In 1866 Hincks described the hydroid Cuspidella humilis: later, in his History of the British Hydroid Zoophytes (1868, p. 210), he added two further species to the genus, C. grandis and C. costata. At that time the reproduction of Cuspidella was not known.

Metschnikoff (1886, p. 83 and Taf. V, Fig. 1) described the development of the eggs of Laodicea cruciata and reared them to the hydroid stage. These had sessile hydranths and elongated polyps with ten slender tentacles, long and short alternating. Metschnikoff remarked on their similarity to Cuspidella.

The possibility that certain plankton organisms retained by a stramin net may prove of value as indicators in elucidating the water movements at the mouth of the English Channel is shown.

The water populated by Sagitta setosa is shown to be clearly demarked from that in which S. elegans lives, the latter living to the west of the Channel mouth south of Ireland. The water in which S. elegans lives has here been called “western” water.

It is shown that the planktonic indicators for “western” water are Sagitta elegans, Sagitta serratodentata, Aglantha rosea, Stephanomia bijuga, Clione limacina, Meganyctiphanes norvegica, Thysanoessa inermis, and Cosmetira pilosella (in spring and summer only). Sagitta setosa is regarded as an indicator of “Channel” water. Muggiæa, Salps, Doliolids, Liriope exigua and Euchœa hebes are regarded as indicators of “south-western” water.

The geographical distribution of S. setosa is discussed. It is shown that it is probably a neritic species mainly confined to the English Channel and North Sea.

S. setosa predominates off Plymouth when the easterly element in the Dover Straits current is suppressed and the flow of Atlantic water into the North Sea from the north is strong (Carruthers' Theory). The two Sagitta populations swing to and fro off Plymouth so that, with a strong flow of Atlantic water into the North Sea from the north, the S. elegans population is pushed westward to the mouth of the Channel and S. setosa occurs off Plymouth.

During the course of the five years, 1930 to 1934, an agreement has been found between the occurrence or absence of concentrations of the diatom Rhizosolenia styliformis in the southern North Sea and the variations in the composition of the Sagitta population off Plymouth In the years in which Ehizosolenia, an indicator of Atlantic water, was abundant in the southern North Sea S. setosa predominated off Plymouth; when Rhizosolenia was absent S. elegans predominated.

These diatom concentrations have been shown by Savage and Hardy t o have an apparent influence on the movements of the Herring which is reflected in the landings at Yarmouth and Lowestoft.

1. It has been shown that the stomach of the plaice can digest proteins by an extra-cellular enzyme—apparently pepsin. Fats and carbohydrates appear to be unattacked in the stomach.

2. In the intestine, proteins are further attacked and the mucous membrane contains a trypsin and an erepsin.

3. The liver and the wall of the gall-bladder are more potent sources of trypsin than is the intestine; the former contains, also, a cathepsin, and the latter an erepsin. It is not certain whether any of these enzymes can be secreted into the intestine; administration of pilocarpine failed to make the bile definitely active in digesting proteins, but it is possible that there may be some other route by which the secretion may reach the intestine.

4. Fats and carbohydrates are digested in the intestine, since the mucous membrane of the intestine—and also the wall of the gall-bladder and the liver—contain lipase and amylase. The liver is a far more potent source of lipase than is either the gall-bladder or the intestine, but this lipase may be partly intra-cellular in action.

5. The hydrogen-ion concentration of the contents of the stomach and intestine has been shown to be consistent with the extra-cellular action of the enzymes found in the respective mucous membranes. The mucous membrane of the stomach is capable of secreting acid, and that of the intestine is capable of bringing about its neutralisation.

In November, 1933, a few medusæ were found in the plankton off Plymouth belonging to the genus Eucheilota. The only species of this genus so far recorded from northern European waters is Eucheilota maculata Hartlaub. The medusæ differed in several respects from this species, one constant difference being that the marginal vesicles never contained more than one concretion. In this respect they resembled E. duodecimalis A. Agassiz, but differed in having a much greater number of tentacles and marginal vesicles.

In October, 1934, the medusæ appeared again in considerable numbers and it was now possible to establish the constant features of the species which has apparently never been described before, except possibly for a drawing given by Hartlaub without a description (see below).

Records are given on the abundance of the pelagic young of teleostean fishes off Plymouth as shown by half-hour oblique hauls with the 2-metre stramin ring-trawl.

In comparison with similar observations made since 1924 the year 1935 has been the poorest yet recorded.

A parallel between the quantity of phosphate in the water at the beginning of the year and the abundance of young fish is further confirmed. In January, 1935, the winter maximum phosphate value was the lowest yet recorded.

Myrianida pinnigera (Montagu) is one of the representative Syllids in the Plymouth district. Here, it is found always in close association with Ascidiella aspersa and Phallusia mammillata, possibly feeding upon the body fluid of these Ascidians.

1. The general structure of the statocyst and the combined sensory setae in Honiarus vulgaris have been described.

2. The statoliths consist of sand grains attached to the setæ by a hyaline secretion.

3. Numerous tegumental glands occur in the sub-epithelial tissues. Though not situated beneath the setæ, their distribution varies in accordance with that of the setae. Their ducts have characteristic funnel-shaped endings, opening into the cavity of the statocyst.

