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The mollusc fauna of the early Middle Miocene (Langhian) intramontane Alpine Lake Groisenbach is described for the first time. The shells derive from the Feistring Formation in the Aflenz Basin in Austria, which was covered by Lake Groisenbach. The assemblage is moderately diverse with 12 gastropod and 2 bivalve species, suggesting shallow lacustrine and fluvial settings. Among the gastropods, only Theodoxus crenulatus (Klein, 1853) is known from other Miocene localities, whilst all other species are documented so far only from Lake Groisenbach. None of the Early and Middle Miocene lake systems of the Alpine-Carpathian Foredeep and the Balkan Peninsula displays any faunistic resemblance with this new fauna. Even coeval lake faunas from the close-by Graz Basin have no species in common with Lake Groisenbach. This pattern points to a surprising endemicity and biogeographic fragmentation in the Central European freshwater systems during the Early and Middle Miocene. The uniqueness of the newly described fauna is also indicated by the completely erratic occurrence of the otherwise African-Mediterranean genus Bulinus, which is unknown from all other central European Miocene freshwater systems. Emmericia roetzeli Harzhauser and Neubauer nov. sp., Nematurella zuschini Neubauer and Harzhauser nov. sp., Romania fastigata Neubauer and Harzhauser nov. sp., Odontohydrobia groisenbachensis Neubauer and Harzhauser nov. sp., Odontohydrobia pompatica Neubauer and Harzhauser nov. sp., Odontohydrobia styriaca Harzhauser and Neubauer nov. sp., Planorbis austroalpinus Harzhauser and Neubauer nov. sp., Gyraulus sachsenhoferi Harzhauser and Neubauer nov. sp., Bulinus corici Harzhauser and Neubauer nov. sp., Ferrissia crenellata Harzhauser and Neubauer nov. sp. and Stagnicola reinholdkunzi Harzhauser and Neubauer nov. sp. are introduced as new species.

Rhodamine B and Rhodamine WT are fluorescent dyes commonly used as tracers in hydrological investigations. Since introducing intensely red substances into rivers raises understandable doubts of ecological nature, the authors aimed at examining the influence of these dyes on small water fauna using bioindication methods. Quantitative results, calculated with the use of Bliss-Weber probit statistical method, were achieved by means of standardized ecotoxicological tests containing ready-to-hatch resting forms of fairy shrimp (Thamnocephalus platyurus). Qualitative studies included observation of water flea crustacean (Daphnia magna) and horned planorbis snail (Planorbis corneus), both typically present in rivers and representative for temperate climate, as well as guppy fish (Poecilla reticulata), paramecium protozoan (Paramaecium caudatum) and the above-mentioned fairy shrimp. The investigation revealed that both dyes in concentrations used for hydrological purposes are low enough to exert almost no toxic impact on water fauna considered.

A survey of the larval stages (cercariae and metacercariae) of trematodes (Digenea) found in planorbid snails in Central Europe (Austria, Czech Republic, south-east Germany, Hungary, Poland and the Slovak Republic) is presented based on a study of 7,628 snails of 12 species examined between 1998-2006. A total of 34 trematode larval stages, comprising cercariae of 28 species and metacercariae of seven species (one species occurred both as cercaria and metacercaria) of nine families were found in 898 (11.5%) snails of eight species. The dominant cercariae were those belonging to the Rubenstrema exasperatum (Rudolphi, 1819)/Neoglyphe locellus (Kossack, 1910) species complex, Tylodelphys excavata (Rudolphi, 1803) and Echinostoma spiniferum (La Valette, 1855) sensu Nasincová (1992), all from Planorbarius corneus (Linnaeus). Almost the same spectrum of cercariae of the families Echinostomatidae, Plagiorchiidae and Omphalometridae was found in the present study as in previous reports; however, a considerably lower spectrum of cercariae of the families Diplostomidae and Strigeidae was recorded. The most frequent metacercariae were those of Echinoparyphium aconiatum Dietz, 1909, Neoglyphe locellus and Moliniella anceps (Molin, 1859), all occurring mainly in P. corneus. The most heavily infected snail species was P. corneus, followed by Planorbis planorbis (Linnaeus) and Segmentina nitida (Müller). The widest spectrum of trematode species was found in P. planorbis and P. corneus. Forty-two cercariae identified to the species level belonging to 15 families, plus an additional 43 taxa recorded under generic or provisional names, were reported from 11 species of planorbids in previous studies carried out in Central Europe. However, the actual number of trematode species occurring in the planorbid snails is probably much lower, because many, if not most, larval stages reported under provisional names or unidentified to the species level may be conspecific with identified adult forms. A key to the cercariae and metacercariae recorded from planorbids in Central Europe, together with illustrations of those species encountered most frequently in the field, is provided to facilitate identification.

