Various biological and environmental changes that have been observed during the present century in the area of the western English Channel are briefly described, and then theories that have been put forward to account for them discussed and compared critically with one another.

At the moment, the rise in sea temperature and a possible accompanying change in emphasis of water movements offers the best explanation of all the changes. Such a theory is obviously applicable to the replacement of coldwater northern forms by warmer-water species that has taken place in many habitats (e.g. demersal fishes, pelagic fishes, intertidal zone). A decline in number of macroplankton animals, including the pelagic young of some demersal fish, can be regarded as another aspect of the temperature change, in part related to a shift in distributional boundaries, but also influenced by the replacement of herring by pilchard, which has apparently led to increased stocks of pelagic fish, and perhaps a higher level of predation throughout the year. It is suggested that the plankton production cycle may have become slightly smoother, and possibly a little more efficient, with less' wastage' to the bottom-fauna, the biomass of which may also have suffered indirectly from the increased stocks of pelagic fish.

Observations are described upon the innervation of striated muscles, the innervation of the slime glands, and the subcutaneous innervation in the hagfish, Myxine glutinosa L. It is shown that the two types of striated muscle fibre receive different types of motor innervation. Presumed sensory endings are described from above the striated muscle fibres of the ventral part of the body, and are similar to those endings near to the dorsal root ganglia whichcan be traced to their cells of origin within the ganglia. It is suggested that these endings are proprioceptive in function. Other endings within the outer edge of the myosepta are described, which may possibly also have a proprioceptive function. A rich plexus of neurons is described upon the capsule of the slime glands, and these neurons, like those of the subcutaneous plexus, receive pericellular terminations from the axons of central cells. It is suggested that they are motor to smooth muscle fibres, in the slime-gland plexus being related to the expulsion of slime (together with the action of striated muscle fibres), and in the subcutaneous plexus playing some role in the control of the venous blood in the subcutaneous sinuses.

The osmotic pressure and sodium concentration of the coelomic fluid of two species of httoral centipede have been measured and compared with those of a terrestrial one. A similar value of about 45 % sea water was obtained for all three species. Weight changes and longevity experiments in normal and diluted sea water suggest that littoral species are less permeable than terrestrial ones and it is suggested that the enlarged salivary glands of littoral species could be the site of salt secretion. A comparison is drawn with teleost and other examples whose body fluids are hypotonic to their environment.

Observations have been made on living pogonophores obtained from the continental slope to the south-west of the British Isles and from the continental shelf off the west coast of Ireland.

The blood of five species examined contains haemoglobin in solution. The tube appears to be freely permeable to water, but less so to electrolytes and small molecules.

The appearance and behaviour of living embryos is noted and the spermatozoon of one species figured. Possible feeding and other behaviour is discussed and it is concluded that the best line of future investigation lies with the shallow-water forms found in the Arctic Ocean.

The retinae of three species of deep-sea shark, Centrophorus squamosus, Centroscymnus coelolepis and Deania calcea, have been studied. All had goldencoloured photosensitive pigments, similar to those of deep-sea teleosts. The absorption maxima for the unbleached pigments lay between 472 and 484 m/n. The retina of the hake (Merluccius merluccius) was studied for comparison; its retinal pigment absorbed maximally at 495-5 mix. Some observations on the retinae of the moray eel (Muraena helena) and the Atlantic salmon (Salmo salar) are also described.

Larvae of the ascidian Styela coriacea (Alder and Hancock) were obtained by artificial fertilization and from an incubating adult. The larval cerebral vesicle has a normal otolith but no ocellus.

The results of analysis of sea water samples from the International Hydrographic Station E1 (500 02' N., 40 22' W.) are given in graphical form and as integral mean values for the water column of 70 m. Winter maximum values (in January) of 044/xg atom phosphate P/l. and 0-53^g atom ' T o t a l ' P/L, with 315/xg atom Si/1, were found. The phosphate and total phosphorus concentrations were unusually low. The spring decreases were 0-21/xg atom P/l. and 272 fig atom Si/1.

