bluuebunny/crossref_metadata_2025 huggingface dataset:
Some Experiments on the Function of the Pericardial Organs in Crustacea
Authors: Alexandrowicz J. S. , Carlisle D. B.
Published: May 2009

Experiments with isolated hearts of various Crustacea (Cancer pagurus,Maia squinado,Homarus vulgaris,Squilla mantis) were performed in order to test the postulated secretory function of the pericardial organs (nerve trunks of unusual structure lying in the pericardial cavity). Tests were made with extracts of these elements added to the fluid perfusing isolated hearts.

InCancer,HomarusandSquillathe extracts caused a distinct increase in amplitude and frequency of the heart beat, and their effect proved to be very similar to that produced by adrenaline and noradrenaline tested on the same hearts. InMaiathe extracts produced an increase in amplitude and decrease in frequency of the heart beat.

Extracts of the pericardial organs ofCancer pagurusgave the fluorescence reaction characteristic of adrenaline and related compounds. Blood taken from the pericardial cavity gave the same reaction, but that taken from the leg arteries did not.

It is assumed that the function of the pericardial organs in the Crustacea consists in liberating, through fine neuropile-like terminations of the nerve fibres, some hormone passing with the blood into the heart and producing on it a stimulating effect. There is certain evidence that the pericardial organs might release a second hormone having an inhibitory and perhaps also a stabilizing effect on the heart rhythm.
A New Dredge for Collecting Burrowing Animals
Authors: Forster G. R.
Published: May 2009

The 'anchor-dredge' is a lightly built one-sided instrument designed to catch deep-burrowing animals. The depth to which it digs is dependent on the pull of the warp and not on the weight of the dredge.

From a trawler, it is best to work the dredge from the forward gallows, and give it a 'tug' as the ship is moving astern.

Comparative tests and direct underwater observations have shown that the anchor-dredge samples the in-fauna more efficiently than do either large rectangular and oval dredges, or the conical dredge.

A description and plan is given of a larger model, designed for use from a 6o-ft. or 90-ft. ship.
The Respiration of some Planktonic copepods II. The Effect Of Temperature
Authors: Gauld D. T. , Raymont J. E. G.
Published: May 2009

The respiratory rates of three species of planktonic copepods, Acartia clausi, Centropages hamatus and Temora longicornis, were measured at four different temperatures.

The relationship between respiratory rate and temperature was found to be similar to that previously found for Calanus, although the slope of the curves differed in the different species.

The observations on Centropages at 13 and 170 C. can be divided into two groups and it is suggested that the differences are due to the use of copepods from two different generations.

The relationship between the respiratory rates and lengths of Acartia and Centropages agreed very well with that previously found for other species. That for Temora was rather different: the difference is probably due to the distinct difference in the shape of the body of Temora from those of the other species.

The application of these measurements to estimates of the food requirements of the copepods is discussed.
Note on the Absorption of Organic Phosphorus Compounds by NitzschiaClosterium in the Dark
Authors: Harvey H. W.
Published: May 2009

It has been observed by Chu (1946) that the marine diatom Nitzschia closterium, in bacteria-free culture, grows in the light with inositol hexaphosphate as phosphorus source, and with glycerophosphate.
The Seasonal Variation in the Copper Content of Sea Water
Authors: Atkins W. R. G.
Published: May 2009

In previous papers (1932, 1933) the author showed that sea water taken from the English Channel contained about 10 mg./m.3 of copper, and obtained agreement between electro-deposition with subsequent colorimetric analysis and colorimetric analysis carried out on sea water concentrated to one-fifth of its volume. For extraction of the copper complex, carbon tetrachloride was found to be the most convenient solvent. The changes throughout the year have, however, only recently been determined. It is of interest to see that water from Station E1, surface, taken 23 March 1931, gave 10 mg./m.3 by direct colorimetry and 9·7 with electro-deposition, whereas the extraction method curves for 1948 and 1949, read off for the same date, showed respectively 9·4 and 11·4 mg./m.3.
The Preservation of Fishing Nets, Trawl Twines and Fibre Ropes for Use in Sea Water
Authors: Atkins W. R. G. , Warren F. J.
Published: May 2009

A trade waterproofing of sisal rope had still some effect after 3 days in sea water, the untreated being four-fifths saturated in 1 hr.

Treating manila, sisal and coir rope with Cuprinol or tar increases the wet weight at the most only slightly as less water is taken up than without preservative.

Water equilibrium is not attained till long after the B.S.I, specification test period for waterproofing sisal rope, but some effect of waterproofing may be distinguished up to perhaps 3 days.

On cotton netting copper naphthenate preservatives were most durable in a clean sea-water basin, but Dr Olie's method with cutch and ammoniacal copper sulphate ran them close and is cheaper. The best lasted 9 months as against untreated 5½ months.

On trawl twines the British Columbia grade of Cuprinol, a proprietary mixture containing copper naphthenate, was the best of those tried, and the twines lasted 16 months as against almost 9 for untreated manila.