Tadpole impact on periphytic algae was estimated with an exclosure experiment in the field. Algae growth on control (exposed) and experimental (netted-in) Perspex plates was measured in 12 ponds in 1991 and 8 in 1993.An index of snail (Lymnea and Planorbis)presence in the ponds was used to correct their effect. Grazing pressure (difference in amount of algae between control and experimental plates)differed between ponds. The difference was correlated to amount of Rana tadpoles present in the pond. At the higher densities of tadpoles observed in the study ponds, the algae standing crop on exposed plates was about 50–75% of that on netted-in plates. These result demonstrate that there is potential for effects of exploitation competition in ponds with a high tadpole density.

The measurement and induction of mixed function oxyigenases (MFOs) of limnetic gastropods were investigated to estimate their suitability as biomarkers. A determination of MFO activities was performed through the measurement of ethoxyresorufin-O-dealkylase (EROD), pentoxy-(PROD) and benzoxyresorufin-O-dealkylase-activity (BROD). Optimal measuring conditions of these activities were investigated in preparations of the digestive gland of 4 species of limnetic gastropods. Results indicate that MFO-activity inhibiting substances are accumulating in the microsomal pellet, the fraction commonly used for the measurement of MFO-activities. Therefore, the fraction used for induction studies was the postmitochondrial supernatant (PMS). EROD, PROD, and BROD activity of Planorbis planorbis and Planorbis carinatus were measured after a treatment with Aroclor 1254 for 1-17 days. Maximal induction of EROD and PROD were 6 and 10 times the value in the control group of P. carinatus, respectively induction in P. planorbis was lower. BROD-activity could not been measured in P. planorbis. In P. carinatus, BROD-activity increased to a maximum of 2 times after treatment with Aroclor 1254. The level of induction of EROD-activity is comparable to results described in analog studies with fish.

A radiotracer technique involving 51Cr was used to monitor the egestion rates of A. fluviatilis and P. contortus.

1. Monthly quantitative samples of the invertebrate fauna (except Protozoa) in a small pond were taken over a period of three years. During one year, insect emergence traps were in operation. Water temperatures were recorded during the investigation. 2. The most abundant organisms in the pond were Phaenocora typhlops, Limnodrilus hoffmeisteri and Chaoborus crystallinus. Certain species of Micro-Crustacea and Chironomidae were also abundant but these groups have been dealt with elsewhere (see p. 66). Dendrocoelum lacteum, Polycelis nigra, Helobdella stagnalis, Lumbriculus aariegatus, Tubifex tubifex, Planorbis complanatus, and Asellus meridianus also occurred in considerable though lower numbers; other species occurred in low numbers. 3. The life-cycles and changes in numbers of the more numerous species are considered. The life-histories of D. lacteum, P. nigra, H. stagnalis, P. complanatus, A. meridianus are in agreement with published information. P. typhlops is seasonal in occurrence, being active from May to Sept. inclusive. Times of emergence of adults of various insect species agree with information available in the literature. 4. The life-cycle of L. hoffmeisteri in the pond is as follows: young worms hatch in spring/summer and form the bulk of the population from April to July/Aug; they mature from Aug. onwards and breeding starts in earnest from Feb./March. The life-cycle of T. tubifex is as follows: breeding starts in Feb., recruitment of young takes place from April till June, and these start to mature in Nov./Dec. It is not certain if some animals which breed in the spring/early summer survive to breed the following year. 5. The life-cycle of C. crystallinus appears to be as follows: first instars present from May to Oct., second instars from May to Dec., third instars from June till following Jan., fourth instars all the year round, pupae from May till Aug., and eggs from May to Sept. Adult emergence takes place from late April till mid-Sept. 6. A six-week drought in Oct/beginning Nov. in the second year of the investigation caused considerable mortality in most species, but most survived with only a few exceptions.