4. The hyaline secretion agrees in all its reactions with the cuticle, never with the chitin.

5. The conclusion is reached that the hyaline secretion is formed by these tegumental glands and that this constitutes an important accessory function of these glands.

Although workers in several European countries (England, Germany, Russia, Scotland) are stated (5) to be carrying out marking experiments on rays or skates, the writer is not aware of any recently published account of the results of any of these researches. Fulton (4, p. 191), however, records that in the years round about 1890 he marked 71 thornback rays (R. clavata) and 23 specimens of grey skate (R. batis) in Scottish waters. Two of the thornbacks and one skate were subsequently recovered. Of the former, one—about 36·5 cm. in width on marking—remained at liberty for about three months before being recaptured and had travelled about 13 miles from the place where it had been set free. The other—35 cm. in width—remained at liberty for 278 days and travelled about six miles. The single skate, recaptured after only 10 days, had in that time changed its position by 10 miles. No records of size increments are given.

This paper embodies various observations which were made from time to time while the author was a member of the staff of the Plymouth Laboratory. It also outlines certain generalisations based on the author’s previous published work and that of other recent workers in the field of comparative physiology of feeding and digestion.

BashfordDean in his Monograph on the Chimaeroid Fishes (1906), describing the North Pacific species Chimaera colliei, states that it is omnivorous and that the “broken shells of mollusks are commonly found, as well as fragments of good sized crustaceans, as indeed the scanty literature records.” He further states that “in the gut of C. monstrosa Faber finds crustacean and shell-fish fragments; Monticelli, quoting Lütken, Cyprina islandica;hellips; Olsson finds also (and his observations are the most detailed hitherto published on the feeding of Chimaera) chætopods, amphipods, echinoids and polyps.”

The following is an account of the gut contents of several specimens of Chimaera monstrosa which the authors were fortunate enough to obtain recently.

The specimens which were taken from the Atlantic Ocean sixty miles N.W. of Black Eock (Lat. 54° N., Long. 12° W.) at a depth of 220 to 250 fathoms, were preserved in dilute formalin.

The actual examination of the gut contents was carried out as follows.

The œsophagus and rectum were ligatured, and that part of the gut lying between the two ligatures was removed and placed in a dish of dilute formalin. The gut was then opened by a longitudinal incision, and its contents carefully transferred to the dish where they were subsequently examined by means of a binocular microscope. The food fragments were then provisionally classified, care being taken not to separate such parts as may have belonged to the same organism during life.

The following piece of research has been undertaken at the suggestion of the Conway Fisheries Eesearch Station of the Ministry of Agriculture and Fisheries.

For some years experiments have been in progress at Conway in connection with oyster breeding. During the oyster season, from May to August, when the tanks of the Kesearch Station are not being used for mussel cleansing, cultural work on the oyster (Ostrea edulis) has been carried out. One of the greatest difficulties is the feeding of the larvae in the free swimming state and this problem affects both tank culture and culture on a smaller scale. In some years a settlement of spat has taken place, but it is not known what conditions made that phenomenon possible. It has been suggested that the available food supply might be of importance, since both detritus on the one hand, and seaweed spores and gametes on the other, have been regarded as constituting the food of larvae (Martin, 1923). As nothing over 10μ can be ingested by the larvae, there is a limit to the spores and gametes which may be used.

In May, 1933, during routine gonad examinations, a hermaphrodite specimen of Echinocardium cordatum was observed. It was collected in the sandy beach of Port Erin Bay at low water of ordinary spring tides, and was 4.7 cm. in length, which corresponds, in a normal specimen, to an age of about four years. The external colour was dark, although not more so than in other specimens in the batch, but the gonad was exceptionally pigmented—almost black. In this locality the colour of the test and gonad becomes progressively darker with increasing age, and affords some measure of the latter.

The specimen was examined within half an hour of being collected, and portions of the gonad were fixed within ten minutes of being opened, so that fertilization and segmentation could not have advanced in the laboratory to the stage found. Smears from the gonad showed ova, of which about 50% were ripe, together with ripe spermatozoa. The gonoduct contained ripe ova, together with segmenting ova and early embryos. Figure 1 is a photograph of the contents of the gonoduct, taken immediately after opening, and showing ova with a four-cell stage and a blastula. Cultures were set up in sterile sea-water, from the contents of the gonoduct, and also from the gonad itself, as well as a control fertilization from normal urchins, and from all of these normal early plutei were reared. Those cultures from the hermaphrodite specimen did not, however, develop much further, possibly owing to premature fertilization in the abnormal conditions in the gonad.

It has been shown (1, 2) that the capacity for building up visual conditioned responses is common to many types of fish when the unconditioned stimulus used as the basis for the “conditioning” is food. Preliminary work at Plymouth, using the fish Blennius gattorugine, showed that was possible that a knowledge of wave-length discrimination in that species might be acquired by the now familiar method of “conditioning” to an electric shock. This work was continued when I came to Cullercoats, and six specimens were used which were sent from Plymouth in 1929. All of these died within a short space of time during the succeeding winter months, owing to the intense cold. It was therefore necessary to restrict the investigation to Blennius pholis L., which is both plentiful and hardy at Cullercoats. Some progress had already been made and in Part II (2) it was intimated that an analysis would be made of the capacity for wavelength discrimination in Blennius pholis using an electric shock as the unconditioned stimulus. The present paper gives the results of that enquiry as far as it was taken.

