1. In the course of three trips to the herring grounds in the vicinity of St. Ives five seals were sighted. Seven others were also seen at various other times and places in the course of five days spent in that locality.

2. During a single night at sea in Port Isaac Bay eight seals were sighted.

3. It was obvious from the movements of certain of the seals observed on the fishing grounds that they were attracted to the herring nets.

4. Direct evidence that the seals actually remove fish from the nets was not obtained.

5. Damage done to drift nets by seals is negligible.

6. Grey Seals (Halichœrus grypus) are present in considerable numbers, and are probably the commonest seals in Cornish waters.

7. Brown Seals (Phoca vitulina) appear to be few—they may even be rare—around Cornwall.

8. There is at least one seal colony of considerable size in certain caves near Boscastle. This appears to consist of Grey Seals. Probably other such colonies exist on the Cornish coast.

9. Clupeoid remains have been found in two out of the three Grey Seal stomachs which have been examined.

10. Further and more exact knowledge of the habits and relative abundance of Grey and Brown Seals around the Cornish coast is desirable.

1. Details are given of the types of hooks lost in tunny in the North Sea in the summer of 1933.

2. Data are given on the measurements made on thirty-two large migrating fish caught in the North Sea in August and September, 1933.

3. In certain body proportions the tunny measured differ from those in the G4 Group (200 to 260 cm. in length) given by Heldt for fish from Tunis and by Frade for fish from Algarve on the south coast of Portugal, while in some characters they resemble the Tunis fish and in others the Algarve fish, but all the North Sea fish were between 232 and 271 cm. in length.

4. It was found that there was a tendency for fish with short second dorsal fins to have short first dorsal, anal, and caudal fins, and for those with long second dorsals to have these other three fins long.

5. Measurements were made to supply data on the condition of the fish.

The free-swimming young of the Rissoidse are particularly important in the plankton for there is always one or more species present in any month and they usually occur in great abundance. The various species live between tide-marks, in the laminarian and coralline zones and in deeper water in several fathoms depth; wherever tow-nettings are taken they usually contain some species of this family. The inshore waters, however, are the richest in rissoids. Even in winter certain species are common round the Plymouth coasts. Some years ago it was found that very young herring just before losing the yolk-sac and about a fortnight old had been eating small rissoids, evidently almost newly hatched (Plate I, Fig. 1). The herring up to a length of about 12 mm. and just after the yolk-sac had disappeared altogether continued to eat them but usually after this size they ate only small Crustacea. From 1917 to 1921 it was found that out of 140 young herring examined, 91 had fed on these small gastropods. In later years they were also found feeding on them (Lebour, 1921, 1924). Other minute planktonic organisms were eaten, including algæ, tintinnids, copepod and cirripede nauplii and very small adult copepods; also a minute bivalve larva but no other gastropod, although other veligers were present in the plankton, Patella being specially common. The young herrings hatch out from December to February, therefore these little gastropods must also hatch at this time and this proves to be the case for in the plankton there are large numbers of these very young veligers (Plate I, Figs. 7–8). Later on, in spring, older stages of the same mollusc abound and are quite the commonest veligers in the plankton near the coast (Plate I, Figs. 17–19). In the summer they have almost entirely disappeared.

In a previous paper (Lebour, 1933) the eggs and larvæ of Philbertia (Comarmondia) gracilis were described, showing lens-shaped sessile eggcapsules and a planktonic larva with elaborately sculptured shell and large brightly spotted velum, which remained as a veliger until it had attained several whorls and was of a large size before metamorphosis. Lens-shaped capsules are apparently typical of the group (Jeffreys, 1867, and observations at Plymouth) and finely sculptured embryonic shells with several whorls are already known in many species (Jeffreys, 1867; Cossmann, 1895; Thiele, 1929). Researches in the Plymouth plankton show that members of this family are common and are some of the largest and most conspicuous gastropod larvæ. They are therefore of considerable economic importance in the sea.

