In a collection made with a 2 m stramin ring trawl at 47°03′ N., 5° 47′ W. on 4 July 1956, with 800 fathoms of wire out, I have found a new species of medusa. This specimen is in a comparatively good state of preservation except that the stomach is badly damaged.

The umbrella is hemispherical and the jelly is moderately thick. The form of the stomach cannot be described for certain. Parts of it are to be seen as narrow strips hanging down from the upper ends of three of the radial canals. One of these strips is continued for a short distance along the subumbrella surface towards the summit. It has the form of two short curtains with a space between them which leads into the radial canal. It thus seems quite possible that the stomach is i n fact an open cross with mouth lips extending along each arm as in Staurophora.

The adults of three new cyclopoid copepods are described and figured, namely Micropontius ovoides, gen. et sp.nov., occurring on spatangid echinoids; Lichomolgus leptodermatus, sp.nov., and Conchyliurus cardii, sp.nov., both associated with pelecypod molluscs. Micropontius is made the type of a new family, the Micropontiidae.

Some other copepods, Asterocheres violaceus (Claus), Scottomyzon gibberum (T. & A. Scott), Pseudanthessius liber (Brady & Robertson), Bomolochus confusus Stock, Euryte longicauda Philippi var. minor T. Scott and Peniculus fistula Nordmann, are recorded for the first time from the Plymouth region; and mention is also made of Tisbe elongata (A. Scott).

Points of interest in the biology, morphology, systematics and distribution of all these are discussed.

Some features of the organization of the endostyle of Ciona intestinalis are described. Autoradiographs show that bound iodine is present in a limited area of the epithelium (zone 7), where it is associated with characteristic secretory inclusions which are found only in this zone. These are regarded as providing the molecular basis for the iodination process, and are termed 'thyroidal granules', since they resemble in certain properties the similarly named granules of the endostyle of the ammocoete; it is concluded that they are homologous with these and, through them, with thyroid colloid. Their existence provides evidence that the iodination process is a product of biochemical specialization, and implies that it results in the formation of an hormonal secretion. It is concluded from the distribution of bound iodine over the pharyngeal epithelium and in the food cords that this iodinated secretion is carried in the latter into the intestine. Bound iodine is also present in the cuticle of the test; it is suggested that this may differ from the situation in the endostyle in being a consequence of the iodination of a skeletal protein secretion such as is known to occur in many invertebrates. Prior immersion of the animals in thiouracil solution largely eliminates bound radio-iodine from all of the sites mentioned, although a little may sometimes be detectable in the food cords and cuticle. The results are discussed in the light of recent work on Amphioxus and the ammocoete larva, and attention is drawn to their bearing on current views on the relationship between vertebrates and protochordates.

The disappearance of mercury from stored sea-water solutions of mercuric chloride has been studied by means of the chloroform-dithizone procedure and by the use of radioactive mercury (203Hg).

When sea water is enriched with nutrients facilitating the growth of bacteria, the rate at which mercury is lost from the solution is markedly increased. On the other hand, when the sea water is treated in various ways which prevent the development of bacteria, the loss of mercury from solution is considerably reduced.

Rates of loss of mercury measured by the chloroform-dithizone procedure and by the use of tracer isotopes are in good agreement only in the early stages of the experiments. Thus, at a time when approximately hah0 the mercury has been lost, titrations with chloroform-dithizone only account for about 50% of the mercury determined by measurements of radioactivity. Further findings have suggested that this discrepancy arises from the fact that a considerable amount of the mercury is taken up by bacteria and converted into a form which is not detectable with chloroform-dithizone.

The apparatus described in this paper was constructed for the purpose of sampling the zooplankton standing crop in the ocean in a quantitative manner.

A meter is described, which will record both the depth and amount of water which a net filters as it is hauled vertically through the water. The meter records on a smoked glass cylinder.

The meter is mounted in a brass drum which is positioned in front of the silk filtering section of the net. In front of the meter a long canvas sleeve carries the throttling rope which closes the net by the Nansen method.

Calibration of the meter for depth is done by using reversing thermometers and lowering to a series of suitable depths. Flow calibration is easily accomplished in the field by towing the canvas sleeve and meter without the silk net.

