France the French Republic, is a country whose territory consists of metropolitan France in Western Europe and several overseas regions and territories. The metropolitan area of France extends from the Mediterranean Sea to the English Channel and the North Sea, from the Rhine to the Atlantic Ocean, it is bordered by Belgium and Germany to the northeast and Italy to the east, Andorra and Spain to the south. The overseas territories include French Guiana in South America and several islands in the Atlantic and Indian oceans; the country's 18 integral regions span a combined area of 643,801 square kilometres and a total population of 67.3 million. France, a sovereign state, is a unitary semi-presidential republic with its capital in Paris, the country's largest city and main cultural and commercial centre. Other major urban areas include Lyon, Toulouse, Bordeaux and Nice. During the Iron Age, what is now metropolitan France was inhabited by a Celtic people. Rome annexed the area in 51 BC, holding it until the arrival of Germanic Franks in 476, who formed the Kingdom of Francia.
The Treaty of Verdun of 843 partitioned Francia into Middle Francia and West Francia. West Francia which became the Kingdom of France in 987 emerged as a major European power in the Late Middle Ages following its victory in the Hundred Years' War. During the Renaissance, French culture flourished and a global colonial empire was established, which by the 20th century would become the second largest in the world; the 16th century was dominated by religious civil wars between Protestants. France became Europe's dominant cultural and military power in the 17th century under Louis XIV. In the late 18th century, the French Revolution overthrew the absolute monarchy, established one of modern history's earliest republics, saw the drafting of the Declaration of the Rights of Man and of the Citizen, which expresses the nation's ideals to this day. In the 19th century, Napoleon established the First French Empire, his subsequent Napoleonic Wars shaped the course of continental Europe. Following the collapse of the Empire, France endured a tumultuous succession of governments culminating with the establishment of the French Third Republic in 1870.
France was a major participant in World War I, from which it emerged victorious, was one of the Allies in World War II, but came under occupation by the Axis powers in 1940. Following liberation in 1944, a Fourth Republic was established and dissolved in the course of the Algerian War; the Fifth Republic, led by Charles de Gaulle, remains today. Algeria and nearly all the other colonies became independent in the 1960s and retained close economic and military connections with France. France has long been a global centre of art and philosophy, it hosts the world's fourth-largest number of UNESCO World Heritage Sites and is the leading tourist destination, receiving around 83 million foreign visitors annually. France is a developed country with the world's sixth-largest economy by nominal GDP, tenth-largest by purchasing power parity. In terms of aggregate household wealth, it ranks fourth in the world. France performs well in international rankings of education, health care, life expectancy, human development.
France is considered a great power in global affairs, being one of the five permanent members of the United Nations Security Council with the power to veto and an official nuclear-weapon state. It is a leading member state of the European Union and the Eurozone, a member of the Group of 7, North Atlantic Treaty Organization, Organisation for Economic Co-operation and Development, the World Trade Organization, La Francophonie. Applied to the whole Frankish Empire, the name "France" comes from the Latin "Francia", or "country of the Franks". Modern France is still named today "Francia" in Italian and Spanish, "Frankreich" in German and "Frankrijk" in Dutch, all of which have more or less the same historical meaning. There are various theories as to the origin of the name Frank. Following the precedents of Edward Gibbon and Jacob Grimm, the name of the Franks has been linked with the word frank in English, it has been suggested that the meaning of "free" was adopted because, after the conquest of Gaul, only Franks were free of taxation.
Another theory is that it is derived from the Proto-Germanic word frankon, which translates as javelin or lance as the throwing axe of the Franks was known as a francisca. However, it has been determined that these weapons were named because of their use by the Franks, not the other way around; the oldest traces of human life in what is now France date from 1.8 million years ago. Over the ensuing millennia, Humans were confronted by a harsh and variable climate, marked by several glacial eras. Early hominids led a nomadic hunter-gatherer life. France has a large number of decorated caves from the upper Palaeolithic era, including one of the most famous and best preserved, Lascaux. At the end of the last glacial period, the climate became milder. After strong demographic and agricultural development between the 4th and 3rd millennia, metallurgy appeared at the end of the 3rd millennium working gold and bronze, iron. France has numerous megalithic sites from the Neolithic period, including the exceptiona
George Washington Tryon
George Washington Tryon Jr. was an American malacologist who worked at the Academy of Natural Sciences in Philadelphia. George Washington Tryon was the son of Edward K. Adeline Savidt. In 1853 he attended the Friends Central School in Philadelphia. In 1859, Tryon became a member of the Academy of Natural Sciences of Philadelphia, he was responsible for the construction of new buildings for the Academy in 1866, a section for malacology. In 1869 he became the conservator in this malacological section. In 1865, together with a group of American malacologists, he founded the American Journal of Conchology; this ended in 1872. In 1879 he started the Manual of Conchology; when he died, nine volumes of the first series had been published. From 1887 until 1888, his assistant was Henry Augustus Pilsbry. Thereafter, Pilsbry continued as editor of the ongoing multi-volume Manual of Conchology; the work was continued until 1935. Tryon named more than 5,600 new species, can be considered as one of the most prolific malacologists.