On thin sisal rope six copper preparations are still under test.
Spontaneous Squirting of an Ascidian,Phalliusia MammillataCuvier
Authors: Graham Hoyle
Published: May 2009

The previous work on spontaneous activity in ascidians is briefly reviewed: there is clear evidence for the existence of spontaneous contractions of the siphons of certain monascidians but no function has been ascribed to this activity.Phallnsia mammillataexhibits spontaneous contractions of its siphons at intervals of 6-9 min. over long periods in Plymouth tank sea water. The siphon contractions are synchronous. The frequency of the contractions may shift fairly quickly under constant conditions to a higher or lower rate which is usually twice or one half the normal rate.

A method of recording the volume of water propelled by spontaneous activity is described. The method also records the ciliary through-current at the same time as the squirts.

The frequency of the squirting is increased during a period of partial or complete starvation. It is reduced again by adding food cultures to the water.

The physiological mechanisms involved in the spontaneous activity are investigated and comparisons are made with the spontaneous activity exhibited byMetridium senileandArenicola marina. It is finally suggested that the spontaneous squirting of certain ascidians is an integral part of their feeding mechanism.
Nervous Organs in the Pericardial Cavity of the Decapod Crustacea
Authors: Alexandrowicz J. S.
Published: May 2009

In the pericardial cavity of the decapod Crustacea the nerve fibres end in characteristic neuropile-like networks which surround bundles of thicker fibres or spread over the pericardium wall and the heart ligaments. It is proposed to designate the whole system of these elements as 'pericardial organs'.

The arrangement of the elements constituting the pericardial organs varies in different groups of the Decapoda. In the Brachyura the bundles of fibres surrounded by neuropiles form conspicuous trunks linked with each other; the main parts of these trunks are situated at the openings of the branchiocardiac veins into the pericardial cavity. In Eupagurus bernhardus two main trunks flank the heart giving off branches which spread in various directions and form at some places plexuses on the pericardium wall. In Leander serratus the pericardial organs are represented by several trunks running near the lateral wall of the pericardium in the dorsal direction and uniting by archshaped branches. In Homarus vulgaris there are four comparatively much shorter trunks situated at the lateral wall of the pericardial cavity, but plexuses of neuropile-like nerve fibres spread over large areas.

The trunks of the pericardial organs are suspended in the pericardial cavity in such a position that they may be bathed on all sides by the blood passing from the gills. The plexuses extending over the membranes are situated in places also exposed to the blood stream. There is evidence indicating that the pericardial organs produce substances influencing the heart-rhythm. It is assumed that these substances are liberated into the blood by a process of neurosecretion occurring at the terminations of the nerves.
The Seasonal Cycle in the Cornish Pilchard, Sardina Pilchardus Walbaum
Authors: Hickling C. F.
Published: May 2009

1. In the pilchard (Sardtha pilchardus Walbaum) of Cornwall there is a substantial seasonal variation in the mean weight of a fish of given length. The weight is highest in late autumn and early winter, and least at the end of winter and the early spring.

2. These changes in weight are largely due to variations in the fat content of the fish, which are richest in fat at the beginning of the winter fast, and poorest at the end of it. But, especially among the larger fish, the 'residue', chiefly proteins, are drawn upon at the time of the exhaustion of the fat, and consequently at the time of minimum mean weight. The water and ash content show no seasonal variation, and therefore play no part in the observed seasonal variation in the mean weight of the entire fish.

3. The gonads have their lowest mean weight in August, increase in weight slowly throughout the winter, and are at their maximum state of development from April to July. The spawning season, as deduced from these samples, is from March to September.

4. The rate of feeding is greatest in the same months as the spawning months, namely, from April to July. From July to September the average weight of food per stomach decreases, probably not because the planktonic food is then less abundant, but because it is shared among a greater number offish. In October there is a rally in the rate of feeding, but from November to February or March is a period of fasting, when very little food is taken.

5. The food of the pilchard is exclusively planktonic. In the spring, and again in the autumn, diatoms are abundant or even dominant in the food; in the summer, copepods and Crustacea are the chief items of food.
Vertebral Variation in Teleostean Fishes
Authors: Ford E.
Published: May 2009

Since the publication of Heincke's classic treatise on the herring the counting of vertebrae has become a standard operation in the biometric analysis of samples of teleostean fishes taken at random from local populations. But while such routine counting has undoubtedly added greatly to our knowledge of the incidence and magnitude of vertebral variation in a number of economically important species, it has occasioned no little confliction of opinion as to the significance of this variation. Difficulties arising out of my own work on the herring at Plymouth have led me to make a general study of the teleostean backbone in as many species as possible, in an endeavour to learn more of the nature, extent and cause of vertebral variation. After examining over one hundred species, mostly from local waters, I have come to the conclusion that the subject presents a great and varied field of research which is at present but little explored. It would be idle to suggest, therefore, that the present paper should be considered as anything more than an introductory survey of the many problems awaiting detailed investigation. Even so, it may serve to indicate the scope and present position of the Plymouth studies, and prepare the way for fuller work in the future, both at Plymouth and elsewhere.