In 1892 Cunningham described a new species of Siphonophore, Muggiœa atlantica, which was first noticed by him in the waters of the English Channel off Plymouth in the autumn of 1891. Since then there have been records from time to time of the occurrence of this species at Plymouth (see Plymouth Marine Fauna, 1931, p. 84), and its distribution in the English Channel and Irish Sea in 1904 was worked out by Gough (1905).

1. Twenty oblique hauls of a stramin ring-trawl, diameter of mouth 5 feet, were made during a period of 48 hours off Liverpool, Nova Scotia, i n May, 1932.

2. The common species were Thysanoëssa mschii, Th. inermis, Sagilta elegans, Calanus finmarchicus and C. hyperboreus.

3. All of the above occurred in the collections made during the night n i larger numbers than in those in the daytime. No such discrepancy appeared in the case of the Fish Ova.

4. The discrepancy is held to be due in each case to a proportion of the population sinking to depths greater than could be sampled by the net.

1. Observations are given on the vertical distribution of adult Calanus finmarchicus in the daytime off Plymouth in July and August, 1931, as a result of collections made simultaneously with the photo-electric measurement of submarine illumination.

2. A series of nets, usually six, was towed simultaneously in such a manner that the depth of each net was known approximately.

3. The female Calanus in July preferred higher intensities of light than did the females in August; this change was coincident with a change in the Calanus population as shown by size measurements. A similar change in distribution and in population was shown by the males.

4. The females in July were living in intensities of 20,000 m.c. and more; but those in August were avoiding such high intensities. The males in July avoided intensities of 40,000 m.c. and over, while in August their upper limit was about 10,000 m.c.

1. The present paper deals with changes of biomass and size of Calanus finmarchious throughout the year the Plymouth area.

2. The material was supplied by regular oblique hauls during 1930; Stage V and adult males and females having been examined. Calanus finmarchicus occurred throughout the year reaching its maximum value in May, being abundant from the middle of April to the middle of September.

1. The dry weight of 100 male, female and Stage V Calanus in Loch Fyne fluctuated throughout the year. 100 Stage V Calanus in May weighed only about ⅓ of what they did in December. Male and female Calanus also fluctuated considerably in weight.

2. Stage V Calanus is usually largest and heaviest when it is most abundant. With male and female Calanus size and weight are related.

3. Stage V Calanus, in spite of being smaller than female Calanus, was from the beginning of June till the end of August considerably heavier (over 100%). When Stage V Calanus was at its lightest and smallest, it weighed less than female Calanus at the same time.

4. The weight of Stage V Calanus fell during the spring and did not increase again till after the end of the first breeding period.

5. The fat and protein content of Calanus depends chiefly on dry weight. The values obtained for fat content were considerably higher than those hitherto recorded for zooplankton and those of protein lower.

6. The ash content is about 3·6% and the chitin content about 3% of the dry weight.

7. Stage V Calanus accounted for by far the most important part of the total weight of the catch throughout the year.

8. The total food value of the Calanus in Loch Fyne probably varies very considerably from year to year.

1. The development of Scolecolepis fuliginosa (Claparède) is described from the egg to the young worm for the first time.

2. Comparison of reared larvæ with larvse from the plankton did not reveal any important difference.

3. The eggs are pelagic, and are similar to those of Nerine.

4. A description is given of the histological structure of a ciliated pit which arises in early larval existence and disappears at metamorphosis. The structure of the glandular region of the pygidium is also described.

5. It is apparent that from the attainment of the fourth setiger onwards, the centre of differentiation is located in the third setiger, so that segmental structures arise first in this segment and then appear in the first and second setigers as well as in the succeeding ones.

6. The larva of Scolecolepis has three pairs of eyes, the third pair disappearing in the young worm long after metamorphosis is otherwise complete.

Laboratory experiments indicate that larvæ of Scolecolepis fuliginosa when ready to metamorphose, are able, if necessary, to postpone metamorphosis until a substratum suitable for adult life is reached, meanwhile continuing to swim and grow for a period that may be as long as several weeks.

