This paper does not give a detailed description of the backbone of any one of the eight isospondylid species examined. Instead, selected data have been used in a discussion of the broad principles of vertebral variation, as seen in fishes of the order Isospondyli. This was considered to be of greater value than a catalogue of vertebral details for each of a small number of already wellknown species. Even so, sufficient has been said to enable any worker to identify the backbone of any one of the eight species, as well as to obtain a most discriminative description of the backbone of any other species of Isospondyli he may examine. A distinction is drawn between the countable vertebral characters, which are statistics for the precise measurement of vertebral variation, and the 'marker' characters, which provide the means for recognition 'on sight'. It is believed that vertebral characters of both kinds might be profitably employed in the study of different biological populations of the same species. The correlation between vertebral characters and other bodily features, such as keeled scales, position of fins and anus, and contour of body cavity, receives attention, and is related to metamerism. Finally, the occurrence of autogenus vertebral arches and the bifid condition of the neural spines in the isospondylid backbone is shown to be primitive and not restricted to the order.

1. It is suggested that the population of haddock (Gadus aeglefinus L.) on the Porcupine Bank is largely a self-contained stock.

2. This stock had complete immunity from trawling from December 1940, to September 1944.

3. In 1939 and 1940 there was an abundance of small haddock in this stock, due to the good brood of 1938. In 1944, this brood was still very abundant, and was then joined by the good brood of 1942.

4. These two good broods, growing up immune from fishing mortality, caused the Porcupine Bank to carry, in 1944, the densest stock of haddock ever experienced there.

5. The average number of sclerites in the first zone of the scales of these fish is the highest recorded in any region. It is still high in the second zone, but in the later zones falls below that found in the scales of haddock from other regions.

6. The growth rate was faster, in the first four years of life, than even that of Iceland and Faroe haddock, but in the later years it fell behind these, though still superior to the growth rate of the North Sea haddock.

7. The expectation that this greatly increased stock of haddock, due to the war-time cessation of fishing, would show a slowing in its rate of growth, due to intensified competition for the available food, is not supported by the facts.

Collections of some 22,000 female and 6000 male Crangon vulgaris were made throughout the year from the shrimp fisheries of the Severn Estuary and Bristol Channel. All animals were measured.

The habits of the species are described; it can withstand a wide range of temperature but, though euryhaline, resembles other Decapoda in the inability to withstand low salinity combined with low temperature.

Osmo-regulation is apparently largely inhibited at low temperatures and to a greater extent in the males than the females.

Growth rate decreases with increasing age; in the female there is no increase in length when moulting from the ' neuter' to the egg-carrying intermoult. The duration of this intermoult, if spawning is successful, is about double that of the normal intermoult under the same temperature conditions. Growth almost ceases in the winter.

Secondary sexual characters are described, especially the differences between the endopodites of the pleopods in the two sexes.

Females become mature at a minimum length of 45 mm. in the Channel and seldom less than 50 mm. in the Estuary. The effect of the female sexual cycle on the size of the ovary and the form of the pleopods is described. The process of copulation is described; it can occur in the brackish waters of the estuary. Egg-laying always follows within two days of moulting into the egg-carrying condition but eggs are not retained if copulation has not occurred.

The females lie on their sides during the act of spawning and the eggs are firmly attached within thirty minutes to the egg-carrying setae on the basipodites of the first to fourth pair of pleopods, then to those on the endopodite of the first pleopod, finally to those on the coxopodites of the last two pairs of pereiopods.

1. There are three herring fisheries carried on from Milford Haven, namely, a winter drift-net fishery, a spring drift-net fishery, and a trawl fishery in the summer and autumn. These fisheries provide herrings nearly all the year round.

2. There is evidence that the three fisheries are based on the same stock of herrings, and the annual migrations of these herrings, are deduced from statistical data.

3. There is a correlation between the results of the winter drift-net fishery and the following summer and autumn trawl fishery, so that it is possible to make an estimate of the prospects of the important trawled herring fishery some months in advance.

4. There is no evidence that the catches in any one season fluctuate with the moon's phases, but it is found that, in seasons when the moon was full in the last fourteen days of September, the result of the trawl herring fishery has almost always been poor.

There are various short and incomplete accounts of the capture of prey by Sepia scattered throughout the literature (Grimpe, 1928; Hertling, 1929; Holmes, 1940, are all typical and fairly recent), but I have not found any really satisfactory figures. Those I have seen are little better than rough sketches (Grimpe, 1928, p. 372; Naef, 1923, text-fig. 304b; Tompsett, 1939, plate i, fig. 2) and there do not appear to be any photographs at all. A few observations, and some photographs I have taken recently should therefore be of interest, especially as the photographs reveal some points that do not appear to have attracted attention previously. The final stages of the capture take place so rapidly that the eye fails to observe the details, whereas photographs can be studied at leisure afterwards.

The specimen of Sepia that forms the subject of these pictures was of medium size with a shell about 12 cm. long. It had been living in a tank, with others of about the same size, for several months, during which time it had been fed on living prawns. It was photographed in mid-November when the water temperature was 12.5° C. (in a later paper I shall show that below about II° C. Sepia often ceases to feed). The photographs were taken by flashlight on two evenings between 7 and 8.30 p.m., the tank being lit, for viewing purposes, by a 100 W. bulb in a reflector above one end (the left side in the pictures). Each photograph was taken at sec. with one Baby Sashalite bulb and a synchronizer of my own design, the shutter being released electrically.

A variety of Sabella pavonina Sav. described by Hornell as bicoronata has been found at Plymouth. It is characterized by the unequal development of the two sides of the branchial crown. The characters by which Sabella pavonina, its variety bicoronata and Spirographis spallanzanii may be distinguished are described. It is concluded that the genus Spirographis is not valid and that its species should be referred to the genus Sabella which is redefined.

Subjection to a variety of fluids confirms the presence of two non-living membranes roundv the developing eggs of Homarus. It also reveals that the outer membrane has the restricted permeability of cuticle and the inner membrane the free permeability of chitin.

The inner, chitinous membrane bursts when the egg contents swell; the outer membrane stretches, up to 50 % above its initial diameter, when the internal osmotic pressure rises. It also has considerable elasticity.

These properties of the outer membrane enable it to withstand the pressure to which the developing eggs are subjected and also to stretch during the development of the embryo, hence they have,considerable biological significance.The inner, chitinous membrane, which does not stretch, is probably ruptured and absorbed during development.

By the death of Lord Moyne, assassinated in Cairo on 6 November 1944, the Association has lost a very distinguished member who had contributed generously to improvements at the Plymouth laboratory and had himself made important contributions to Marine Biology. Lord Moyne had been a Governor since 1929; he was President of the Association from 1930 to 1939 and was a Vice-President at the time of his death. During the past year the Association has also suffered by the loss of Mr J. R. Norman of the staff of the British Museum, who had served on a number of occasions as a member of Council.

Four ordinary meetings of Council were held during the year, two in the rooms of the Royal Society in London, one in the Zoological Laboratory at Cambridge and one at Plymouth. At these the average attendance was II. The Association is indebted to the President and Council of the Royal Society and to Prof. Gray for their kindness in providing accommodation for three of the meetings.

The Plymouth Laboratory

During the year considerable progress has been made in the restoration of the laboratory buildings. When it became evident that enemy raids on Plymouth had ended repairs to the asphalt roofing of the buildings were carried out and the lantern light in the library was renovated, while extensive work was undertaken by the laboratory staff. Included in the latter was the replacement of numerous panes of glass in the main laboratory, the reglazing and complete internal redecoration of the library, and repairs to the constant temperature rooms.