I have received the greatest assistance from Mr L. S. Wisdom, Laboratory Attendant at the Plymouth Laboratory, whose skill in preparing skeletons for study, and keen interest in all matters relating to the research, I most gratefully acknowledge.
The Newly Hatched Larva of Spirontocaris Spinus (Sowerby) Var. Lilljeborgi Danielssen
Authors: Lebour Marie V.
Published: May 2009

On February 29 1937 the larvae of Spirontocaris spinus var. lilljeborgi were hatched out in the Dove Marine Laboratory by Dr H. O. Bull and sent to me for examination. As the larvae differ in certain important points from those of other species known and there is no published account of them, it seems worth while giving a short description, although the later larvae have not been identified and it was not possible to rear them further.
Oxidation-Reduction Potential in Sea Water
Authors: Cooper L. H. N.
Published: May 2009

The activity of oxygen in sea water and standard oxygen electrode potentials at a range of temperatures have been computed.

Accurate values for the thermodynamic ionic product of water, Kw, found by Harned & Hamer, have been applied to the calculation of the activity of hydroxyl ion in sea water from pH measurements.

The activity of water in sea water has been computed from the lowering of the freezing-point.

From these data the theoretical reversible oxidation-reduction potential of sea water has been calculated.

.Typical data for the irreversible potential in the pH range 1-8 have been derived from Hoar's results with which experimental determinations made by Dr Atkins agree. Thus the oxidation-reduction potential of sea water is controlled solely by the oxygen system.
The Preservation of Contractile Marine Animals in an Expanded Condition
Authors: Gohar H. A. F.
Published: May 2009

The importance of killing contractile animals in an expanded condition cannot be over-estimated. A glance at the immense confusion and uncertainty which prevails in several branches of tropical marine invertebrates, and in particular the Coelenterata, will give a clear picture of the value of good preservation. Killing contractile animals in an expanded condition has always offered considerable difficulty. Several methods have been recommended for different animals, but it is often very difficult to choose the appropriate one, since animals belonging to one and the same group may behave quite differently towards any method. The writer, during his work for the last three years at the Marine Biological Station of the University of Cairo at Ghardaqa in the Red Sea, has taken great pains to preserve a variety of marine invertebrates as fully expanded as possible. Some of the successful results and the methods used are therefore given here.

The commonest method for the present purpose is the use of narcotics. The most familiar of these are menthol, chloral hydrate, alcohol, magnesium sulphate and cocaine. Owing to the difficulty in obtaining cocaine it cannot be freely used for general purposes. Menthol enjoys a great reputation for narcotization which, in fact, it does not quite deserve. Although in some few cases it gave good results, yet in the majority it was quite unsatisfactory, as delicate animals begin to macerate before they are properly narcotized. It is generally applied in the crystal form and sprinkled on die surface of the water. Apparently its low solubility is responsible for a great many of its failures.
The Structure and Function of the Tube Feet in Certain Echinoderms
Authors: Smith J. E.
Published: May 2009

Comparison of the methods of adhesion and locomotion of the typical members of the four classes of the Eleutherozoa reveals a similarity of the adhesive mechanism in the Asteroidea, Echinoidea and Holothuroidea in that adhesion is due in part to suction and in part to the secretion of mucus. The ophiuroid, on the other hand, has tube feet which, because of their lack of a well-defined sucker, must adhere merely by their intrinsic stickiness. The ability to make use of suction results from the possession of a sucker so fashioned that the median part of the disk may be withdrawn from the surface of contact, with the resultant production of a vacuum. The sucker of the asteroid, echinoid or holothurian tube foot is well adapted for this purpose. An essential feature of such a disk is the presence of an arborescent system of connective tissue fibres extending from the basal plate to the outer limit of the ectoderm. By means of this system, the pull initiated by contraction of the longitudinal musculature of the podium is transmitted to the ectoderm of the sucking disk, the central part of which is thereby lifted up. Where suction plays no part in adhesion, as in the Ophiuroidea, the arborescent system of fibres is lacking.
The Size of Diatoms II. Further Observations on Rhizosolenia styliformis (Brightwell)
Authors: Wimpenny R. S.
Published: May 2009

1. Diameter measurements of Rhizosolenia styliformis from the Antarctic, the subtropical Atlantic and Pacific Oceans and from the North Sea and neighbouring waters have made it appear necessary to set up two varieties, oceanica and semispina, in addition to the type of the species R. styliformis. The type as I describe it has been called var. longispina by Hustedt, but elsewhere it has often been figured as the var. oceanica of this paper. Var. semispina is synonymous with the form represented by Karsten as R. semispina Hensen. It differs from R. semispina as drawn by Hensen and its synonym R. hebetata forma semispina Gran, but is thought likely to be linked by intermediates. If this is so R. hebetata may have to be extended to include and suppress R. styliformis, as var. semispina is linked to the type by intermediates. Var. oceanica has no intermediate forms and, if R. hebetata is to be extended, this variety should be established as a separate species.