The method of smoking the glass cylinders and taking photographic records of them is described.

From the records it is possible to study the complete behaviour of the net below water—what depth range it has fished, how much clogging occurred, the depth of closure, etc

Recently Jones & Wills (1956) have related the attenuation of light in the sea and in estuarine waters to the concentration of suspended solid matter. The attenuation was measured with an in situ hydrophotometer with a beam acceptance angle of approximately 3.20°. The concentration of suspended materials was determined by filtering in the case of natural samples or by adding known weights of kaolin or mud to tap water. In the discussion of their data and methods they have made application of the difFraction theory for opaque particles relatively large compared to the wave-length of light.

A study has been made of the toxicities of mercuric chloride, mercuric iodide and methyl-, ethyl-, n-propyl-, n-butyl-, n-amyl-, iso-propyl-, iso-amyl- and phenylmercuric chlorides to larvae of the crustaceans Artemia salina and Elminins modestus. With both species it has been found that all the mercury compounds are more toxic than mercuric chloride, that primary alkylmercuric chlorides are more toxic than the corresponding secondary compounds, and that as the homologous series of primary compounds is ascended, toxicities increase. In addition, it has been found that Elminius is much more readily poisoned than Artemia by each mercury compound, and that differences between the toxicities of the poisons to Elminius are much smaller than corresponding differences observed in experiments with Artemia.

Mytilus galloprovincialis Lmk. is recorded as dominating the mussel population on the north coast of Devon and the north and south-west coasts of Cornwall from Instow to the Lizard. It was also found less frequently on the coast of South Wales from Angle to Cardiff and on the south coast of Cornwall from the Lizard to Plymouth.

The chief distinguishing features of M. galloprovincialis from Cornwall are summarized, in comparison with M. edulis L.

M. galloprovincialis is apparently intolerant of estuarine conditions, but otherwise appears to be ecologically similar to M. edulis.

M. galloprovincialis is not resistant to infection by Mytilicola intestinalis, but appears to be less affected by the parasite than is Mytilus edulis.

The synonymy of the species is briefly discussed and it is concluded that, although earlier workers tended to confuse M. ungulatus L. (recorded also as M. ungulata and M. angulata) with M. galloprovincialis Lmk., the two types are distinct. M. ungulatus is a name of doubtful validity applied by Linnaeus to a distorted form of M. edulis.

A comparison is made of oxygen and phosphate data from the Fladen Ground. It is found that the conversion factor for oxygen:phosphorus given by Sverdrup et al. (1942) does not agree with the changes below the euphotic zone and an alternative factor is calculated. Problems concerning surface exchange and production are also discussed.

Growth-rings on the shell of the scallop (Pecten maximus) are laid down annually, in spring, and so can be used to determine the age.

Scallops grow from spring to December, and cease growing in winter. The resumption of growth in the spring is marked by the appearance of the annual growth-ring at the edge of the shell.

The first year's growth is of one of two types. A few scallops have shells which show a large first year's growth, 28 mm or more wide, while the great majority have shells which show a small first year's growth, less than 28 mm wide. These two types probably depend on the two principal spawning periods of the scallop, most of the former arising from the spring spawning and most of the latter from the autumn one.

The growth curve of P. maximus is of a type characteristic of lamellibranch shells. The annual growth is greatest in the first two or three years of life, after which it decreases steadily.

Scallops grow more quickly in shallow water than in deeper water.

Possible causes of the annual cessation of growth are discussed.

A paucity of young scallops was noted in the dredge samples, as previous workers have reported. No reason can be given.

Organic production in the sea can be measured by studying the changes in phosphate throughout the water column. Results obtained by this method are compared with estimates of carbon uptake using 14C made on the Fladen Ground during 1955 and 1956. There is good general agreement between the two methods but some differences in the vertical distribution.

The results are also used to calculate filtering rates of phytoplankton and sinking rates of zooplankton, and to compare observed and predicted vertical distributions of chlorophyll.

Populations of Scrobicularia plana with densities up to 1025 per m2 are found in the Gwendraeth Estuary.

In a region where the population density was about 500 per m2 it was found that some specimens lived for 16‐18 years and reached a length of 54 mm. An approximate growth curve is given.

