1. Until the beginning of the present century there was little demand in this country for Rays and Skates. This fishery is now of major importance both nationally and within the Devon and Cornwall area.

2. Of the eleven species of Raia present in the western area of the Channel, R. clavata makes the greatest numerical contribution (37%) to the total landings in Devon and Cornwall. The composition of the catches obtained by different methods of fishing varies greatly.

3. R. clavata is the most widely distributed species in the Channel area at all depths and on all kinds of sea bottom.

4. In a series of trawl hauls off the west coast of Ireland R. clavata was most numerous in the catches down to about 100 fm. From that depth down to about 170 fm. (the greatest depth fished) R. fullonica was most numerous.

5. Unispecific and even unisexual shoals of at least three species of Raia—R. clavata, R. brachyura, R. fullonica—occur.

6. When more than one species of Raia is present within the same area at the same time, the members of the different species have been found not to mix indiscriminately.

7. R. clavata appears to hatch out in shallow water close inshore and gradually move seawards into deeper water as it grows.

8. Adult R. clavata show definite migratory movements, though the full extent of their wanderings is not yet known. There is an inshore migration in early spring of adult fish to a small part of the coast near Plymouth. The first fish to appear are females, males appearing later.

9. There is evidence of somewhat similar migratory movements by R. brachyura.

10. R. clavata—and possibly also R. brachyura and R. batis—at times may feed almost entirely on Herrings.

11. Large R. batis feed to no inconsiderable extent on other species of Eaia.

12. In foraging for their food Rays and Skates depend upon some sense other than sight.

13. There has been in recent years a steady decline in the landings of Rays and Skates from the English Channel—probably due to depletion of the available stock of fish.

The surface of most fish is covered with a coating of slime which increases in amount after death when the fish is held at room temperature or stowed in ice. The slime has been examined by Dr. Ingvaldsen of the Prince Rupert Station who has found that 3 c.c. of this material contain 33.348 mg. of nitrogen of which 11.9 per cent is amino-nitrogen. It is poor in carbohydrates, but along with the mineral salts contained in seawater it appears to provide an excellent medium for bacterial growth. In the fresh fish, the slime is clear, of mucous consistency, and shows comparatively few organisms in stained films, but in fish which are not quite fresh the slime appears to be increased in amount, is opaque and increased in consistency. With increasing age the slime becomes yellowish and evil-smelling, and stained films show an enormous increase of bacteria. In the early stages of the work attempts were made to correlate the number of organisms in the slime with the age of the fish by making bacterial counts, but owing to the irregular distribution of the slime over the surface of the fish and the difficulty of making homogeneous suspensions the results were not very satisfactory, although gross changes-were readily detected.

The paper deals with four species from the Clyde Area, namely: Tellina tenuis, Tellina fabula, Abra alba, and Cardium edule.

T. Tenuis.

1. The growth at one station below L.W.M. in Kames Bay is considered. This is slower than in any other part of its vertical range.

2. Heavy spat-falls were recorded in 1926 and in 1930, but, in both cases, the spat grew slowly and died off quickly at the stations below L.W.M.

3. The general rate of growth for the species from its upper to its lower limit of distribution in Kames Bay is tabulated.

1. An ecological survey of the fauna of Dingle Beach, Mersey Estuary, has been made.

2. A detailed analysis of the constituents of the mud, sand and gravel is given.

3. A quantitative analysis of the Molluscan fauna from a series of stations has been made.

4. Type of ground and fauna at different tidal levels are correlated.Mya arenaria is only found in abundance where there are stones. Macoma balthica is abundant wherever there is thick mud.

5. Dingle Beach is a type of Macoma community but differing markedly from the typical community described by Petersen as “d”.

6. The importance of sewage in producing silt and the part played by sewage in the food chain are discussed.

The Galatheidea are divided into two families, the Galatheidæ and the Porcellanidæ, which differ from each other in their feeding habits as well as their structure.

Galathea dispersa has been taken as typical of the Galatheidæ. An examination of the gut contents shows that the food in the stomach consists of finely divided particles mixed with sand and detritus. In addition larger pieces of animal and vegetable matter are occasionally found. Observations of the animals in captivity show that they feed by two methods; either large pieces of food are seized by the chelæ and maxillipeds and passed to the mandibles or, as is more usual, the third maxillipeds are used to collect finely divided material from the substratum.The setæ on the terminal segments of the maxillipeds form a dense tuft which sweeps over the substratum, loosening and collecting small particles. The terminal tufts are cleaned out by the setse of the second maxillipeds, and the food passed to the mouth.