2. Var. oceanica is absent from the southern North Sea and appears to be an indicator species related to oceanic inflow.

3. Auxospore formation was observed for the type in the southern North Sea in 1935 and biometric observations suggest that a period of 3-4 years elapsed between the production of auxospore generations in that area. Outside the southern North Sea for the type, measurements give no indication of auxospore generations occurring at intervals exceeding a year. While auxospore formation has been seen in var. oceanica from the Shetlands area samples of June 1935 and July 1938, this phenomenon has not been observed for var. semispina.
A Comparison of the Feeding Mechanisms of Calma Glaucoides and Nebaliopsis Typica
Authors: Rowett H. G. Q.
Published: May 2009

The feeding mechanism of the nudibranch Calma glaucoides (Alder & Hancock) has been described by Evans (1922) and that of the crustacean Nebaliopsis typica (Sars) by Cannon (1931) and myself (1943). Calma is seasonally relatively abundant in the coastal waters of parts of Europe where it is found attached to the eggs of certain fishes. It is known to feed exclusively on these eggs and young embryos. Nebaliopsis is a deep pelagic form from the Antarctic Ocean. It has been obtained only rarely and cannot be observed alive and in its natural environment. Two specimens were available for examination. Thus complete certainty about the diet is impossible. The external features and mouth parts were described by Cannon and the structure of these suggested that Nebaliopsis, like other known Nebaliacea, might be a filter feeder. Examination of the morphology of the gut and its contents indicates that this is very improbable. There is no mechanism for the sorting out of particles of different sizes such as is found in other filter feeders. The food passes into a blind sac and there is no apparent means by which the large quantities of indigestible material taken in when particles are filtered from the water indiscriminately might be evacuated. In addition to this negative evidence the food mass found in the large storage chamber of one specimen was completely homogeneous and structureless, its appearance in section suggesting coagulated yolk. It has therefore been suggested that Nebaliopsis feeds on fish eggs found floating in the deeper water layers.
On the Habits and Adaptations ofAloidis (Corbula) Gibba
Authors: Yonge C. M.
Published: May 2009

1.Aloidis (Corbula) gibbais a eulamellibranch specialized for life in muddy gravel substrata to depths of up to about 80 fathoms.

2. The shell is asymmetrical, the margin of the smaller, left valve being uncalcified and so fitting within the marginal region of the right valve. A possible manner in which this asymmetry is produced by the differential secretory activities of the two mantle edges is discussed.

3. The marginal periostracum of the left valve has strengthening calcined regions posteriorly, probably to protect the siphons when extruded.

4. The external ligament is reduced and the resilium condensed, possibly permitting some antero-posterior rocking of the shell valves when the adductors contract.

5. The process of burrowing is described; on its completion the animal is anchored by a single byssus thread.

6. The siphons are very short, the tentacles of the siphonal sheath lying on the surface of the substratum. The inhalant siphon is wide and relatively insensitive; it draws in much bottom material. The exhalant siphon is tubular and very sensitive. It is controlled by two paired bands of muscle.

7. The great quantities of pseudo-faeces which accumulate are expelled by periodical contractions of the 'quick' portions of the adductor muscles, the asymmetry of the shell valves causing great reduction in the size of the inhalant chamber. The foot may also assist in clearing the chamber. 8. The large ctenidia create a very powerful current; they are adapted for dealing with large amounts of sediment by means of specialized terminal, guarding and cirrus-like cilia. Control of 'pumping' is primarily by means of the exhalant siphon.

9. The stomach is large in correlation with the great amounts of inorganic material carried in with the food.
The Life History of Kellia Suborbicularis
Authors: Lebour Marie V.
Published: May 2009

Kellia suborbicularis (Montagu) has long been known to be viviparous. Lovén (1848) mentions this fact and Jeffreys (1863, p. 227) quotes Mr Clark who “found in the ovary of one individual ova in an advanced state with fully formed testaceous fry.” It is probable, however, that these shelled larvae were in reality contained in the gill pouch where later workers have found them. Pelseneer (1935, p. 517) says that the eggs are incubated in the internal gill lamella, and this was also observed by myself.

It is striking that although the shelled larva is extremely small when liberated (shell 0.064–0.08 mm. in length), the late planktonic larva is very large (shell 0.30–0.37 mm. in length) and one of the most conspicuous bivalve veligers in the plankton. This indicates a prolonged free-swimming life quite unlike that of the oyster, Ostraea edulis, whose shelled larvae are liberated only to lose the velum in a few days. These late larvae of Kellia have been kept in bowls and plunger jars in the Plymouth Laboratory until they metamorphosed and for months afterwards, growing into beautifully clear and transparent individuals which undoubtedly belonged to this species.

Kellia suborbicularis is placed by Winckworth (1932) in the Erycinidae, but this family is closely related to the Leptonidae, Montacutidae and Galeommatidae, most or all of whose members are viviparous. Lovén (1848) described the young shelled stage of Montacuta ferruginosa and M. bidentata, the latter species now being referred by Winckworth toMysella. Both keep their young in the gill pouch until the shelled stage and Lovén's beautiful figures show that the early shelled stage in each of them is very like that of Kellia.
Evolution of Ciliary Feeding in the Prosobranchia, with an Account of Feeding in Capulus Ungaricus
Authors: Yonge C. M.
Published: May 2009

1. Ciliary currents concerned with rejection of sediment from the mantle cavity of pectinibranch Prosobranchia consist of A, currents carrying heavier particles to the inhalent opening; B, currents carrying medium particles across the floor of the mantle cavity; C, currents carrying fine particles over and between the gill filaments for later consolidation by the mucus from the hypobranchial gland. Material in currents B and C is rejected from the exhalent opening.