Sixteen species of aquatic snails of four families were tested by quantitative technique under standardized conditions for their suitability as intermediate hosts for Angiostrongylus cantonensis. These species were the planorbid snails Biomphalaria glabrata, Biomphalaria alexandrina, Planorbis planorbis, Planorbis intermixtus, Bulinus truncatus, Bulinus contortus, Bulinus africanus, Bulinus tropicus and Helisoma sp.; the lymnaeid snails Lymnaea natalensis, Lymnaea tomentosa, Lymnaea stagnalis, and Stagnicola elodes; the physid snail Physa acuta (an Egyptian and a German strain) and the ampullariid snails Marisa cornuarietis and Lanistes carinatus. All these snail species proved to be susceptible to infection with A. cantonensis, and first stage larvae reached the infective third stage in all of them. However, the rate and intensity of infection varied with different species. B. glabrata was the most susceptible snail species with a 100% infection rate and an average percentage recovery of third stage larvae of 26.1. This was followed by S. elodes and B. africanus, with a 100% infection rate and an average percentage recovery of third stage larvae of 15.6 and 14.6 respectively. The rest of snail species proved to be less susceptible. For comparative evaluation of the suitability of the various snail species as intermediate hosts of A. cantonensis a "Capacity Index" was determined. This index should provide a useful method for the evaluation of the suitability of various snails as intermediate hosts of nematode parasites under standardized conditions in the laboratory.

Radiotracer and gravimetric techniques were used to investigate the effects of starvation, temperature, body size and food quality on both the ingestion rates and absorption efficiencies of A. fluviatilis (an algal grazer) and P. contortus (a detrivore which utilises the bacterial fraction of its food). In the face of food supply disturbance snails showed a considerable potential for adaptation. Both intestion rates and absorption efficiencies increased with starvation, and ingestion rate increased with reductions in food quality. Absorption efficiencies were independent of temperature and Q10 values for absorption rates suggested that snails showed some acclimation to temperature disturbance. Food absorption was linearly related to body surface area but absorption efficiencies were to a large extent independent of age and size.

Isolated buccal ganglia of Planorbis corneus are capable of generating a feeding rhythm. In the present work, "rhythmic" neurons of different groups (see Arshavsky et al. 1988a) have been extracted, by means of an intracellular microelectrode, from the buccal ganglia. (1) After extraction, efferent neurons of groups 3, 5, 7, 9 and most group 4 neurons generated repeated spikes at a frequency controlled by a polarizing current. Any periodic oscillations, similar to those during feeding rhythm generation, were absent in these isolated neurons. It is concluded, therefore, that these neurons are "followers", that is, their rhythmic activity before extraction is determined by synaptic inputs from other neurons of the ganglia. (2) Isolated interneurons of groups 1 and 2 generated slow periodic oscillations similar to those observed in these neurons before their extraction. Subgroup 1e neurons generated smoothly growing depolarization accompanied by increasing spike activity; this depolarization was periodically interrupted by abrupt hyperpolarization, after which a new cycle started. Subgroup 1d neurons periodically generated short series of spikes. Group 2 neurons periodically generated a rectangular wave of depolarization with spike-like oscillations on its top. These results suggest that feeding rhythm generation in Planorbis is based on the endogenous rhythmic activity of group 1 and 2 neurons. (3) A pulse of hyperpolarizing current injected into an isolated neuron of subgroup 1e stopped the growth of depolarization in the neuron and reinitiated the process. This property as well as the character of the synaptic interactions of the interneurons (group 1 neurons excite those of group 2, while those of group 2 inhibit group 1 neurons; Arshavsky et al. 1988b) determine the alternating activity of groups 1 and 2.