Simnia patula (Pennant)=0vula is common feeding on Ahyoniwm digitatum and on Eunicella verrucosa, trawled in Plymouth waters. Mr. E. A. Todd records in the 1904 Plymouth Fauna List (Plymouth Marine Invertebrate Fauna, Journal of the Marine Biological Association, VII, 1904), which is quoted in the new fauna list (1931, Marine Biological Association), that “spawn probably belonging to this species has been found in April, June-July.” This spawn is also well known to other members of the staff of the Laboratory and it is often found with the Simnia itself. It is now quite certain that it is the spawn of this mollusc, for it has been deposited in a plunger-jar on the glass and on Alcyonium (Jan. 19/20, 1932), and hatched out Feb. 21/22, 1932; it has been hatched out in the Laboratory, the larvae distinguished in the plankton and reared until the crawling stage in a plunger-jar; and young stages which bridge the gulf from larva to adult have also been found. The adults will live for months in a plunger-jar feeding voraciously on Alcyonium. The life-history is described here for the first time. It is very interesting because it is quite unlike that of Trivia euro-pea recently described (Lebour, 1931b), although the two are placed in the same family. Trivia bites holes in compound ascidians and lays its eggs in vase-shaped capsules embedded up to the neck in the ascidian, and these hatch out into larvae having accessory shells rather like those of Lamellaria but with distinct differences. Simnia lays its eggs in a single layer of capsules, spreading over the Alcyonium for an inch or more in an irregular roundish mass (Text-figure 1).

Stilifer stylifer (Turton) has been recorded from Plymouth many years ago living on Psammechinus miliaris (=Echinus) and Echinus esculentus; also from several other British localities (see Jeffreys, 1867, IV, p. 196). Jeffreys describes the spawn and larvæ hatched from it, but apparently these have never been figured. It had not been rediscovered at Plymouth until 1931 when in August Mr. A. D. Hobson found several specimens of Psammechinus miliaris from deep water beyond the Eddystone with these small commensal molluscs on them. In the first lot of about a dozen Psammechinus, three were covered; with the spawn of Stilifer, one having one mollusc and two having two. In a second lot taken a few days afterwards, five were covered with spawn, one having one mollusc, two having two, and two having three. These were placed in a plunger-jar, but unfortunately most of the Stilifer left the Psammechinus and were presumably eaten by them as pieces of their shells were found. They probably did not like their surroundings. Some of the spawn was removed from the Psammechinus and placed in a fresh plunger-jar with some Nitzschia where some of the larvæ hatched out. A Psammechinus was introduced in the hope that the larvæ might settle down, but they all died after living only a few days.

Limacina retroversa (Flem.) has been known in the Channel for over twenty-seven years and was several times recorded by Gough (1907) and Bygrave (1911) in the plankton reports (see Marine Biological Association, Plymouth Marine Fauna, 1931, p. 265), both from inshore and from outside. In recent years the more frequent collecting in the waters round Plymouth has shown that it may be present throughout the year, although much the most abundant in summer. Not only is it found in the outside waters but it is also often present in the Sound and even at the mouths of the estuaries.

1. A study of the adult population of Sagitta elegans Verrill has been made in the waters off Plymouth by weekly collections with the 2-metre stramin ring-trawl hauled obliquely in the daylight.

2. Measurements of large samples and a study of the state of development of the gonads has shown that there were apparently four, if not live, broods of S. elegans produced in the year.

3. These successive broods were apparently spawning in April-May, June-July, and September, 1930, and February, 1931.

4. In the offspring of the September spawning population no gonads were developed during October and November. The male organs started to ripen in December, and the ovaries in January, but the brood did not appear to be fully mature until February.

The recent criticism of Thompson and Johnson (7) of the method of determining nitrate in the sea by means of reduced strychnine is held to be unsound.

Preparation of the reagent given due care and pure materials has offered little difficulty.

A possible method for the preparation of nitrate-free sulphuric acid is outlined.

The effect of iodate in concentrations likely to be met in the sea is negligible.

Interference by organic material has been avoided by first centrifuging all samples obtained during periods of plankton activity.

The relative intensity of colour given by nitrate and by nitrite nitrogen is discussed.

1. The diphenylbenzidine reaction of Letts and Rea has been examined and is recommended for use in sea-water; 2·5 ml. of sea-water is mixed with 6·0 ml. of the purest strong sulphuric acid and then allowed to cool. Subsequently 1·5 ml. of a sulphuric acid solution of diphenylbenzidine is added, the concentration being 20 mg. per 100 ml. of acid. The colour should be compared, after 20-24 hours, with a standard solution made up by adding a definite quantity of nitrate to the sea-water. A blank correction should be used. Diphenylbenzidine used must be recrystallised from boiling toluene.

2. If the sulphuric acid used is found to give a blue colour with diphenylbeniddine, this may be removed, if not too intense, by warming the acid for a few minutes. With a more intense blue the nitric acid-present may be eliminated by previous cautious treatment with hydrogen sulphide. Phosphoric acid may be used instead of sulphuric acid with fresh water, but not with sea-water.

1. On comparing the potassium ethyl xanthate and the sodium diethyldithio-carbamate methods for estimating copper the latter was found to be preferable because (a) It is at least twice as delicate, (b) The reagent is absolutely colourless, (c) In very dilute solution ferric iron causes little or no disturbance.

2. Estimation of copper may be carried out by electro-deposition from one litre of sea-water at about 90-100° C. for three hours at 2.0 volts with subsequent re-solution and colorimetric estimation using the carbamate method.