2. The feeding currents in ciliary feeding Prosobranchia represent modifications of these rejection currents.

3. In Vermetus novae-hollandiae currents B and C only are modified, material being passed to the mouth region, where it is mixed with mucus from the large pedal gland, by way of a food groove.

4. In Crepidula fornicata and other Calyptraeidae all currents are modified for feeding and there is an endostyle for mucus secretion.
The Fate of the Larval Organs in the Metamorphosis of Ostrea Edulis
Authors: Cole H.A
Published: May 2009

This is the first part of a study of the metamorphosis of the larva of the European flat oyster (Ostrea edulis) and deals with the fate of the larval velum, foot, adductor muscles and eyespots.

The apical area of the larval velum forms the basis of the upper labial palps of the spat.

The bulk of the velar tissue is broken up and cast off or eaten; the total dissolution of the velum being complete within 48 hr. of attachment.

The larval foot after effecting attachment rapidly shrinks in size and disappears within 72 hr. of attachment. Partial loss of its tissues probably occurs.

The statocysts persist in the spat.

Following fixation the anterior adductor muscle rapidly degenerates.

The so-called pigment spots of the larval oyster have the structure of eyes. During metamorphosis they degenerate rapidly in situ..
On Two Species of the Trematode Genus Didymozoon from the Mackerel
Authors: Baylis H. A.
Published: May 2009

Taschenberg (1879) briefly described, under the name of Didymozoon scombri, a trematode which he recorded as occurring in pairs in cysts on the inside of the gill-covers of Scomber colias at Naples. Odhner (1907) found what he believed to be the same species not uncommonly in small specimens of S. scombrus off the west coast of Sweden, but was unable to find it in the larger fish taken in the early summer. He gives a minute description and excellent figures of the worm. Johnstone (1914) has also given a good, though diagrammatic, figure of its anatomy. Odhner describes the worm as occurring most commonly in paired cysts on the upper pharyngeal bones, but also in exceptional cases in cysts on the inside of the gill-covers and on the outside of the head, close behind the eye. About half the cysts examined by him contained two worms, the rest from three to seven. Johnstone describes the cysts as being most commonly situated ” “on the roof of the mouth beneath the pharyngo-branchials”, but also sometimes on the basi-branchials, on the external surfaces of other parts of the gill-bars, or on the internal surface of the operculum. One cyst contained as many as sixteen worms. According to Dollfus (1926), he and Monod found cysts containing one, two, three or more worms in the mucosa of the mouth, palate and gills of S. scombrus, and also single unencysted worms under the transparent skin behind the eye.

Thus at least two authors record the same worm as occuring both inside the mouth and on th e outside of the head, behind the eye.
Edgar Johnson Allen (1866–1942)
Authors: G. P. B
Published: May 2009

The late Dr E. J. Allen was the son of the Rev. Richard Allen, a Wesleyan minister and as such liable to change the sphere of his work every few years. For this reason E. J. Allen passed his childhood in Cornwall, went to school in Exeter, and lived during his late boyhood in the Worth Valley, going into Leeds to attend the Yorkshire College (now University of Leeds); his education was continued by the University of Berlin, an interval of teaching in Antigua, and University College, London, followed by a Royal Society research studentship at the Plymouth Laboratory. Excepting Antigua, every one of these epochs claimed in him its own loyalties: a few years ago he seriously considered going west to Cornwall to end his life where he first remembered it; he much admired Franz Eilhard Schulze, who taught him at Berlin, and W. F. R. Weldon, his Professor of Zoology at University College, yet kept a lively gratitude for what he had learned from Professor Miall at Leeds.

To this very varying environment during the first third of his life we may attribute through the next half-century much of his universal power of sympathy and contact with all sorts and conditions of men. Unselfish by nature, he had the example of a singularly wide-minded father; then bred as a boy in Cornwall, Devon, and West Riding, as a man among London University students and Berlin University students, with the West Indian interlude— there was no class or nation who could not feel an understanding with Allen.
Studies in the Functional Morphology and Embryology of Onchidella Celtica (Forbes and Hanley) and their Bearing on its Relationships
Authors: Fretter Vera
Published: May 2009

Onchidella celtica lives in communities in intertidal rock crevices, emerging only when uncovered by the tide during the milder months (March- November). It feeds on young algae and diatoms, rasping them from the rock with the radula which is lubricated by a mucous saliva. The distensible crop and stomach afford ample storage space for the food. The stomach consists of three chambers (Fig. 2), and the dorsal (d) and ventral (v) chitinous plates of the posterior one, the gizzard, crush the contents and help to direct the soluble portion towards the ducts of the digestive gland. There are three of these the two anterior (Id, rd) are large and lead from the initial chamber of the stomach (ic), the third (pd) is small and joins the posterior wall of the gizzard (pzv). The digestive gland secretes into the stomach; no cellulase occurs. Feeding experiments suggest that the digestive cells of the gland absorb only fluid. Lime and excretory cells occur in the crypts of the digestive epithelium, the latter concerned with taking up excretory matter from the blood and elaborating it into spherical masses for evacuation with the faeces
The Larvae of the Genus Porcellana (Crustacea Decapoda) and Related Forms
Authors: Lebour Marie V.
Published: May 2009

