bluuebunny/crossref_metadata_2025_split huggingface dataset:
The relationship of the mantle and shell of the Polyplacophora in comparison with that of other Mollusca
Authors: Beedham G. E. , Trueman E. R. 
Published: August 2009

The structure and growth of the polyplacophoran shell, characteristically consisting of eight plates surrounded by a girdle, is examined in the light of current views on the relationships of mantle and shell in the Bivalvia. The periostracum and outer and inner calcareous layers of the shell of the latter group are homologous with the cuticle, tegmentum and articulamentum respectively of the shell of the Polyplacophora. The margin of the mantle consists of a large marginal fold, which secretes the cuticular girdle, and a small accessory fold bearing mucous cells. These are functionally comparable with all three folds of the mantle margin found in other molluscs, although anatomically the marginal fold of the chitons probably represents only the inner surface of the outer fold of the mantle margin.The cuticle not only forms the girdle, which bears calcified spines or spicules, but also extends between the shell plates. The principal part of the cuticle consists largely of mucopolysaccharide material but there is also a thin discrete inner region which is similar chemically to the periostracum of other molluscs. The cuticle, possibly without spines, probably covered the entire dorsal surface of a primitive placophoran and beneath this, plates developed. As these grew the cuticle became worn away except marginally and between the plates. It is suggested that a covering of mucus over the visceropallium may have been the forerunner of the molluscan shell and the possibleevolutionary relationships of the shell throughout the Mollusca are discussed.
The systematics of the genus Lates (Teleosti: Centropomidae) in Lake Albert, East Africa
Authors: Holden M. J. 
Published: August 2009

The systematics of thc genus Lares Cuvier, 1828 in Lake Albert were examined. It is concluded that the inshore form, originally described as Lates albertianus Worthington, 1929 and subsequently as L. niloticus albertianus should be considered as a synonym of L. niloticus (Linné, 1762) but that the offshore form, Lates macrophthalmus Worthington, 1929,warrants full systematic status. It had been relegated to subspecific status, L. niloticus macrophthalmus.The lectotype for L. macrophthalmus is selected and redescribed. A method by which the species could have evolved, based on suspected differences in partial pressures of oxygen at whichthe blood haemoglobins of the two species become saturated, and on desiccation of the lake in the Pleistocene period, is described.The diagnostic value of allometry in distinguishing between the two species on a morphologicalbasis is discussed, as is the distribution of the two species in Lake Albert.The possible significance of interspecific differences in the shape of the caudal peduncle andcaudal fin is considered.
Associations of Rotifera in the zooplankton of the lake sources of the White Nile
Authors: Green J. 
Published: August 2009

Plankton samples for rotifers were collected by means of vertical hauls with phytoplankton nets at eight stations on Lake Albert during the course of a year. Similar hauls were taken from Lakes Kyoga, Victoria, George and Edward in October and November. The rotifers found in the samples are listed and some estimates of their abundance and seasonal occurrence in Lake Albert are given. The most important planktonic rotifers are Keratella tropica and several species of Brachionus. Other species may also become locally or temporarily abundant; Lecane bulla becomes numerous in samples taken near vegetation after disturbance by rough weather, or where blue‐green algae are abundant.The associations of rotifers at the stations on Lake Albert and in the other lakes have been compared by means of the Sorensen Index and the index of diversity. The highest diversity is found in situations with a high rate of flow, as at the mouth of the Victoria Nile, where the extra species are non‐planktonic forms swept into suspension by the current. This high diversity is associated with low numbers of individuals per unit volume. In Lake Albert rotifers are most consistently present and abundant at the mouth of the River Semliki, where the rate of flow is moderated by a large reed swamp. The middle of Lake Albert is poor in rotifers, and this may be related to the sparseness of planktivorous fish coupled with competitive elimination of the rotifers by larger crustacean zooplankters.The associations of rotifers in Lakes Kyoga and George are similar, and resemble one another more than they resemble the associations in their neighbouring deeper lakes. The association in Lake Kyoga also resembles the associations found in water of a similar depth at the northern end of Lake Albert.
Sisor rabdophorus—A study in adaptation and natural relationship: II. The interrelationship of the gas bladder, Weberian apparatus, and membranous labyrinth
Authors: Mahajan C. L. 
Published: August 2009

