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.

During my researches on the vertical and seasonal distribution of young fishes I soon noticed that occasionally a specimen was found to which a Caligid copepod in an early chalimus stage was attached. As every fish caught was examined under the lens while being measured, I kept a look out for these young stages of the parasites and all occurrences were recorded. The results of this examination are given in Table I which shows also the lengths in millimetres of all the fish thus parasitised found in the collections made during 1925 and 1926 (see 1, 2, 3 and 4).

In a previous paper an account was given of the breeding and growth of Sagitta setosa throughout a year (2). The results appeared to show that the last spawning took place in October and the resulting offspring lived through November and December without maturing and that by February there were indications that a number were spawning. At the end of the following April and beginning of May a complete spawning population was formed. Owing to the large size at which these matured it was assumed (2, p. 148) that they had been the offspring of adults spawning in February. The true trend of events was however by no means clear as the increase in average size from January to May was very even (2, Plate II). There was a distinct difference at this period between S. elegans and S. setosa. In S. elegans a spawning population of individuals all about the same length was produced in February which apparently gave rise to a brood which had grown to a large size by April and May, and the change in size from February to May was much more abrupt than in S. setosa (1, Plate I). It was clear that while the February curve for S. elegans showed very little variation in size for the majority of the population caught, the population in May tended to be very widely dispersed. In S. setosa, on the other hand, there was a gradual narrowing down of the dispersion until a spawning population with little variation in length was produced by May.

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.

1. Observations are given on the vertical distribution of Sagitta elegans and S. setosa in the daytime.

2. An account is given of the seasonal abundance of both species of Sagitta throughout the year as shown by collections made with oblique hauls with the 2-metre stramin ring-trawl and hauls with a bottom plankton net.

3. An attempt is made to piece together as much as possible of the life-stories and habits of Sagitta in offshore waters off Plymouth on the basis of these and previous observations.

One hundred and twenty-one specimens of Calanus finmarchicus were anæsthetised in a dilute solution of Urethane (2·5 grms. in 100 c.c. of seawater) and the time taken by each to sink through a measured distance determined. The length of each specimen, in millimetres, was noted, and the relationship between sinking time and length of the individual was determined. The coefficient of correlation, r, was found to be —0·63.

Apstein (1910, p. 23), working with preserved material, found that the time taken by adult Calanus was less than that taken by young. He does not give actual length measurements. Eyden (1923, p. 53) showed that for anaesthetised specimens of Daphnia pulex, the average rate of fall was approximately twice as great in specimens of length 2·5–3·0 mm. as in smaller ones, whose length varied from 1·5–2·0 mm.

The position in which specimens sank was conditioned by the manner in which the antennæ were held. It was found, however, that this had not as great an influence on the sinking rate as might have been expected.

Of the 121 specimens examined, 21 were in Stage IV, 41 in Stage V; 59 were adult, of which 54 were females and only 5 were males.

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 belief for long was held by early investigators that among most if not among all Elasmobranch fishes the number of females in the stocks exceeded that of the males. As long ago as 1884 Day (4, p. 345) remarked concerning the Thornback Ray, Raia clavata, “It has been said that the number of females is in excess of that of the males.” Haacke (9, p. 246), writing in 1885, says of the Sharks and Rays which he had observed in South Australian waters, “Bei den südaustralischen Haien und Rochen, auf deren Fang ich zu wiederholten Malen ausgezogen bin und von denen mir auch nicht selten Exemplare für das Adelaider Museum zugeschickt wurden, habe ich die Wahrnehmung gemacht, dass Männchen verhältnismässig sehr selten gefangen werden. Ob diese Wahrnehmung auch anderswo gemacht worden ist, weiss ich nicht, jedoch ist es nicht unwahrscheinlich; in der mir zu Gebote stehenden Litteratur finde ich nichts darüber. Die seltenheit der geschlechtsreifen Männchen, soweit sie sich wenigstens durch die Fangresultate dokumentiert, gilt für sämtliche Species der ziemlich artenreichen südaustralischen Selachierfauna.”

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.

Records of parasitic worms from British marine fishes are still rather scanty. A good deal of attention has been paid to the subject of the Trernatodes by Nicoll, whose valuable list (1915) is indispensable to anyone working in this field. Nicoll is himself responsible for the records of the majority of the 49 species of Trematodes given in the second edition (1931) of the “Plymouth Marine Fauna.” The only work done on the Cestodes of fishes at Plymouth appears to have been that of Woodland (1927, a and b), as a result of which 14 species have been placed on record. Very few data are available as to the Nematodes, and none as to the Acanthocephala, of the Plymouth fauna.