This paper lists over 100 species, mostly new records for Britain, found in the interstices of sand and shell gravel from North Wales beaches. The distribution of these species, other than the Kalyptorhynchia (Turbellaria) and the Gastrotricha, is given. The distribution of this fauna in relation to the substrate is discussed and species typical of fine-, medium- and coarse-particled substrates are listed.

In the investigation described in this paper, respiration, resistance to desiccation and feeding behaviour of .the mid- to upper-tidal isopod Campecopea hirsuta was studied and compared with the analogous parameters of behaviour in the lower intertidal species Naesa bidentata

C. hirsuta occurs in the middle part of the shore where it can be found within empty shells of Chthamalus. Its preferred habitat, however, is the lichen Lichina pygmaea the vertical distribution of which extends from OD to MHWS.

Campecopea hirsuta feeds on the blue-green algae that make up the outer layer of the lichen L. pygmaea. When continuously submerged the isopod feeds in bursts, the timing of which is different in different specimens. This mode of feeding under experimental conditions is taken as reflecting the rhythmic way of life of this species in its natural environment but it seems to be controlled by endogenous factors. Naesa bidentata, on the other hand, does not display such endogenous rhythms in its feeding behaviour.

Two species of wrasse, Ctenolabrus rupestris (L.) and Crenilabrus melops (L.) were experimentally infected with the digenean Proctoeces subtenuis (Linton) collected from Scrobicularia plana (da Costa). The fishes were killed 1-24 days after infection, and the parasite population of their guts examined. About 20 % of the introduced parasites survived for 2-3 days, but the degree of infection decreased with time, the smallest specimens surviving longest. No significant differences were found between parasites from invertebrate and experimental vertebrate hosts.

P. major Yamaguti, 1934, and P. insolitus (Nicoll, 1915) are declared synonymous with P. subtenuis (Linton, 1907

The bearing of these results on the life cycle of P. subtenuis is discussed

It has been observed that the pH in the different parts of the alimentary canal of Corophium is nearer neutrality; while the medium in the ventral hepatopancreatic caeca is more acidic, being in the neighbourhood of 6.2.

Investigations on the qualitative estimation of enzymes indicate that none of the enzymes are secreted by the gut proper. However, the ventral caeca only secrete many of the carbohydrate splitting enzymes; proteases and lipase are also secreted by the caecal cells of Corophium

It has also been estimated that the optimum pH for the activity of the caecal amylase lies in the neighbourhood of 5.8.

A method of determining the age of Laminaria hyperborea by examination of a longitudinal median section of the lower stipe and holdfast was found to be reliable for at least the first 4 years.

Photographic recording at hourly intervals of a group of animals contained in a small tank kept in continuous darkness has revealed a 24 h cycle of locomotor activity in Daphnia magna and in Calanus helgolandic

A change in periodicity of the rhythm in Daphnia kept under continuous illumination suggests that the cycle is not determined by external stimuli

The phasing of the cycle differs in the two animals, but in both there is an increase in activity during the hours of darkness.

In Calanus and possibly also in Daphnia, the cycle of activity is absent in the winter months.

Blood from Arenicola marina has been shown to contain an active catalyst of sulphide oxidation. This activity is associated with the respiratory pigments. Purified native haemoglobin and oxyhaemoglobin from this animal have similar activity in this respect to the analogous mammalian respiratory pigments and to mammalian hemiglobin. The oxidation product of Arenicola haemoglobin (the brown pigment) which is formed under conditions which might be expected to produce a hemiglobin is, in contrast, a very active catalyst of sulphide oxidation.