Normal behaviour traits control the ability of fishes to form conditioned motor responses. This is shown by a series of experiments upon various species of fish in which it is found that Pleuronectids are found incapable of forming such responses for at least 200 associated presentations whilst other fishes have done so in less than 40. The bearing of the results on current theories of animal learning is briefly discussed.

1. Echinus esculentus was studied from four localities in the Isle of Man and from one in the Clyde.

2. The inshore races are thicker shelled and natter, and on all grounds the urchins become taller with increasing age.

3. Size distribution measurements on the Chickens material showed a rapid growing period in the spring, followed by cessation of growth for the rest of the year. There is a correlation between amount of growth in a given year, and the sea temperature. On the Breakwater the males and females grow at slightly different times of year.

4. Concentric pigmented rings are demonstrated in the test, and are shown to be annual. They are used for estimating the growth rates on the different grounds, which are compared.

5. The duration of life is four to eight years, and perhaps more in the very large southern urchins.

This cercaria was found to be very common in specimens of Littorina rudis (Maton) and L. obtusata (Linné) collected at Aberystwyth during February and March, 1935, occurring in twenty out of fifty specimens of L. rudis and in four out of forty specimens of L. obtusata. It was, on the other hand, very rare in L. littorea, only two infested individuals being found out of a total of two thousand molluscs examined. In all three species of mollusc the parts of the digestive gland most heavily infested appeared white or creamy-white in colour.

The form described here appears to be almost identical with Cercaria ubiquitoides recorded by Stunkard (1932) from L. littorea and L. rudis occurring on the coast of Brittany. Certain differences are found between my specimens and those of Stunkard. It is difficult to determine whether these differences are individual or specific because there are so few larval characters in cercariæ of the Ubiquita group which can be used for separating species. The problem is rendered more difficult by the close resemblance of the adult trematodes (species of the genus Spelotrema).

While collecting in Menai Straits in July, 1932, Professor Orton found three specimens of an Edwardsia-like anemone. They were kept alive in finger bowls for several months; and when they were examined in the following November about two dozen young anemones were discovered with them. These Professor Orton kindly showed to me, and suggested a further examination of th young and adults.

Sea water contains very little zinc. Values from 0–73 mg. per cubic metre have been cited in Physics of the Earth, V, 180, Washington, 1932. According to Orton it is less than 0–1 parts per million in the English Channel. Dieulafait found 2 nig. and Bodansky 7–3, erroneously quoted as 73 above. The method described here permits of the detection of as little as 8 mg. per m3 using 200 ml. of distilled water in a Hehner tube, the delicacy of the reaction being much greater than that of any other for zinc. Sea water from the English Channel gives no turbidity and so is unlikely to contain as much as 8 mg. per m3. The method is brought forward on account of its usefulness in detecting and estimating zinc in sea water contaminated by contact with metallic surfaces. Its use in fresh water has already been described (Analyst, 1935, 60, p. 400, No. 711, June), and to this paper reference may be made for some possible sources of interference and for the origin of the reagent.

In tow-nettings from Plymouth Sound, June 20th, 1935, Acartia clausi were abundant and inside these copepods, emerging from them and free in the water were very large numbers of larval trematodes, easily identified as Hemiurus communis. This is not a new record, for this parasite has already been described from the same Copepod in Plymouth waters in May and February (Lebour, 1923), but it has always been rare. In no case have more than two parasitised specimens been seen from these regions, and no seasonal appearance has been noticed. Much has been written about these trematodes which grow in the bodies of copepods until they are of such a large size that they inevitably kill the host and just before it dies emerge from between the joints, if not eaten before this with the copepod, but I think this is the first time that they have been recorded in any quantity at one time. Since my first communication Steuer (1928) has written about the geographical distribution of these hemiurids parasitising copepods and is of the opinion that all those in Northern seas belong to Hemiurus lühei and H. communis. In the Mediterranean the hemiurids known have not yet been found in copepods but usually in Sagitta, or are found living freely in the sea and these probably belong to H. rugosus which lives in the adult state in the pilchard.

1. Frequent treatment with cutch is injurious, but Olie's method (cutch and ammoniacal copper sulphate) applied every four months preserved cotton netting for six years and eight months in Aquarium sea-water.

2. Varieties of cutch tested showed differences which were quite insignificant in comparison with the improvement effected by adopting One's method, which was effective with all on cotton.

3. A single treatment by Olie's method preserved trawl twines of Benares sann hemp, New Zealand Phormium fibre and of sisal (E. African) for 34, 34 and more than 48 months respectively under conditions such that the untreated twines perished in less than five months.

4. Cotton treated with cutch alone is but little improved by a dip in crude phenols, but a neutral tar oil obtained from the “Coalite” low temperature distillation process was found useful.