Although the larva of Porcellana is one of the earliest known decapod larvae and at a later date the different stages of P. longicornis were well described by Sars (1889), there is yet much that is unknown. Few larvae have been actually hatched from the egg and in no case has the number of larval stages been definitely ascertained. In order to fill in some of the gaps in our knowledge a detailed study of the two common Plymouth species was begun (P. longicornis and P. platycheles). Unfortunately, war conditions made it difficult to obtain material and many specimens were lost as the result of air-raids; it was therefore not until the summer of 1942 that the work could be finished.

It is now possible to distinguish between the two species in all stages. Both have been hatched from the egg, larvae from the plankton have moulted and the post-larvae have been obtained from the last larvae. A comparison with Gurney's (1938a) notes on the species from the Red Sea and his general comments on the larvae of the genus and its relatives (1942) is of much use. These, with the first larvae of Petrolisthes armatus hatched by myself at Bermuda and certain larvae described by other workers, have made it possible to make some progress in the elucidation of the relationships of the larvae.

Porcellana longicornis and P. platycheles are both common at Plymouth; but whereas the latter is confined to coastal waters and lives between tidemarks and down to about 3 fathoms, the former has a much wider range and although occurring withP. platycheles between tidemarks extends to well beyond the Eddystone grounds.
Measurement of Phytoplankton Population by the Pigment Extraction Method
Authors: Gardiner A. C.
Published: May 2009

1. In order that the Harvey method shall estimate without avoidable error the concentration of marine or freshwater phytoplankton, it is essential, firstly
Corella halli n.sp., a new ascidian from the English Channel
Authors: Kott Patricia
Published: May 2009

In September 1950 Dr H. W. Parker of the British Museum (Natural History) kindly sent me a specimen of an ascidian collected by the yacht, Manihine, for identification. This has proved to belong to an unnamed species of the genus Corella, here described as C. halli. The unique type specimen was obtained from dredgings on a shingle bottom at 35 fathoms, 10 miles WSW. of the Casquets in the English Channel, 30 August 1950 (Manihine, Station no. 81).

External features. The animal (Fig. IA) is enclosed in a transparent test, laterally flattened, circular, of 4 mm. diameter and fixed basally to pieces of sand; there is no stalk. The branchial aperture is terminal anteriorly; the atrial aperture is also anterior and dorsal to the branchial aperture. Both apertures are sessile.
The breeding of Crepidula fornicata (L.) in the River Blackwater, Essex
Authors: Chipperfield P. N. J.
Published: May 2009

The chain-forming prosobranchiate gastropod Crepidula fornicata is not indigenous to British waters, but has been introduced during the last 70 or 80 years, probably from North America, upon imported oysters, and, during this period, has spread to most of the oyster beds on the south-east and south coasts of this country (see Orton, 1950b, for a recent discussion of its present distribution). In spite of the interest shown in this species because of its detrimental effect upon oyster culture, and because of its well-known change of sex from male to female, little is known in the literature of its breeding habits here, or in North America. Conklin (1897) states that the spawning period in New England lasts from early summer to about mid-August, no larvae being found in late August. Murie (1911), in discussing the introduction of this species, elaborates upon Conklin's observations, and gives evidence that females, in samples of Crepidula taken from the River Colne in May and September 1898, contained spawn beneath their shells. Orton (1912a, p. 438) states that he is ‘informed by Professor Conklin that American Crepidulae begin to spawn in May and possibly in April, whilst English Crepidulae begin to spawn in early March’. In a footnote, he adds ‘Crepidula spawned in tanks at Plymouth in early February’.
Studies in the biology of Talitridae (Crustacea, Amphipoda): visual orientation in Talitrus saltator
Authors: Williamson D. I.
Published: May 2009

The nocturnal migrations of Talitrus over the sand surface cover considerable distances, frequently taking specimens well below mid-tide level. In spite of this, by day the species occupies burrows in a broad, but fairly well-defined, zone in the region of high-water mark. The nocturnal distribution of the animals can be attributed to a somewhat random search for food, but the question arises (worded anthropomorphically), how do the animals find their way back to the high-water region? Perhaps in an attempt to answer this question, Verwey (1929) states briefly that Talitrus orientates on the beach by mnemotaxis to the wind, sun and direction of the sea, and by menotaxis (compass reaction). Mnemotaxis, or orientation by memory images, has been entirely eliminated from the modern classification of orientation reactions (Fraenkel & Gunn, 1940), so that Verwey's contribution is reduced to a statement without evidence that Talitrus orientates by means of a compass reaction to an unknown stimulus, and no other author mentions the orientation of Talitrus on the beach.
On the variability of replicate plankton samples and some applications of ‘contagious’ series to the statistical distribution of catches over restricted periods
Authors: Barnes H. , Marshall S. M.
Published: May 2009