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).

It is only occasionally that pelagic tunicates of the genera Doliolum and Salpa are recorded in numbers in the waters off Plymouth. In view of their possible use as indicators of the presence of Atlantic water (see Bowman, 1923; and Schmidt, 1909, p. 159), it is of value that their occurrence should be put on record. Regular weekly catches of plankton have been made since 1930 with half-hour oblique hauls with the two-metre stramin ring-trawl. During this period species of both genera have appeared in such numbers that it has seemed desirable to make a careful examination of the species occurring.

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.

This Autolytus has been known only in the form of Sacconereis, i.e. as the female stolon of an unknown Syllid. It was discovered in 1864 by a French zoologist, E. Claparède, at Port-Vendres (Pyrénées Orientales). According to the original figures and description it is an ordinary female individual in its general appearance, carrying a large egg-sac on the ventral side. The latter is “étranglé en 8” and turkish blue, the colour being due to the contained eggs. The body consists of about 60 segments, the dorsal surface of which is transversely banded by pigment of rose colour. Modification of the segments for swimming commences at the 9th setigerous segment and stops at the 21st. The following 40 segments (about) are not modified like the 8 in the first region just behind the head. The most striking character, by which the present stolon is distinguished from any other Sacconereis, is the presence of a pair of extra appendages in front of the head in addition to the median and lateral tentacles. Claparède states that the presence of these appendages, “qui n”ont été signalés chez aucune autre Sacconereide,” is by no means very astonishing, since there are two such ones in Polybostricus. Claparède clearly predicted their homology to the frontal lobes of the bifid antenna-like appendages in the male head. A. Malaquin (1893) actually explained the bifid condition of the frontal appendages of the male as due to their origin in the fusion of the lateral tentacles and the palpi.

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.

(1) The asymmetrical development in Hydroides opercula is due to the growth difference between two sides in the same kind of organs. The presence of a functional organ holds its mate in check. Therefore, taking off the functional operculum results in the development of the rudimentary side.

(2) This phenomenon of compensatory regulation cannot be considered to be brought about by a nervous reflex set in motion by the stimulation of damaged nerves in the operated operculum, since, for example, the inhibitory influence to a certain extent depends on the degrees of injury.

(3) It is also not proved to be due to the production of a certain chemical substance which stimulates the rudimentary organ to grow, while the wound itself affects directly the inhibitory action of the functional operculum.

(4) The inhibitory influence is only localized in the operculum and not outside of it. Therefore, cutting off the gill filaments or other parts of the body does not bring a reversal of asymmetry.

(5) Within the limit of the operculum there is no special centre of the inhibitory influence, which depends on the intactness of the internal constitution of the organ. Those peripheral parts outside the limit of direct blood supply can be cut off, without the resulting reversal of asymmetry. A simple puncturing with a fine needle also has no effect. But greater injury accompanied by an outflow of blood always starts the rudimentary organ developing.

(6) The functional operculurn has no regenerative capacity, while the rudimentary one still has. The injured operculum is thrown off sooner or later from the body, and a new start repeats from the beginning the original development. By accelerating this regenerative development of the old functional organ, or properly controlling the growth of the rudimentary organ on the opposite side, a symmetrical animal with two large opercula can easily be derived. On the other hand, if both rudiments antagonistically check each other's development, a symmetrical animal with two small rudimentary opercula is produced.

(7) Since, however, either the right or the left or even both rudiments can be made to develop into a functional organ, the inhibitory influence must act at first on both alike, unless a threshold value is assumed. In the present species of Polychsete it is as a rule the right-handed one that grows more quickly than the other.

(8) With regard to the nature of the asymmetry in Hydroides it seems to be quite different from that in the male Gelasimus in which the asymmetry of the chelas is said to be derived from the symmetrical condition relatively late in development, and the relation, once attained, becomes fixed.

(9) In Hydroides norvegica at least, the opercula show a tendency to right-handed growth from the beginning of their development, but this condition of asymmetry is very unstable and is easily reversible by an external influence even in the adult state, i.e. there is no critical stage at which it is irreversibly determined.

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.).

1. The changes brought about in the colour of the gills of rainbow trout and sea trout smolts by various poisons are described.

2. Cyanide causes a marked brightening, whilst phenolic substances, dissolved oxygen deficiency and naphthalene bring about a darkening of the gill colour. Fresh, untreated sewage has no effect.

3. The gill colour of smolts dying in the Tees Estuary was brighter than normal, indicating cyanide poisoning. This conclusion was confirmed by chemical methods.