The ecology of the aquatic gastropods Bithynia tentaculata, Gyraulus albus, Planorbis planorbis and Lymnaea peregra in North West England was investigated over 13 months at sites chosen for their wide range of water chemistry. Multiple regression analysis was used to determine the significance to the mollusc distributions of a variety of physico-chemical factors. Biotic factors were not considered. The species had similar life cycles, with little difference between populations within a species. B. tentaculata could live for over a year, and the major water chemistry variable was potassium (+), where the sign is that of the regression coefficient. G. albus could also survive into a second year and the major variable was mud substratum type (+). Rock substratum type (-) was the most important factor for P. planorbis. There was a slight difference in the life cycles of L. peregra in hard and medium compared with soft waters and the major water chemistry variable was magnesium (-).

Hilgendorf’s (1866) publication on the phylogenyof Planorbis multiformis from Steinheim, Swabian Mountains, is one of the most important contributions of paleontology to early Darwinism. At the same time it helped to lay the foundation for paleontological phylogenetics. Hilgendorf’s unpublished dissertation of 1863, the newly rediscovered collection to his dissertation and the document-file ofHilgendorf’s graduation from Tubingen University help to trace back the origin of Hilgendorf’s ideas.Hilgendorf’s collection contains the oldest phylogenetic tree, which is known so far.

In the buccal ganglia of the freshwater mollusk Planorbis co~'neus protein synthesis takes place most intensively in thebodies of nerve cells. Protein synthesis in giant neurons takes place with equal intensity both in cytoplasm and nucleus, 60% of the total mass of sulfur-containin g protein being produced by the cytoplasm. Protein leaves the neuron body principally along the axon. It migrates along the axon at a rate of about 0.2mm/day. Giant neurons of the buceal ganglia are characterized by very high electrical activity, giving way periodically (at intervals of 3-5 sec) to deep and prolonged (about 1 see) inhibition. This type of periodic unit activity continues substantially unchanged for up to 20 hr if the surrounding isotonic solution is constantly renewed.

Locomotion in the Pulmonata may have two, distinct, negative effects on total metabolism. Energy losses may occur via mucus secretions and also as a result of muscular and ciliary activities. These aspects of pulmonate metabolism were investigated in two freshwater species; Ancylus fluviatilis and Planorbis contortus. The former is a herbivore which feeds on periphyton and the latter is a detrivore which appears able to make use of bacteria.Speed of movement was influenced by starvation time, food availability, and water movement, although the extent to which these factors affected locomotion showed some variation with species. In still conditions P. contortus moved more rapidly than A. fluviatilis whereas the converse occurred under conditions of more violent water movement. During deprivation, however, both species showed similar responses in that their rate of locomotion increased to some maximum and then fell, and their pattern of movement became more random. These strategies were explained in terms of fitness.Under conditions of satiation locomotion had a measurable quantitative effect on P. contortus only, and contributed ca. 20% to routine metabolism. Nevertheless, under conditions of starvation locomotion influenced the respiratory metabolism of both species and in this case there were clear differences between the respiratory rates of constrained and non-constrained subjects. These results were used to explain certain differences recorded by earlier workers on the relationship between starvation and respiration in freshwater snails.Energy losses via mucus secretions were found to make a significant contribution to snail energetics, representing between 13-32% of the energy absorbed across the gut wall. However, the potential energy thus released may not be completely lost from the secreting system because mucus was found to stimulate the growth of those bacteria which are preferentially ingested by P. contortus. Consequently, mucus may play a provendering role and should not be ignored as a vehicle of biologically useful energy in aquatic or terrestrial ecosystems.