The variability to be expected in replicate plankton hauls, using several methods of hauling and a number of different nets, has been examined by Winsor & Clarke (1940). Some of the variability is due to true sampling variations, inevitable when discrete entities in suspension are sampled, and some is due to inadequacies of sampling technique. Winsor & Walford (1936) found that the variability of their vertical net hauls could be explained on the basis of a random distribution of the population, the variations being ascribed to variations in the volume of water filtered in successive hauls. They fully realized that the alternative, namely a non-random distribution of the population, was not disproved; but they considered that since widely different organisms showed little difference in variability the evidence was strongly in favour of a random distribution. They did note, however, that agreement between these different organisms was less marked when the numbers caught were large.
An apparatus for the collection of plankton in the immediate vicinity of the sea-bottom
Authors: Bossanyi J.
Published: May 2009

In connexion with a study of plankton-benthos interrelationships off the coast of Northumberland, an apparatus was designed for the collection of plankton in the immediate vicinity of the sea-bottom, a layer usually missed by ordinary plankton sampling gear. The present account is a brief description of this apparatus, together with some notes on its handling at sea and the work carried out with it on board the Dove Marine Laboratory's boat, the Pandalus II.

I was fortunate in having the willing co-operation of numerous people who helped in various ways, and to whom I am very greatly indebted. These included my father, Mr E. Bossanyi; Mr T. E. F. Sanderson of Eastcote, Middlesex; Prof. A. C. Hardy, Oxford University; Dr C. E. Lucas, Fishery Laboratory, Aberdeen; Prof. A. D. Hobson, Director of the Dove Marine Laboratory; Dr H. O. Bull, Assistant Director; Messrs Ellis and Co., Engineering Works, Swalwell, County Durham; the Department of Mechanical Engineering of King's College, Newcastle upon Tyne; and the entire scientific, boat and technical staff as well as research students at the Dove Marine Laboratory. Without them, the design, construction and employment of the apparatus would not have been possible.
The seasonal abundance of young fish XI The year 1949
Authors: Corbin P. G.
Published: May 2009

The 1949 production of young fish and plankton in Plymouth off-shore waters continued to remain at the low level characteristic of the last few years. Collections were made by half-hour oblique hauls of the 2 m. stramin ring-trawl; the dates are given in Table I. The fortnightly averages of all young fish, excluding clupeids, are shown in Table II with comparative figures for 1948 and for the period 1930–34. The highest value, in the second half of June, may have been unduly weighted, since only one collection was made in the fortnight. The monthly total catches of young fish are given in Table III. The sum of the monthly averages for all young fish (459) was slightly higher than the 1948 value (3111), due to larger catches of clupeids; young fish other than clupeids continued to decrease. A few post-larval herring were present in January, and for the third successive year young Mugil spp. occurred; two in October and one in December. No young plaice were caught, although a very small number of plaice eggs were present in January and February. Plankton, other than young fish, was very sparse throughout the year, Calanus being even scarcer than in 1948. Sagitta setosa was the dominant Sagitta species, although never abundant, and as in recent years the numbers were particularly low from February to June. A few S. elegans occurred in November and December (maximum, 66 specimens). The abundance and percentages of the Sagitta species are shown in Fig. 1.
The biology of the common prawn,Leander serratusPennant
Authors: Forster G. R.
Published: May 2009

This work was undertaken at the suggestion of Mr F. S. Russell that little was known about the natural history of even so familiar a species asLeander serratus, the common prawn of the English Channel, which may at times form a valuable natural resource to the inshore fishermen. Attention was therefore chiefly concentrated on its growth rate and breeding biology. In spite of the long breeding season the statistical method of studying growth was adopted when preliminary results appeared successful. By this method additional data could be obtained on distribution and migration. In the closely related genusCrangon, growth has been shown to be retarded under laboratory conditions (Nouvel & van Rysselberge, 1937), so that an experimental study could not be relied on to give a picture of the normal life history. Höglund's recent monograph (1943) has treatedLeander squillain great detail. However, this species differs considerably in size and distribution fromL. serratus, and it was felt that a similar study in the Plymouth area would not be mere repetition; in fact the biology ofL. squillaitself differs somewhat in the two districts.
Observations on Nephrops norvegicus (L.) and on an epizoic population of Balanus crenatus Brug
Authors: Barnes H. , Bagenal T. B.
Published: May 2009

The Dublin Prawn or Norway Lobster, Nephrops norvegicus (L.), is widely distributed on soft muddy bottoms, usually between 10 and 50 fathoms. It is found as far north as Iceland and the North Cape, is common in the North Sea and off the Atlantic shores of the British Isles, and extends as far south as the coast of Morocco; a variety, v. meridionalis (Zariquiey-Cenarro, 1935) is found in the Mediterranean and Adriatic (see Havinga, 1929, and Heldt & Heldt, 1931, for details of its distribution). Some aspects of the general biology of Nephrops have been dealt with by Höglund (1942) and Poulsen (1946) for Scandinavian waters, and by McIntosh (1904, 1908) and Storrow (1912)for the waters off north-east England. To a large extent all these workers relied on market catches.
Studies on Chaetopterus variopedatus (Renier). I. The light-producing glands
Authors: Colin Nicol J. A.
Published: May 2009

