1. Church Reef, in Wembury Bay, near Plymouth, was selected for a survey of common intertidal plants and animals.

2. Four traverses were accurately levelled relative to Ordnance Datum, and their floras and faunas examined.

3. The relation between predicted tide levels and probable actual levels is discussed, and the importance of the “splash zone” is stressed.

4. As an outcome of 2 and 3, it appears that on Church Reef the most critical levels on the shore, for the species examined, are: (a) between Mean and Extreme Low Water Springs; (b) between Mean Low Water Neaps and Springs; (c) at Extreme (Lowest) High Water Neaps. The least critical level is Mean Low Water Neaps.

5. Two special problems are presented by the upper limits of Littorina saxatilis and L. neritoides, and by the frontiers between Ascophyllum and Fucus spiralis and between F. spiralis and Pelvetia, where the algæ do not overlap.

6. The work of previous authors is discussed for comparison with the present paper.

7. An important difference is suggested between the nature of the zonation of sedentary animals and plants on the one hand, and that of animals capable of locomotion on the other hand.

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 two forms of Trivia which are recorded from Plymouth (Marine Biological Association, 1931) have hitherto been regarded as one species (Trivia europea), but recent researches (Peile, 1925; Pelseneer, 1932) have shown them to be distinct. Peile calls the two species Trivia monacha (Da Costa), with the spotted shell, and Trivia arctica (Montagu), with the unspotted shell. Pelseneer calls them respectively Cyprœa (Trivia) europœa L. and Cyprœa (Trivia) arctica Montagu. A closer investigation at Plymouth fully bears out the conclusion of the above-mentioned workers that there are two species and the fact, brought forward for the first time in the present paper, that the larvæ are also distinct makes the determination doubly sure.

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.

Nothing is known of the life-history of Erato voluta (Montagu)=Erato lævis (Donovan) and in the following note the larvæ are described for the first time. Erato being very closely related to Trivia, it was to be expected that the larvæ would be somewhat similar, but, although there is here, as in Trivia, an Echinospira larva, the details of its life-history are quite different and the accessory shell when fully developed differs much from that of Trivia.

The life-histories of the two species of Cerithiopsis are described here for the first time, that of Triphora perversa is partly known already. All three species are common in Plymouth and their larvæ are very common in the plankton in spring and summer. Pelseneer (1926) has described the eggs and newly-hatched larvæ of Triphora perversa from the Brittany coast and Fischer (1884) has noted that it has a very long free-swimming life, still being a veliger with up to 7 or 8 whorls. The eggs of Cerithiopsis barleei have now been found at Plymouth and the larvæ reared as far as a stage just before settling down, the late stages from the plankton being reared to the crawling stage in plunger-jar. The eggs of Cerithiopsis tubercularis have not yet been seen, but the larvæ are common in the plankton and the late larvæ have also been reared in a plunger-jar until the crawling stage.

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.

Nothing is known of the eggs and larvæ of Turritella communis and, except for the young shells which have already metamorphosed, those of Aporrhais pes-pelicani are also unknown. The following descriptions are therefore new, both molluscs having been kept in plunger-jars until they laid their eggs.

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).

The genus Philbertia, belonging to the family Turridæ, is well known to have the larval shell beautifully sculptured and, as it is retained as the apex of the adult shell instead of being knocked off or concealed as is the case with many gastropods, it is easy to identify as belonging to this group, the veligers also reaching a large size and being conspicuous in the plankton.

1. Artificial fertilisations of Notomastus latericeus Sars were made and the larvæ reared.

2. The two-day old trochosphere is provided with a large central mass of yolk. It has a broad prototroch, a telotroch, a neurotroch and an apical tuft. It swims rapidly.

3. Development consists in the appearance of trunk segments; The most anterior of these is the achætous peristomium. Those following acquire neuro- and notopodial chætæ.

4. At an age of about ten days the cilia are gradually lost. The larva then has about five chætigerous segments, the first three bearing bristles, the last two hooded hooks.

5. The young worms lived for some twelve days after metamorphosis and by that time had seven clætigerous segments. Only a little of the yolk still remained. The worms possessed a protrusible introvert and were feeding on diatoms.

6. The larva apart from its strong prototroch and rapidity of swimming does not exhibit any special structural adaptations to pelagic life, such as are found in some other Polychæte larvæ. In comparison with Capitella it has fewer segments when it metamorphoses.

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.

The Notodelphoidea are a heterogeneous collection of copepods which are found parasitic within urochordates and there is considerable doubt as to the exact systematic position which should be occupied by this group. It comprises—in the sense in which it is used by Sars (1921)—six families of excessively doubtful affinities in that there are grouped together Copepods (1) which brood their eggs (Notodelphys, Doropygus, etc.), (2) others which are possessed of elongate egg-strings (Entericola), (3) and others which deposit their eggs singly (Mycophilus). Now it appears to the present writer that such great variation in habit must argue an equally great variation in the structure of the genital organs, for the “cement gland” and “hardening gland” (see Gray, 1928) may be presumed to be absent if egg-strings are not formed. It is doubtful, therefore, whether any useful discussion on the classification of these forms can take place without a parallel and detailed investigation of the internal anatomy. There is, however, another line of approach—the study of larval forms. It is equally as a preliminary skirmish along this line of attack, and as a contribution to our knowledge of larval forms, that the present brief note is presented.

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.

The notodelphoid copepods parasitic within Ascidians have been generally ignored for a long time. In May 1932 the present writer collected a considerable number at Millport Marine Biological Station, and was amazed at the frequency with which they occur. It may be that the Clyde area is especially favourable to their development, or it may be that the season was particularly good, for about thirty specimens were collected of ten species, of which at least one—the subject of the present paper—was new to science. If this abundance of forms is indeed usual, it is difficult to understand why records are not more frequent, and it would be interesting to learn how frequently these fascinating and aberrant forms are lost in the course of class dissections of their hosts.

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.

In recent years the development stages of Copepoda have been the subject of study by various workers. Their attention, however, has been mainly directed to fresh-water species, presumably because the material is more readily available, and it seems desirable that our knowledge of the development of marine Copepoda should be extended. The material utilised for the present work was collected on the periodic and comprehensive fishery cruises carried out by the F.B.S. Explorer, and we are indebted to the Fishery Board for Scotland for permission to undertake this detailed study. Since the appearance of Grobben's standard work on Cetochilus septentrionalis Goodsir (Calanus finmarchicus Gunn.), the only important publication dealing with the life-histories of marine Copepoda, so far as we have been able to ascertain, is that of Oberg, who, in Die Metamorphose der Plankton-Copepoden der Kieler Buclit, describes the development stages of seven common marine forms. Oberg's choice of species, which are all more or less neritic, was again obviously dictated to him by the material at his disposal, and it is hoped that our collections, which cover not only the northern part of the North Sea, but also the Faroe–Shetland Channel, and part of the Atlantic itself, will furnish material for the establishment of the life-histories of some of the more oceanic forms.

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.