A detailed description of the gas bladder, the Weberian apparatus and the membranous labyrinthin Sisor rabdophorus is given. It has been shown that these structures show a number of specializations which can be correlated with the bottom‐living habits of the fish. Evidence has been brought forth to show that the Weberian mechanism continues to serve as an aid to hearing.It has been concluded that Günther's inclusion of Sisor in the group Hypostomatina along with certain loricariid and callichthyid genera is not a natural one and that Regan's (1911) and Berg's (1940) family Sisoridae is more indicative of natural relationships. That Sisor diverged early from the main stem of sisorid evolution, is further supported by this study.
Feeding appendages of the Euphausiacea (Crustacea)
Authors: Mauchline J. 
Published: August 2009

The Euphausiacea comprises about 85 species and the structure of the feeding appendages of 68 of these species is discussed here. A considerable uniformity is apparent in the appendages throughout the order but generic, and even in some cases, specific differences are evident. It is concluded from the study of the morphology of the appendages and the analyses of stomach contents that the majority of species in the genera Bentheuphwsia, Thysanopoda, Meganyctiphanes, Nyctiphanes, Pseudeuphausia, Euphausia, Tessara‐brachion and Thysanoessa are omnivorous; that is, they can feed by filtering material from the water and act as predators of small zooplankton, especially copepods. Species in the genera Nematoscelis, Nematobrachion and Stylocheiron can feed on bottom deposits and also by predation of zooplankton but the amount of filter‐feeding which they do may be limited because their mouthparts are not so well adapted for filtering as those of the previous group of genera.It is suggested, from the study of the appendages and several other features of the animals, that the genera Thysanopoda, Meganyctiphanes, and Euphausia are closely related to one another and that a similar relationship exists between the genera Nematoscelis, Nematobrachion and Stylocherion. The genera Nyctiphanes and Pseudeuphausia are probably more closely related to the Thysanopoda group of genera and the genera Tessarabrachion and Thysanoessa to the Nematoscelis group of genera.
A cinefluorographic study of mandibular movement during feeding in the rat (Rattus norvegicus)
Authors: Hiiemäe Karen M. , Ardran G. M. 
Published: August 2009

The anatomy of the masticatory apparatus, and particularly of the mandibular joints, has led to the view that mandibular movement in the Rodentia is predominantly propalinal, or forwards and backwards in direction. As part of an investigation into the mechanism of function of the mandibular joints in these animals, the feeding behaviour of “August” strain and “Wistar” rats was examined by cinephotography and cinefluorography. The rats were trained to feed on barium sulphate impregnated biscuit and animal cake and to drink radio‐opaque liquids. Cinefluorographic recordings of ingestion, mastication, deglutition and of drinking were taken in both the lateral and dorso‐ventral projections.Analysis of the recordings has shown a fundamental separation of ingestive and masticatory activity in the rat, which can be attributed to the morphology of the jaws and particularly to the disparity in the lengths of the mandibular and maxillary diastemas. To bring the incisor teeth into occlusion for ingestion, the mandible is brought forward through the rest position and the condyle into articulation with the anterior part of the fossa. In mastication the condyle is moved backwards to bring the molar teeth into occlusion and the condyle into articulation with the posterior articular facet on the fossa. Once the mandible has been moved into the appropriate position for either ingestion or mastication and deglutition, the movements involved in the separation or chewing of the food are cyclical with combined horizontal and transverse movements as well as the fundamental vertical movement acting to open and close the mouth. The basic movement of ingestion carries the mandibular incisors upwards and forwards across the lingual surfaces of the maxillary incisors, so separating the bite. The grinding stroke of mastication is a horizontal movement carrying the mandibular molars anteriorly across the maxillary.
Studies on the helminth parasites of the Long‐tailed field mouse, Apodemus sylvaticus sylvaticus from Wales
Authors: Lewis J. W. 
Published: August 2009

The incidence and degree of infestation of the Long‐tailed field mouse, Apodemus sylvaticus with helminth parasites have been studied from a rough grassland and woodland area, Aberystwyth and from Skomer Island in Wales. With few exceptions, adult mice were more heavily infested than juveniles.In Aberystwyth, where the composition of the helminth fauna was found to be more varied than that from the island of Skomer, three species of helminths, one digenean and two nematodes, showed evidence of seasonal variation in the degree of infestation of mice. The factors affecting this fluctuation in parasite numbers throughout the year are discussed.It is suggested the distribution of helminths in the mouse population may be represented by a negative binomial, indicating that the infective eggs, larvae or intermediate hosts of the respective helminths were aggregated in their distribution in the selected areas of study.
Studies on the helminth parasites of voles and shrews from Wales
Authors: Lewis J. W. 
Published: August 2009

The incidence and degree of infestation of the Bank vole, Clethrionomys glareolus, the Skomer vole, C. skomerensis, the Common shrew, Sorex araneus and the Pygmy shrew, S. minutus have been studied from a rough grassland and woodland area, Aberystwyth and from Skomer Island in Wales. In addition, small numbers of the Short‐tailed vole, Microtus agrestis and the Water shrew, Neomys fodiens were examined for helminth parasites, when they became available. Seven new host records and six new British records are listed. The number of species of helminths in shrews, which consisted largely of digeneans and cestodes, was greater than that in voles. This is undoubtedly linked with differences in the feeding habits of the two hosts.In Aberystwyth, where the composition of the helminth fauna was found to be more varied than that from Skomer Island, one species of nematode showed evidence of seasonal variation in the degree of infestation of Clethrionomys glareolus and four species, one digenean, two cestodes and one acantocephalan in Sorex araneus. The factors affecting this seasonal fluctuation in parasite numbers are discussed.
Some observations on the development and cyclic changes of the oöcytes in a brooding starfish, Leptasterias hexactis
Authors: Chia Fu‐Shiang 
Published: August 2009

There are two ovaries in each arm and each ovary bears a single oviduct which opens orally at the interradial angle. The ovarian wall consists of three layers: mesothelium, muscular‐connective tissue layer and germinal epithelium. The haemal space between the germinal epithelium and muscular‐connective tissue layer is filled with a PAS positive fluid. It is suggested that this space may provide storage and transportation of nutrient to the germ cells.The oögonium, situated along the germinal epithelium, is distinguished from the surrounding follicle cells by its clear cytoplasm and large nucleus with a single nucleolus. It measures 10 to 15 μ in diameter.The development of primary oöcytes is divided into premeiotic, growth and germinal vesicle migration stages. The distribution of mitochondria seems to indicate the existence of a definite polarity in the young oöcytes; but this soon disappears at the beginning of vitellogenesis. Morphological evidence seems to suggest that some of the yolk granules may be synthesized first in follicle cells and then transferred into the oöcyte. Histochemical tests indicate that the yolk platelet is a carbohydrate‐protein‐lipid complex.The first meiotic division occurs six hours after sperm penetration and the second meiotic division follows two hours later.Monthly measurement of the oöcyte throughout a year indicates a well‐defined annual spawning cycle; however, the growth of an oöcyte from an oögonium to a mature oöcyte requires about two years.
Aspects of the respiratory physiology of Tubifex tubifex in relation to its ecology
Authors: Palmer Maureen F. 
Published: August 2009

An ecological survey of the London Basin of the Thames was undertaken in an attempt to define the limits of distribution of tubificids and to correlate their distribution with the oxygen concentration and the salinity.The oxygen consumption of Tubifex tubifex has been measured at various oxygen concentrations to define precisely the critical level.Measurements of oxygen consumption at various salinities have also been carried out, since salinity varies considerably over those parts of the estuary where tubificids are found. Salinity tolerance experiments were carried out in an attempt to determine the reason for the downstream limit of London Bridge.
A taxonometric investigation of the Alluroididae (Oligochaeta)
Authors: Jamieson B. G. M. 
Published: August 2009

By computation of coefficients of similarity and construction of dendrograms by the highest single linkage, average linkage and complete linkage methods, the interrelationships of five members of the Alluroididae have been assessed together with their affinities with Syngenodrilus lamuensis Smith & Green (1919) and Drawida grandis (Bourne), 1894 (Monili‐gastridae). The latter two species were included in the study because Syngenodrilus was placed in the Moniligastridae by its authors and was made the basis of an elaborate hypothesis of moniligastrid evolution by Stephenson (1930) while Gates (1945) argued cogently for its inclusion in the Alluroididae. To assist in “calibrating” phenon levels in terms of taxonomic ranks, species from other families were included in the taxonometric comparisons, namely Pygmaeodrilus affinis and Eukerria saltensis (Ocnerodrilidae), Digaster armifera (Megascolecidae) and an unnamed species of the Tubificidae.The three linkage methods reveal the same interrelationships within the five alluroidids and justify the following taxonomic changes*. Alluroides tanganyikae s. Brinkhurst (1964), from Mt Elgon, is removed from A. tanganyikae Beddard (1906) and made the nominal subspecies of a new species, A. brinkhursti; new material, from Ethiopia, is placed in this species as the new subspecies A. brinkhursti abyssinicus; Alluroides americanus Brinkhurst (1964), from Argentina, is made the type of a new monotypic genus Brinkhurstia; a new species from the Transvaal is placed in a new monotypic genus, as Standeria transvaalensis; Alluroides, Brinkhurstia and Standeria are placed in the subfamily Alluroidinae, while the Syngenodrilinae, which show in all dendrograms a very low phenetic affinity with the Moniligastridae, are transferred to the Alluroididae. Descriptions drawn from the author's examination of type material are given for all the new taxa together with an emended description of A. pordagei Beddard (1894), the type species of the genus, and a synopsis of descriptions of Syngenodrilus lamuensis. A key to species of the Alluroidinae is given in conjunction with a discussion of the comparative morphology of all species of the subfamily.The highest linkage dendrogram, and less certainly, the average and complete linkage dendrograms suggest that the Ocnerodrilidae and Megascolecidae s. Gates (1959) are only distinct at the subfamily level and the author reiterates earlier doubts (Lee, 1959; Jamieson, 1963) that the Octochaetidae and Acanthodrilidae, which are distinguished from each other by their nephridia (Gates, 1959), are valid groups or that they should be excluded from the Megascolecidae s. lat.
Spirorbinae (Polychaeta: Serpulidae) of the Galapagos Islands*
Authors: Bailey Julie H. , Harris M. P. 
Published: August 2009

Twelve species, six of which are new, are recorded from shores andshallow water. The most generally abundant are Spirorbis tricornigerus Rioja, S. bushi Rioja (both dextral with tube incubation), S. regalis sp. n., S. tuberculatus sp. n. (both sinistral with opercular incubation) and S. placophora sp. n. (sinistral, with tube incubation). Other sinistral species include S. claparedei Caullery & Mesnil, S. berkeleyana Rioja, S. bidentatus sp. n., and S. translucens sp. n. Dextral species include S. marioni Caullery & Mesnil, S. pagenstecheri Quatrefages and S. unicornis sp. n. The new species mentioned above have been described by the author named first.The Spirorbis fauna seems to be quite like that of Mexico and S. America, from which repeated introductions have probably occurred, perhaps on stones buoyed by seaweeds and drifting on the Peruvian and El Nino currents. Its considerable diversity is not attributed to speciation within the archipelago.
Moult in birds of the Australian dry country relative to rainfall and breeding
Authors: Keast Allen 
Published: August 2009