Procerodes ulvœ has been found living in streams with calcium content as low as 5 mgm. per litre. Its upper limit does not appear to be affected by the calcium content of the water. The animals at the upper limit are liable to about 5 days' exposure to fresh water if calm weather coincides with Neap Tides. Animals living in water of 8–12 mgm. Ca per litre have been found alive at the end of such a period.

In view of the serious mortality reported among Cardium edule in the summer of 1933 (Orton) the following account of British parasites of this species may be of interest.

1. A diving helmet can be used successfully on British coasts.

2. An ecological survey, extending to a depth of 10 feet below low water of ordinary spring tides, has been made of a small area in Wembury Bay, S. Devon.

3. Below low water of ordinary spring tides upward facing rock surfaces were occupied by a “Laminaria forest association.”

4. Below L.W.O.S.T. vertical or overhanging rock surfaces were occupied by a “Distomus-Halichondria association.”

5. Large brown Algæ are excluded from the Distomus-Halichondria association by some factor connected with the slope of the rock surface, other than inadequate illumination.

6. Freedom from silt deposition may be responsible for many of the peculiarities of the Distomus-Halichondria association,—in particular for the importance of sponges, cœlenterates, and tunicates.

7. Barnacles play an important part in the recolonisation of bare rock surfaces.

While studying some of the ciliates found in the region of the Marine Biological Laboratory at Plymouth, England, from January to May, 1929, the author collected from Chelson Meadow a hypotrich which undergoes binary fission only during encystment. This interesting behaviour, which appears to be rare among the Hypotrichida, led to a study of the morphology of the free-swimming form; preliminary to further investigations, including a study of both protective and reproductive cysts.

The formation of nitrate in the water of an aquarium tank stocked with fish was followed. As much as 1 gram per litre expressed as sodium nitrate was found.

By adding lactate or tartrate to the water the development of denitrifying bacteria brought about almost complete removal of the nitrates and nitrites in the water.

The experiments form part of an investigation made under the direction of Dr. Jan Smit.

1. Measurements of the penetration of light of various colours into the sea were carried out by means of a selenium rectifier cell. The mean vertical absorption coefficients were: for blue, 0·177; green, 0·153; “white,” viz. no filter, 0·216; yellow, 0·243; red, 0·345. The results accord well with those obtained under similar conditions with emission cells and show that, for water a couple of miles offshore, green light penetrates best.

2. The current was measured using the potentiometer-telephone method as for emission cells, but determining the drop in potential across a low resistance, 10,100, or 1000 ohms. The motion of the ship was too violent to permit of the use of any available galvanometer of adequate sensitivity.

3. Rectifier cells are more convenient to use than emission cells, as the currents to be measured are much larger and the absence, of high potentials greatly simplifies all insulation problems. On the other hand the curvature of the illumination–current relation involves additional labour in standardizing and in calculating results.

Since 1921 hydrographic data have been collected by the S.S. Salpa and several merchant vessels, the records being published in the Rapport Atlantique and the Bulletin Hydrographique each year. A description of the conditions in the mouth of the Channel—the varying temperature, salinity, and movements of the water masses—during the years 1925–1928 was published in this Journal, Vol. XVI., pp. 791–820, and included a review of the objects of these investigations and the methods used in working up the collected data. This present publication forms a continuation of this. The same methods of dealing with the data have been used.

In the English Channel in summer a small difference in specific alkalinity between the surface and bottom waters has been established by a statistical method. This is not due to re-solution of bottom deposits of calcium carbonate with which the water is supersaturated. It is attributed to removal of calcium from the surface waters by plankton and an attempt has been made to calculate the production of calcareous plankton.

Phosphorus in plankton has been determined by digestion with sulphuric acid and perhydrol followed by colorimetric determination.

Nitrogen has been readily determined by the micro-Kjeldahl method of Parnas and Wagner.