Chaetopterus variopedatus (Renier) is a tube-dwelling worm that has note worthy luminescent powers. Production of light is by an extracellular process resulting from the discharge of a luminescent slime into the sea water. Because of its luminescent ability, the epidermal glands of Chaetopterus have been repeatedly described in detail, but it is still not clear what elements produce the luminescent secretion. I have, therefore, re-examined the histology of the light-producing regions of Chaetopterus with a view to determining the character of the photocytes or light-producing glandular cells.
On the biology of Calanus finmarchicus. VII. Factors affecting egg production
Authors: Marshall S. M. , Orr A. P.
Published: May 2009

Comparatively little is known about the factors affecting egg-laying in Calanus. Deductions from work in the field have been made by Nicholls (1933a, b) and Marshall, Nicholls & Orr (1934), and experimental work in the laboratory has been done by Raymont & Gross (1942).

Emgg-LayingInCalanus

The anatomy of the reproductive system has been described in detail by Lowe (1935). In the female there is a pair of diverticula extending from the proximal end of the oviduct into the head region, and into this the developing eggs pass. Each diverticulum has a dorsal and a ventral channel, and the eggs pass from the dorsal into the ventral channel and then into the oviduct proper. The oviduct rises from the forward end of the ovary and crosses the body laterally and ventrally so that a short part of it can be clearly seen.
The biology of Asterias rubens L. III. Carotenoid pigments in the integument
Authors: Vevers H. G.
Published: May 2009

In the Plymouth area there is often a marked and consistent difference in coloration of starfishes (Asterias rubens) from different populations. Starfish from populations to the south of Plymouth Breakwater are red-brown or occasionally pale yellow-brown in colour, whereas those from a population living well within Plymouth Sound have been found to be consistently bright red or brick red in colour (Vevers, 1949). In the present work analysis has been made of the integumentary carotenoids of dark red-brown A. rubens taken from the trawling grounds between Plymouth Breakwater and the Eddystone.
Trace elements in the common brown algae and in sea water
Authors: Black W. A. P. , Mitchell R. L.
Published: May 2009

Sea water probably contains all the chemical elements, although a number of them have not yet been detected. Considerable information is available on the occurrence of various elements in marine plants and animals, but it is far from complete for any one biological group. Except for recent work by Spooner (1949), on the absorption of radioactive strontium and yttrium by marine algae, no detailed study of the trace elements in the brown algae, nor any attempt to correlate the trace elements in sea water with those in the algae, appears to have been carried out. The following is a brief résumé of the work that has been done in this field.
The responses and orientation of the bivalveLasaea rubraMontagu
Authors: Morton J. E.
Published: May 2009

Lasaea rubra, like other small Erycinacea, is unusual among eulamellibranchs in its relatively great mobility on the surface of the substrate. It can crawl about as freely as a small gastropod and lays down a mucous trail for the attachment of its progressing foot, drawing the shell and body rhythmically forward after each advance thrust of the foot. Unlike some other Erycinacea,L. rubrahas no well-defined sole; it attaches by the sharp lower edge and part of the side of the foot, which is strongly ciliated and well supplied with mucous glands. In most burrowing eulamellibranchs, the site of communication with the surrounding water has shifted to the paired siphons at the posterior end. The Erycinacea, however, have an anterior inhalant siphon; and—as in forward moving prosobranch gastropods (Morton, 1958)—there is an obvious adaptive advantage in receiving the ingoing current from the water into which the animal is moving.
A note on Dallina septigera (Lovén), (Brachiopoda, Dallinidae)
Authors: Atkins D.
Published: May 2009

The discovery of a homoeomorph, Fallax dalliniformis, of Dallina septigera (Lovén) dredged with that species (Atkins, 1960) and, it is believed, sometimes confused with it, certainly by Fischer & Oehlert (1891), has made a brief redescription desirable. During the present work more than a hundred D. septigera of shell length 5–31 mm have been obtained, and most of them examined internally.

The original description in Latin—without figures—of Dallina septigera (= Terebratula septigera) was by Lovén in 1846 (p. 183). Unfortunately his description does not now clearly separate his species from Fallax dalliniformis, except perhaps his failure to mention the presence of dental plates, pedicle collar and spiculation. It is doubtful how much weight can be attached to this, for on the same page he failed to mention the presence of dental plates in Macandrevia cranium. He gave the length as 28 mm, width as 21.5 mm and depth as 17 mm.
Defensive acid-secretion in marine gastropods
Authors: Thompson T. E.
Published: May 2009

An important function of the gastropod shell is to protect the body against attack by predators. If the shell of a whelk is broken away and the soft animal is then offered to a hungry cod, it is eaten readily. Many successful gastropods, however, lack an external shell as adults (although it is certain that all have evolved from shelled ancestors) and might be expected to be eaten by fish as readily as is the naked body of a broken whelk. The purpose of this paper is to describe part of an investigation into whether this is in fact true.