The annual moult of some 20 species of birds inhabiting the dry western section of New South Wales is studied, emphasis being on time of commencement, duration, finishing time, and the interrelationship of breeding and moulting. Primary feather replacement is taken as the main criterion.The moult begins in most species in November and is completed in February or March. The duration ranges from about three to five months, being four to four and a half months in most species. This is materially longer than the six to eight weeks commonly taken by small passerines in the Northern Hemisphere. A longer, and more protracted moult is considered to be of adaptive value in a dry and somewhat unpredictable environment, reducing the physiological stress on the bird.Migratory species have later, and somewhat shorter moults, than resident ones. Those of three aerial‐feeding muscicapids are relatively short. Small birds commonly have shorter, and larger birds more protracted, moults.The moult is much more regular in its occurrence than breeding, which can only occur in those springs when seasonal conditions are reasonably good. Thus the “postnuptial” moult takes place whether breeding has occurred or not. This suggests a measure of direct photoperiodic control. On the other hand there are instances of the moult starting up to two or three weeks earlier than usual when (a) there is an early termination to successful spring breeding and, (b) severe drought conditions render spring breeding impossible. The onset of the moult may apparently be delayed by up to a couple of weeks when (a) spring breeding is protracted or (b) it is delayed. This indicates a measure of antagonism between the “moulting” and reproductive hormones in some species.Good rain in mid‐summer will induce out‐of‐season breeding in many species, notwithstanding that they may be in full moult at the time. This particularly applies in years when spring breeding was impossible. No data is available as to whether or not this causes a slowing‐down, or interruption, to the moult although, it will be noted, Carter (1923) suggests this to be the case. In some species “mid‐moult” breeding did not mean any delay in the completion of the moult but, in others, it apparently did so. The ability to moult and breed simultaneously is obviously an important adaptation, permitting the birds to make maximum use of a time of food abundance.Attention is drawn to adaptational parallels in the moult of certain dry country birds of Australia, Africa, and South America.
The sea anemone Calliactis tricolor and its association with the Hermit crab Dardanus venosus
Authors: Cutress Charles E. , Ross Donald M. 
Published: August 2009

The association of certain sea anemones and hermit crabs is established in different ways according to the species involved. The present study shows that the behaviour patterns of the two partners in associations between Calliactis tricolor (Lesueur) and Dardanus venosus (H. M. Edwards) in the Caribbean are similar to those seen in the Mediterranean C. parasitica and D. arrosor.Although about half the crabs display an active behaviour pattern in laboratory trials, the anemone frequently settles on shells unaided and most C. tricolor respond to molluscan shells by clinging with their tentacles until the pedal disc can be attached. As a rule it is necessary for the anemone to relax and to cling to the shell if the crab is to be successful in transferring the anemone to its shell.The behaviour patterns of D. venosus include a distinctive tapping of the edge of the base of C. tricolor after which the anemone is pulled or lifted off and transferred to the shell. An experimenter can also cause the anemone to relax and to detach itself by tapping the edge of the base with plastic rods after the manner of the crab.The mechanisms by which the tentacles of Calliactis cling to, and by which the base settles upon, shells still remain to be elucidated. The participation of nematocysts in these processes could not be demonstrated in this study. C. tricolor is found on some other pagurid and non‐pagurid crabs in various localities. These associations need to be investigated fully in order that the behaviour patterns of C. tricolor may be correctly interpreted and compared with those of other species of Calliactis.
The distribution of some hydrolytic enzymes in the cells of the digestive gland of certain lamellibranchs and gastropods
Authors: Sumner A. T. 
Published: August 2009

Five hydrolytic enzymes (acid phosphatase, aryl sulphatase, β‐glucuronidase, N‐acetyl‐β‐glucosaminidase, and non‐specific esterase) have been studied histochemically in the cells of the digestive gland of Mytilus edulis, Helix aspersa, and certain other lamellibranchs and gastropods. All the enzymes studied have basically similar distributions.In the digestive cells, the enzymes occur in cytoplasmic granules which are believed to be primary lysosomes; in vacuoles which contain phagocytosed food material; and in vacuoles containing lipofuscin granules, which are the residues of digestive activity.In the basiphil cells of M. edulis, most of the enzymes are localized in a few cytoplasmic granules; non‐specific esterase, however, is found throughout the cytoplasm. In the calcium cells of H. aspersa and the other pulmonate gastropods studied, the enzymes are either in cytoplasmic granules, or distributed diffusely throughout the cytoplasm. Acid phosphatase is also found in the calcium spherules, especially in H. aspersa.In the excretory cells of H. aspersa and the other pulmonates studied, the enzymes are found in granules in the cytoplasm, and in the lipofuscin granules which lie in the vacuoles of these cells.