tolerant of considerable lowering of the salinity. The material for the present study was collected at intervals throughout 1934—1936 from three localities near Plymouth, the details of which are as follows.

During the summer of 1936 I obtained mature specimens of the medusa of Corymorpha nutans at Plymouth. An account of the early development of the hydroid reared from the fertilized eggs of these is given below. Young polyps of this species have been figured by Allman (1871) and by Hartlaub (1907). Allman found his young polyps developing apparently from the rooting filaments of the parent hydroid which had become free. Hartlaub figures and assigns young polyps which he found in the plankton at Helgoland to this species.

The process of asexual reproduction, described below, is, as far as the writer is aware, unique among hydroids. In all known species of hydroids in which an asexual bud formation has been described (e.g. in Hydra), the mouth and oral tentacles develop at the free end of the bud and the proximal or fixed end becomes the base. The sequence of development of medusa buds is essentially similar. This method applies also to budding in other Coelenterates. In the present instance the bud instead of growing out “head first,” came off “tail first,” came off “tail first” –the proximal end developing mouth and oral tentacles and the free end becoming the stalk. I can find no recoid of such a method having been described before.

The methods are described which made possible the establishment of pure cultures of a number of centric plankton diatoms and of the dinoflagellate Prorocentrum micans.

By means of a modified technique cultures were obtained of some nannoplankton autotroph flagellates varying in size from 2 to 10u. Attention is drawn to their great number in the plankton and to their importance as food in the sea.

Herring, Angler and Pilchard larvae were reared for respectively 27, 29 and 15 days after hatching. The young Herrings and Pilchards fed on Chlamydomonas sp. and Prorocentrum, the Anglers on nauplii of Artemia salina. Some evidence is given for the conclusion that the ultimate failure in rearing these species was caused by too high and variable temperatures.