The study of the flood-waters revealed that the breach of irrigation channels due to heavy downpour, triggered the floods, as the first flood-waters largely contained characteristic riverine fauna. Later on, the riverine fauna was outnumbered by pond fauna indicating the overflow from ponds, adding to the amount of flood-waters. The flood-waters play a significant role in the distribution of animals in general and vectors in particular. The chief vectors included Cyclops, Lymnaea, Planorbis and five genera of fishes. Pockets of stagnant flood-water provide a breeding ground for mosquitoes to create a future nuisance. The faunal study of flood-waters offers a proof to their origin, which otherwise requires a manual survey.

I THINK I informed you about two years ago of the discovery of a bed of plants, with leaves, and a great variety of seeds, in this locality; also the wings of a Libellula, and the beak of a bird. As little interest was attracted, I have not hitherto informed you of the subsequent finding of a bed of insects—flies, gnats, and the larva and pupa of the latter, the larva in countless thousands—also the wings, in great numbers, of a variety of flies, butterflies, and one or two grasshoppers ; also a wing resembling that of the Mole Cricket. There are, likewise, two or three beetles. The insects and wings are frequently associated with a very pretty Lymnea, in considerable numbers, and an occasional Planorbis, both retaining a high polish. I have also noticed a solitary small white Cyclostoma in the same bed. There are, I think, two feathers among the specimens obtained. Perhaps, as some interest has been shown in a similar discovery in Scotland, some of your readers may like to be informed of this. I am much indebted to the Rev. T. G. Bonney, of St. John's College, Cambridge, to whom you referred me, for advice and encouragement in examining these beds.

IN the short notice in NATURE (vol. xiii. p. 257) of my paper on the Evolution of Haemoglobin, in the Quarterly Microscopical Journal, it is said that my conclusions are mainly based on a small difference in the wave-length of the absorption-bands of the spectrum of the red blood of Planorbis. This is, however, a very small part of the question. The principal results are that haematin is first met with in the bile of many pulmoniferous molluscs in an abnormal state, quite unfit to serve the purposes of respiration, but easily changed into the normal, which could, and probably does in some cases, perform that function. Then in the blood of Planorbis we have a solution of a haemoglobin, in which the haematin is combined with an albuminous constituent coagulating at the low temperature of 45° C., and finally we come to the normal haemoglobin existing as red corpscules, containing an entirely different albuminous constituent, coagulated at about 65° C. In all these changes in the condition of the si me fundamental radical, the oxygen carrier becomes of more and more unstable character, and more fitted for the purposes of respiration, as we advance from lower to higher types, as though advantage had been taken of every improvement due to modified chemical or physical constitution.

I OBSERVE in NATURE (vol. xi. p. 394) a rote from the Saar und Mosel Zeitung on the introduction of a mollusc into the Moselle near Tieves. Though the name of the species is not mentioned, I presume that Dreissena polymorpha is the mollusc in question, a species known to inhabit Britain since 1824, and supposed to have been introduced with timber from Eastern or Northern Europe. It is exceedingly prolific. An instance of how this species may be introduced came under my notice a few years ago. A friend showed me some shells that he had found attached to logs of wood lying on a railway truck. These proved to be alive when put into a cup of water; and if the logs in question had been deposited on the banks of the Tay within reach of the tide, as is often the case (I should have said that the truck was on a siding near Perth Harbour), we would no doubt have found Dreissena in abundance in the course of a few years. As this mollusc lives in brackish water as well as in fresh, it is no doubt in a manner similar to what I have mentioned that it has been introduced into and spread through Britain. Another shell, Planorbis dilatatus, a North American species, was found a few years ago living in a canal near Manchester, and is supposed to have been introduced with raw cotton. Recently another case of importation of living shells came under my notice. When looking at some bales of Typha from the Nile, imported into Aberdeenshire as a material for paper manufacture, I observed some shells sticking in the dry mud adhering to the roots of the Typha. On putting some of these into water they were found to be alive, though a good many months had elapsed since the Typha had been gathered. The shells appear to belong to Bythinia, but I have not yet determined the species. It is, perhaps, not very likely that if these shells had found their way into the Aberdeenshire rivers they would have survived.