3. In agreement with the spectroscopic determinations of Dieulafait in 1879, it was found that sea-water contains about 10 mg. per cubic metre of copper.

1. A study of the adult population of Sagitta setosa J. Müller has been made in the waters off Plymouth by weekly collections with the 2-metre stramin ring-trawl hauled obliquely in the daylight.

2. Measurements of samples and a study of the state of development of the gonads has shown that there were apparently at least six broods of S. setosa during the period September, 1930, to August, 1931, inclusive.

3. The successive broods were apparently spawning in September and October, 1930, and February, April-May, June, and July-August, 1931.

The use of sodium bicarbonate for the maintenance of the proper hydrogenion concentration and bicarbonate content in marine aquaria using a closed circulation, was recommended by Breder and Howley (1). It was pointed out by them that this substance was more suitable for such purposes than quicklime which is used in the Plymouth Aquarium, because the latter “disproportionately increases the calcium content.” Atkins (2) disagrees with this opinion chiefly on the grounds that sulphates from metabolized food do not tend to increase the acidity of the water. Atkins quotes Smith (3) as stating that the urinary SO4 comes from ingested sea-water, and neglects entirely the fact that Smith had reference to the bulk of the urinary salts. As Smith remarks on page 494, a fraction of the urinary S04 is of metabolic origin, and this fraction is of course the only S04 which is significant in the problem discussed by Breder and Howley.

The contention of Breder and Howley (1931), and Breder and Smith (1932) that liming may lead to an increase in calcium in aquarium water is correct. In January, 1932, when the salinity of the Plymouth tank water was 38.0‰ the calcium content was about 0.62 g. per litre compared with about 0.39 g. found in the sea-water off Plymouth by the permanganate method. Thus compared with the normal calcium content of water of 38‰ salinity a 46% excess was present. One liming did not increase the calcium content appreciably, which suggests that the water is at the present time (Jan., 1932) saturated with respect to calcium. Other indirect evidence lends some support to this statement.

Larvæ of Nereis pelagica Linnæus were reared from the egg, and the young worms, which developed from them, to the age of one year.

The larvæ from an early stage possessed three chætigerous segments. At first after hatching they swam strongly by means of a prototroch, an akrotroch and three paratrochs, but as the cilia gradually disappeared they crawled more and more, finally abandoning swimming altogether.

The head developed a pair of tentacles anteriorly and a pair of palps ventrally. A pair of tentacular cirri arose posterior to the prototroch and a little later a second pair ventral to them.

The first pair of parapodia lost their bristles, and a lobe which had grown out between the noto- and neuropodial chæta-sacs became a third and posterior pair of tentacular cirri. Much later a fourth pair developed ventral to them.

About the time when the larvæ ceased to swim (18.days old) a fourth pair of larval parapodia (third adult pair) appeared, to be followed by a fifth, sixth, etc. At sixty-five days old worms had about twentyone pairs of parapodia, at one year they had sixty and were then about 1-5 cm. long.

During larval development a constant succession of bristles was seen. In the earliest stages the bristles were mainly homogomph spinigers with long appendices; later these fell out and were replaced by homogomph and heterogomph falcigers with shorter appendices. Later still these were replaced by bristles of the adult type.

It is pointed out that these larvæ differed from those which Herpin reared in that they hatched earlier and instead of crawling as soon as liberated they swam for several days by means of their ciliated girdles.

The Eupsammiidé are one of the most interesting families of the Madjeporaria. They have an exceptionally wide range of distribution, being found alike in temperate and tropical seas. In the latter they were probably originally confined to deep water, where the majority of them still occur, but they have extended their vertical range (Yonge, 1930) and various species are now found on many of the coral reefs in the Indo-Pacific region. Thus Dendrophyllia ramea occurs in moderately deep water in the Mediterranean and has also been found in the English Channel off RoscofE (Lacaze-Duthiers, 1897), while other species of this genus are common near the surface on many of the Pacific coral reefs, the bright orange-coloured polyps of Dendrophyllia manni being, for example, very conspicuous on the fringing reefs at Kaneohe Bay on the Island of Oahu, Hawaii (Edmondson, 1929; Yonge, 1930).

A very small, globular Echinoderm was brought to the Dove Marine Laboratory in September, 1931. Its locality of capture is not known, but it is thought to have been brought in by a child who had collected it on the local rocks. The first impression was that of one of the flatter Echinoids. Examination revealed only characteristic Asteroid features. Figures 1, A and B, are photo-micrographs of the living specimen in seawater, taken on September 16th with a 4-in. objective. The following is a description made on the same date.

The observations here recorded were made as a result of a suggestion by Professor Orton. While examining material of Psammechinus miliaris he noted the presence of C-shaped spicules in the gonad. He kindly passed the material on to me, suggesting that an examination of other common Echinoids might prove interesting.

FæecalPellets of the following species are described:—

Gibbula cineraria (Linn.).

G. umbilicalis (Da Costa).

G. tumida (Montagu).

G. magus (Linn.).

Cantharus (Jujubinus) clelandi (Wood).

Calliostoma zizyphinum (Linn.).