His important collection made the Academy of Natural Sciences of Philadelphia the center of malacological studies in the 19th century. The freshwater snail genus. Tryon published more than 1,000 books. Tryon G. W. 1861. List of American writers on recent conchology. With the titles of their memoirs and dates of publication. New York, Ballière Brothers, 440 Broadway. Tryon, G. W. 1862: Synopsis of the Recent species of Gastrochaenidae, a family of acephalous Mollusca. Proc. Acad. Nat. Sc. Philadelphia. Vol. 13:465-94 Tryon, G. W. 1862: A sketch of the History of Conchology in the United States. Am. Journ. Sc. Arts. 33 Tryon G. W. 1863. Notes on American fresh water shells, with descriptions of two new species. Proceedings of the Academy of Natural Sciences of Philadelphia, 14: 451–452. Tryon G. W. 1864. The complete writings of Constantine Smaltz Rafinesque on recent & fossil conchology. Edited by Wm. G. Binney and George W. Tryon Jr. – Correct spelling should be Constantine Samuel Rafinesque. The book includes all of Rafinesque's malacological plates.
Tryon G. W. 1865. Observations on the family Strepomatidae. American Journal of Conchology, 1: 97–135. Tryon G. W. 1865. Synonymy of the species of Strepomatidae of the United States. New York, Ballière Brothers, 520 Broadway, 100 pp. 2 plates. – Tryon G. W. 1866–1868. Monograph of the terrestrial Mollusca of the United States. American Journal of Conchology. 1866. 2: 218–277, plates 1–4. 1866. 2: 306–327, plates 5–6. 1867. 3: 155–181, plates 11–14. 1868. 3: 298–234, plates 14–17. Tryon G. W. 1870. A monograph of the fresh-water univalve mollusca of the United States. Turbidae, Physadae. Philadelphia. Tryon, G. W. 1872: Catalogue and Synonymy of the Recent species of the family Lucinidae. Proc. Acad. Nat. Sc. Philadelphia. Pages 82–96 Tryon G. W. 1873. American marine conchology: or, Descriptions of the shells of the Atlantic coast of the United States from Maine to Florida. Philadelphia, published by the author. Tryon G. W. 1882. Structural and systematic conchology: an introduction to the study of the Mollusca. Volume I.
Philadelphia, published by the author. Tryon G. W. 1882. Structural and systematic conchology: an introduction to the study of the Mollusca. Volume II. Philadelphia, published by the author. Tryon G. W. 1884. Structural and systematic conchology: an introduction to the study of the Mollusca. Volume III. Philadelphia, published by the author. Manual of Conchology and systematic, with illustrations of the species; the illustrations in this work were created by Dr. E. J. Nolan. Note: there are old synonyms in names of some volumes. 1879 – Volume 1. Cephalopoda. 1880 – Volume 2. Muricinae, Purpurinae. 289 pp. 70 plates. 1880–1881 – Volume 3. Tritoniidae, Buccinidae. 310 pp. 87 plates. 1882 – Volume 4. Nassidae, Volutidae, Mitridae. 1883 – Volume 5. Marginellidae, Columbellidae. 1884 – Volume 6. Conidae, Pleurotomidae. 1885 – Volume 7. Terebridae, Strombidae, Ovulidae, Doliidae. 1886 – Volume 8. Naticidae, Turritellidae, Caecidae, Turbonillidae, Pyramidellidae. 461 pp. 79 plates. 1887 – Volume 9. Solariidae, Trichotropidae, Cerithiidae, Littorinidae.
488 pp. 71 plates. Note: Solariidae is not a valid family today. Published in parts: 7 February 1887 – part 33, pages 1–64. 8 June 1887 – part 34, pages 65–128. 2 September 1887 – part 35, pages 129–224. 10 December 1887 – part 36, 36a, pages 225–488. 1888–1889 – Volume 10. Neritidae, Cyclostrematidae, Phasianellidae, Trochidae, Haliotidae, Pleurotomariidae. 322 pp. 69 plates. