bluuebunny/crossref_metadata_2025_split huggingface dataset:
Histology of the light organs of Pholas dactylus (Lamellibranchia)
Authors: Nicol J. A. C. 
Published: May 2009

The piddock, Pholas dactylus L., gives off a luminous secretion when irritated. The luminous glands which produce the secretion are two longitudinal stripes in the exhalant siphon, a pair of triangular organs in the mantle cavity near the base of the siphon, and a stripe around the ventral rim of the mantle (Panceri, 1872).The histology of the light-organs has been described several times. A light-organ is covered by a simple columnar ciliated epithelium, below which are many glandular cells, which discharge through the surface epithelium. The outer part of the glandular layer consists of a mass of large mucus cells. Deeper lies a second glandular region containing large cells with long necks that extend to the external epithelial surface. Dubois (1892, 1914, 1928) believed that the photogenic tissue was made up of two kinds of secretory cells; these were the superficial ciliated cells, which possessed glandular bases (fixed secretory cells); and deeper lying glandular cells derived from clasmatocytes (migratory secretory cells). Rawitz (1891) clearly distinguished a mucous from an underlying photogenic layer. The latter, according to Förster (1914), contains pyriform cells with long necks. He believed that he could distinguish a secretory cycle in the photogenic cells. Exhausted cells at the beginning of the cycle possessed an alveolar cytoplasm; granules began to appear in the cytoplasm; the granules increased in number and stained intensely with iron haematoxylin. Those photogenic cells which were filled with granules were in the active secretory state. Transitional stages between the inactive (or depleted) cells and the active (granular) cells were rare.
The fecundity of English Channel plaice
Authors: Bagenal T. B. 
Published: May 2009

This paper is the fourth in a series dealing with the fecundity of flatfish (Bagenal 1957 a,b, 1958), and is concerned with the egg numbers in ripening female plaicePleuronectes platessa L. caught in the English Channel.On 27 November 1957, eighty-five plaice with maturing ovaries were caught in Rye Bay, Sussex; on I December, eight similar fish were caught in Lyme Bay, and duringDecember sixty-four locally caught female plaice were brought in to the Plymouth Laboratory. The dates of the collections were chosen because in January 1957 I had found that a small proportion of the Plymouth plaice were spent. All the fish caught in November and December were at a suitable stage for fecundity estimation: that is, the eggs were well developed though none had begun to turn translucent.
An Interesting Young Velella in the Plymouth Plankton
Authors: Lebour Marie V. 
Published: May 2009

On 2 February 1943, after some very fierce south-westerly storms, a curious object was found in the inshore plankton which proved to be the ‘float’ of a very young Velella in the Rataria stage. In order to be certain of its identity some small complete Velellas were compared. These were kindly sent by Miss Delap of Valencia, to whom I am much indebted. They ranged from 1.5 to 2 mm. across and were very similar to the young forms described and figured by Huxley (1858), who identified them with the Rataria of Eschscholz (1829). In this stage the float is growing and may already have the crest, a soft, much higher structure, projecting above it. In order to see the float clearly one of the Irish specimens, 2 mm. across, was macerated in 10% caustic potash, the float separating out and proving to be exactly similar to the Plymouth specimen.The peculiar structure of this float and the fact that the available figures of the Rataria of similar size show only the external features make a short note desirable, for in the existing figures one cannot be certain of the exact extent and position of the float. So difficult was it to decipher that, although it seemed very probable that we had the float of a Velella, it was not possible at first to be certain.
On the Fertility of Marine Cladocera with a Note on the Formation of the Resting Egg in Evadne Nordmanni Loven and Podon Intermedius Lilljeborg
Authors: Cheng C. 
Published: May 2009

A statistical study was made of the fertility of Evadne nordmanni, Podon intermedius, P. leuckarti and P. polyphemoides in the Clyde Sea-Area and of the former two species off Plymouth. The mean fertility of parthenogenetic females varies with different species. This is not correlated with the size of the species.Within the species, Evadne nordmanni and Podon intermedius, there exists, in general, a positive correlation between the size and the fertility of parthenogenetic females.The fertility of Evadne nordmanni is subject to seasonal variation. This is not correlated with fluctuations in the abundance of diatoms.An inverse relationship was observed in Evadne nordmanni between the reproductive capacity of parthenogenetic females and the intensity of sexual reproduction.A brief account was given of the formation of the resting egg in Evadne nordmanni and Podon intermedius.
The Life History of Patina Pellucida (L.)
Authors: Graham Alastair , Fretter Vera 
Published: May 2009

Patina pellucida occurs in two facies with characteristics of habitat and structure, the latter' affecting mainly the shell. One variety, pellucida, which lives on the fronds of Laminaria, has a smooth, elpngated oval and low shell, which is transparent and brown in colour, with 2-8 blue rays radiating backwards from the summit which is placed at the anterior end; it is normally devoid of either epiphytic or epizoic growth. The soft parts are pigmented because of the translucency of the shell, the radular teeth only slightly worn, and the arrangement of the gut coils adapted to a long, narrow haemocoelic space. The second variety, laevis, lives in caves in the holdfasts of Laminaria, and has a rough, round and usually high shell, though the proportions are more variable than in the variety pellucida. The shell is opaque and brown in colour, with 2-46 blue rays and also red-brown ones more or less regularly alternating with them; it has a central summit and is frequently covered with growths of various sorts. The soft parts are not pigmented, the radular teeth are considerably worn, and the coiling of the gut modified to fit into the rounder haemocoel.The life history may be summarized: the animals breed maximally in winter and spring, the planktonic larvae settling mainly in May as spat about 2 mm. in length. They grow so as to reach a length of about 5 mm. in the following autumn and 10 mm. after a year of sedentary life, becoming sexually mature at 5 mm. length. The majority of the animals die after a settled life of 12 months, but a few linger on into a second year: nearly all these belong to the variety laevis, living a sheltered life within the holdfast of the weed, not exposed like pellucida to the effects of wave action and storm.
The Pelagic Phase in the Life History of the Amphipod Genus Bathyporeia
Authors: Watkin E. Emrys 
Published: May 2009

The zonation of four species of the genus Bathyporeia, from high-water mark to low-water mark, in Kames Bay, Millport is given. B. pilosa occurs above the high-water mark of neap tides, B. pelagica is a mid-tidal form and B. elegans a low-water form. The latter, together with B. guilliamsoniana, extend beyond low-water mark. Of the population, as it occurs in the sand, 15 % are adult males, 26 % adult females, giving a proportion of adult to
immature forms of 4 1 : 59.The analysis of forty-five tow-net samples taken across the bay at night shows that the same zonation of the species is maintained; the proportion of adults to immature forms in these samples, however, is as 57: 43, and of the 57 % of adults, 42 % are adult males, 15 % adult females.When the samples are related to the day of the lunar month it is shown that the numbers increase in the tidal waters in the periods immediately preceding the full moon and preceding and partly overlapping the new moon. A nocturnal vertical movement appears to be a marked feature of a few benthic amphipdd families, but the factors which cause this migration are problematical and require much further investigation.
The Physiology of Maturation and Fertilization inPomatoceros Triqueter(L.) I. The Nature of the Material
Authors: Cragg J. B. 
Published: May 2009

The description of the material used in the present investigation does not conform with that of Horstadius. Attention is drawn to this lack of agreement. A hypothesis based on viscosity changes within the egg has been advanced to explain the rounding off of eggs in sea water.By means of what is called the transfer series the egg batch has been divided into a number of parts; the last liberated eggs being the ripest. The occurrence of large numbers of egg batches giving low maturity values has been attributed to maturity resulting from a series of changes whose rate after initiation gradually increases.Attention is drawn to seasonal changes in the reactions of the germinal products. No definite lunar periodicity is shown in the ripening of the eggs.
The Biology ofChthamalus Stellatus(Poli)
Authors: Moore Hilary B. , Kitching J. A. 
Published: May 2009

Chthamalus stellatus is a littoral barnacle very similar in habitat and general ecological relations to another littoral barnacle, Balanus balanoides. In those localities where both species flourish they compete considerably for space, and also possibly for food. The fact that B. balanoides settles sooner after the winter storms than does Chthamalus probably favours the former.Chthamalus is characteristically a southern species and Balanus balanoides a northern one, but the north and south ranges of the two species overlap in the British Isles and in France. The determining factor is presumably temperature.Chthamalus is an Atlantic species, and Balanus balanoides is more characteristically a North Sea species. The essential factor in Atlantic water remains unknown, although in respect of a need for Atlantic water Chthamalus resembles Sagitta elegans and intertidalEchinus esculent.
Observations on Flounders Pleuronectes Flesus L. Marked in the Esturaries of the Tamar and Lynher
Authors: Hartley P. H. T. 
Published: May 2009

1039 flounders were marked with numbered vulcanite disks in the estuaries of the Tamar and Lynher.148 flounders were recaptured and of these seven fish were recovered a second time after one recovery and release, and one fish was recaptured on three occasions after two previous recoveries and releases.Only two fish were recovered at a distance from Plymouth. Both had moved eastward, up the English Channel.There was little or no growth in the winter months.Individual growth rates were found to vary greatly.The flounders living in the last reach of the Tamar near Saltash tended to remain in one limited area during the winter months, save for a drift down-stream of some of the larger fish. In the spring there was an upstream movement of the smaller, immature fish.Flounders which had gone down to the sea to spawn might return to the river in which they were marked, or to the other river of the two which join to form the Hamoaze, or they might move right away from the area where they were marked.
The Portuguese Man-of-War, Physalia Physalis L., in British and Adjacent Seas
Authors: Wilson Douglas P. 
Published: May 2009

The occurrence in the summer of 1945 of a swarm of Physalia physalis L. off the south-west coast of the British Isles has initiated a survey into records of its appearance on the Atlantic coasts of Europe during the past 100 years. Unpublished records for 1912, 1913, 1934 and 1935 were discovered and are listed with those already known. The 1945 strandings are considered in detail in conjunction with meteorological data for the period involved. It is concluded that winds, rather than water movements, are the main factor in transporting the swarms towards the British Isles and it is considered likely that the swarms come from the Azores-mid-Atlantic region rather than from the Canaries-Gibraltar district.Associated with the Physalia were Lepas fascicularis and L. pectinata, some Velella, a few turtles (Caretta caretta), and possibly an Opah fish (Lampris luna), all of them, with some reservation respecting the last-named, surface organisms that would come under the same meteorological influences as the Physalia.A living specimen of Physalia gave an opportunity to observe the method of feeding of which few previous first-hand accounts exist. The capture of the prey by the dactylozooids and its subsequent digestion by the gastrozooids is illustrated by photographs from life and is described in some detail. It is suggested that the rolling of the pneumatophore from side to side, dipping the crest in the water, is a calm-weather habit directed to keeping moist the upper surface exposed to the air.
On the Biology and Relationships of the LamellibranchXylophaga Dorsalis(Turton)
Authors: Purchon R. Denison 
Published: May 2009

The exhalant siphon ofXylophagais greatly reduced and its opening is situated within the burrow. Faeces accumulate in the posterior end of the burrow in a compact mass.The ctenidia and labial palps ofTeredo, BankiaandXylophagaare modified and reduced, unlike those of the Pholadidae. The ctenidia are flat and homorhabdic and possess no ciliary sorting mechanisms; they consist of the outer demibranch only.The ctenidia ofXylophagaare composed of a direct lamella; those ofTeredoandBankiaare divided into anterior and posterior portions connected by a branchial groove which is an extension of the marginal food groove of the gill. The number of filaments in the anterior portion of the gill varies according to the species, and is of assistance in identification.The labial palps ofTeredo norvegicaare least reduced; inXylophaga dorsaltsreduction is greater, though selection of food material is still exercised. The greatest reduction has occurred inTeredo megotaraand inT. navaliswhere there is no selection.The ciliated mantle tracts inTeredoand inXylophagaplay an important part in limiting the quantity of food particles passed from the ctenidia to the mouth.
The Biology and Trematode Parasites of the GastropodLittorina Neritoides(L.) on the Plymouth Breakwater
Authors: Lysaght Averil M. 
Published: May 2009

An account is given of the distribution, life history and trematode parasites ofLittorina neritoideson the Plymouth Breakwater; a few observations from other localities are included.The smaller snails are most abundant on the exposed southern slopes of the Breakwater. Many of the larger ones live more or less permanently in water in small cylindrical pits on the top of the Breakwater. This habitat is apparently very similar to that described by Fischer-Piette (1932) as occupied permanently by this species at Cap Martin; Lebour (1935) has sometimes found it in water in other places in the Plymouth area.The conditions necessary for metamorphosis of the larvae, the need of the adults for shelter from the force of the waves, and the requirements for spawning appear to be of more importance in determining the choice of habitat than the negatively geotactic and varying phototactic responses found in this species by Fränkel (1927).The breeding season lasts from September to April. The males are ripe about two months before most of the females. Experimental evidence is given which makes it most improbable that there is any downward migration for spawning. From the examination of plankton samples it appears that there is a fortnightly spawning rhythm coincident with high tides, and that even the snails living in water discharge their eggs only at these periods.The distribution of the size groups is discussed. The proportion of males decreases significantly in the larger size groups and it is probable that there is a difference in the growth-rate of the sexes.
Observations on the Night Tidal Migrant Crustacea of Kames Bay
Authors: Watkin E. Emrys 
Published: May 2009

The faunal analysis of forty-eight samples taken with a coarse tow-net across the intertidal waters of Kames Bay during 1936 shows that the night migrant crustacean population falls into two well-marked groups: (a) those species which live in the intertidal sand and perform simple vertical migrations at night-time into the intertidal waters, and (b) those which are carried in by the tide into the intertidal area from various habitats which lie beyond the low-water mark of spring tides. In the former group the species of the genera Bathyporeia and Pontocrates are dominant and they retain their zonation as migrants, the population consisting of individuals in all stages of maturity. This is in sharp contrast to the latter group, typified by Gammarus locusta and Idotea viridis, which occur over the whole tidal range with a population in which the young immature stages are dominant. The Haustoriids Urothoë brevicornis and Haustorius arenarius occur as inhabitants of the sand, the former appearing occasionally in the tow-net samples and the latter absent from them. The Cirolanid Eurydice pulchra performs both day and night migration for the purposes of feeding.Discussion of the results indicates the lines along which further investigations may be carried out.
The Occurrence and Breeding of Sagitta Elegans Verrill and Sagitta Setosa J. Müller in Parts of the Irish Sea
Authors: Pierce E. Lowe 
Published: May 2009

An investigation has been made of the species of Sagitta present in parts of the Irish Sea, their relative occurrence, and the annual number of reproductive cycles of each species. Three stages of maturity as described by Russell (1932a) have been used. To determine the maturity the Sagitta were transferred to a solution of 75% alcohol and stained with borax carmine.S. elegans Verrill and S. setosa J. Müller were collected in Liverpool Bay and in Port Erin harbour, Isle of Man. The former species was predominant at Port Erin. The coasts of Liverpool Bay have been added to the permanent range of S. setosa.At Port Erin there appears to be but one chief spawning period for S. elegans which extends generally from January through May. Following May the young forms appear in numbers and gradually mature through December to repeat the annual cycle.There appear to be two main breeding seasons for S. setosa in the outer Mersey Channels. The first and most noticeable begins in April and extends into June. There is evidence for a second breeding period in August.Both species were found in the samples taken from Morecambe Bay and Anglesey. The stage of maturity of these agreed with the Sagitta caught at the same time at Port Erin and Liverpool.The total monthly catches of Sagitta from Port Erin and the outer Mersey Channels have been recorded.
The Larval Stages of Portumnus (Crustacea Brachyura) with Notes On Some Other Genera
Authors: Lebour Marie V. 
Published: May 2009

Two species of Portumnus occur in the Plymouth area, P. biguttatus (Risso) and P. latipes (Pennant). P. biguttatus was the only species recorded when the old fauna list of Plymouth was published (1904), but since then it is known that P. latipes is very common in certain sandy areas (see Plymouth Marine Fauna, 1931), far commoner than P. biguttatus.P. biguttatus is rare and has not been seen since 1906. It was first found by W. Garstang and R. Todd on Drake's Island in Plymouth Sound, burrowing in fine gravel (1905), and two specimens, and are recorded from a sandy patch from the north-east corner of Drake's Island. A female in berry was recorded from the same locality by R. Todd, and L. R. Crawshay dredged one in Cawsand Bay in 1906. Apparently the eggs were not hatched out and the zoea of this species is unknown. In August 1902 R. Gurney obtained a megalopa in the plankton and from it secured the first crab stage. He describes the megalopa as being intensely blue. The cast skin of the megalopa and the crab obtained from it (Fig. 3a-c), which he kindly handed to me, are described in my paper of 1928 (Lebour, 1928c, p. 518, pl. viii, figs. 1–3). There is no reason to doubt the accuracy of the determination, especially because, as shown below, corresponding stages of P. latipes as well as the zoeae are now known and are very distinct, differing considerably from those of P. biguttatus.
Structure and Function of the Gut inSpadella CephalopteraandSagitta Setosa
Authors: Parry D. A. 
Published: May 2009

Spadella cephaloptera1. The oesophageal epithelium is composed of granular and vacuolated cells. The former produce a glutinous secretion which appears to immobilize and lubricate the prey. The function of the vacuolated cells remains undetermined.2. The intestinal epithelium is composed of gland cells and absorptive cells. The gland cells contain large vacuoles which disrupt when food is taken, restitution taking several hours. The absorptive cells accumulate large concretions of fat and other material as digestion proceeds; later this gradually disappears.3. The absorptive cells in the intestine are ciliated. The cilia may be concerned with respiration and excretion; there is no evidence that they are concerned with osmoregulation.4. The rectum has a ciliated columnar epithelium.5. The general course of feeding and digestion,is discussed.6. It is stated in a footnote that the reproductive system ofSpadellais similar to that ofSagitta.Sagitta setosa7. The oesophagus is divided histologically as follows: (i) a region of granular cells round the mouth; (ii) a region of vacuolated cells; (iii) a region of compound granular cells; (iv) a second region of granular cells. The granular cells produce a profuse secretion with probably the same function as the glutinous secretion inSpadella.8. The intestinal epithelium is composed of compound granular cells and simple columnar cells. By comparison with the intestine ofSpadellathe former are regarded as enzyme-secreting cells and the latter as absorptive.
Methods of Surveying Laminaria Beds
Authors: Chapman V. J. 
Published: May 2009

Previous methods of survey by American workers are described and the differences between the species of seaweed involved are emphasized. The small stature of the European kelps renders all methods of survey difficult and the results can only be described as the best approximations. The British survey was divided into (1) a preliminary survey in order to determine the regions with the biggest beds, and (2) a detailed survey, when some of these major beds were mapped in detail. The primary survey was a rapid affair and the results were based on information obtained from (a) use of boat and grapnel, (b) existence of cast weed, (c) lobster fishermen, (d) coastguards, fishery officers, borough surveyors, harbour-masters, (e) inspection from cliffs, (f) a study of Admiralty Charts.In the section on the detailed survey the different types of grapnel employed and also the method of using the box sextant are described. The use of an echo-sounder to locate weed beds is discussed and the different types of record obtained over various types of bottom or weed are noted. The use of a viewbox and personal observation is also mentioned, and finally an account is given of aerial photography as a means of survey. The most suitable conditions for success are noted and also the technique of interpretation for both oblique and vertical photographs. The plotting of these two types of photograph is described in some detail.