There is very little successful settlement of spat in the sampling area; less than 2% of the shells were under 10 mm in length in July 1955. This low figure is attributed to the feeding activities of the dense adult population making the area difficult to settle in.

Techniques for the rearing of monogenean larvae are described.

The new term ‘oncomiracidium’ is proposed for the larvae of monogenetic trematodes.

Eleven new oncomiracidia offish parasites are described, bringing the total now known to thirty-five.

These oncomiracidia are tentatively classified, and the classification is compared with the existing classification of adult monogeneans.

Observations have been made of the surface currents off the Northumberland coast over a period of 12 months, using a free-floating buoy. A mean vector current was found, setting 114° at o·i knot. Currents flowed into the quadrant to the right of downwind except when this would have directed them ashore. A relationship is established between wind speed and current speed.

During 1952–54 a survey was made of the Polychaeta living in the offshore bottom deposits of the south of the Isle of Man. These deposits range from stones and coarse gravel to soft mud; samples were obtained with a van Veen grab sampler and various dredges.

It was found that, although some species were widely distributed, each bottom deposit had a typical fauna, and that where the deposits graded into one another the polychaete fauna was also mixed. The distribution of each species appears to depend mainly on its mode of life and feeding habits; some can exist in several types of deposit or habitat, while others are very much restricted in their distribution.

The Polychaeta formed a high proportion, numerically, of the macrofauna, exceeding any other animal group, except possibly in the coarse gravels. However, the density of the polychaete population was low compared with other areas of the British Isles, and this may be correlated with the comparatively low biomass in the area.

Elytra of polynoids show two kinds of luminescent responses, viz. a quick flash (duration ca. 100 msec) and prolonged glow (duration 0·25–10 sec). Quick flashes are produced by nervous excitation; prolonged glow responses accompany or follow fast repetitive flashing, or are elicited by strong electrical stimuli. Anaesthetized isolated elytra still give the prolonged glow response when electrically stimulated. Facilitation is also evident in consecutive glow responses. From these various observations it is concluded that the prolonged glow response can be produced by fast repetitive nervous excitation or by direct electrical excitation of the photocytes. The occurrence of facilitation in glow responses of anaesthetized elytra raises the problem whether the same phenomenon in consecutive normal flashes may be due to intracellular changes taking place within the photocytes.

In a sample of over 1000 rays belonging to four species of Raia examined at Plymouth between May 1955 and August 1956, the ‘very rare’ monogenetic trematode Dictyocotyle coeliaca Nybelin, 1941 (total of four previous records) was found in the coelom of thirty-five out of 135 specimens of Raia naevus but absent from 478 R. clavata, 420 R. montagui and 34 R. brachyura.

Vitamin A and carotenoids were measured in six species of Penaeidae and seven species of Sergestidae.

Vitamin A was present in at least one sample of all species except Gennadas borealis at concentrations mostly of the same order as previously found in other Decapoda, but usually higher in the Sergestidae than in the Penaeidae.

Carotenoids in the Penaeidae included astaxanthin and its esters, carotenes and xanthophylls, but only astaxanthin or its esters with occasional traces of xanthophylls were found in the Sergestidae.

Owenia may feed either by ciliary means or by swallowing sand and detritus. The gut consists of three main parts, a fore-gut or stomach which is secretory, a non-secretory mid-gut region which is absorptive, and a hind-gut which is non-secretory, non-absorptive and serves to elaborate and store the faecal pellets. The mid-gut contains coproporphyrin III and also phaeophorbide-6, to which the green colour is due. The green pigment in the epidermis is also phaeophorbide-ft, but phaeophorbide-a is apparently absent from the body.

Luminescent polynoids emit light from their elytra. These structures are arranged in two longitudinal rows covering most or all of the dorsal surface of the worm. Light emission is evoked by stimulation and appears as a single flash or series of flashes (Nicol, 1953, 1957).

When a polynoid is subjected to tactile stimulation, scales anterior and posterior to the stimulated region emit flashes. The response is a reflex, the excitatory pathways of which involve peripheral receptors, nerve cord, and a peripheral ganglion in each elytrum on the efferent side of the arc (Bonhomme, 1942; Nicol, 1954).