This paper is concerned with the number of eggs in the roes of ripening female plaice, Pleuronectes platessa L., caught off La Rochelle during the winter of 1960–61. The fecundity of plaice has been studied over a number of years in fish collected over a wide area (Bagenal, 1958,19600,6,1962) and the results given in this paper apply to plaice caught as near the southern limit of their distribution as possible. Although plaice have been recorded from farther south (Wimpenny, 1953), La Rochelle is the most southerly port where they can be obtained in sufficient numbers.

This paper is one of a series on the fecundity of the plaice Pleuronectes platessa L. over a wide area of its geographical distribution and is concerned with the number of ripening eggs in the roes of female Icelandic plaice prior to spawning (see Bagenal, 1962, for references to other areas).

Thirty-eight plaice were caught by the Icelandic research vessel ‘Maria Julia’ on 23 and 24 March 1961 in the Midnessjor area. They were measured and weighed and the otoliths were extracted. The ovaries were preserved in modified Gilson's fluid (Simpson, 1951). I am very grateful to Mr Jon Jonsson who kindly made all the arrangements and Mr Gunnar Joakimsson who prepared the material in Iceland. The fish were very ripe and a few had developed translucent eggs, but spawning had not begun. The subsampling and statistical treatment of the results were the same as before (Bagenal, 1962). The otoliths, after being kept dry, were very difficult to read.

The Icelandic plaice are an isolated population, separated by deep water from the rest of Europe, and there are several spawning areas. currents move clockwise round Iceland and will carry the fertilized eggs and young larvae from Midnessjor and the S.W. coast spawning areas (Thomsen, 1948) to the good nursery grounds of Faxa Bay. Tåning (1929, 1948) has given accounts of the Faxa Bay plaice biology and suggests that ‘the eggs and tiny fry, which are found in the Bay in the spring months, seem mainly to come from the outside, for the greater part most probably from S.W. Iceland’. The eggs from the population offish considered in this paper, from Midnessjór, would drift into Faxa Bay which forms a good nursery ground.

The seasonal changes in the body weight and composition of two common boreo-arctic species of cirripedes, Balanus balanoides and B. balanus have been followed.

At a constant size (age under constant growth conditions) the body weight is closely related to the season. Increase in body weight takes place rapidly during the spring as reserves are laid down. These reserves are subsequently utilized for gonadal development.

The changes in B. balanus are more gradual than in B. balanoides and probably reflect differences in the habitat conditions.

The reserves, although contributing to the gonads, are not themselves adequate for their total tissue.

There is some reduction in oxygen uptake of isolated bodies on starvation when carbohydrate is being utilized.

There is a gross discrepancy between the oxygen demand as measured in isolated bodies and the available substrate; respiration is probably reduced during inanition.

It is suggested that the moulting cycle is coupled to the metabolic activity in an obligatory fashion rather than being dominated by the kind of hormonal control found in decapods.

The entire cell surface, including the flagellar surfaces, of three species of Pyramimonas and of two different strains of Pyramimonas-hke zooids of Halosphaera are shown to be covered with scales in at least two layers, namely, an underlayer of very small scales arranged directly on the flagella membrane or plasmalemma and one or more outer layers of much larger scales of different character. On one and the same cell the shapes of the scales of all layers are different on the flagella from those on the body. Among all the taxa studied the flagella scales are very similar but those of the bodies are specifically differentiated; details are illustrated in the plates. In two taxa {Halosphaera and Pyramimonas amylifera) the outer scales on the flagella have been shown to be consistently arranged in 9 longitudinal rows; numerical information is not available for the other taxa studied but they are not expected to be different. The presence of an unusual type of flagellar hair has also been noted though those have not yet been studied in detail.

The interstitial archiannelid Trilobodrilus heideri was found to be photophobic, fairly tolerant of low salinities and responsive to water current. This latter response of orientation and progression toward a water source was gradually lost by specimens suddenly transferred to low salinities. Rhythmic gregariousness was shown to occur in this species. The relation of this rhythm to tidal factors is postulated. It is shown how the demonstrated responses may affect the position occupied by T. heideri on the shore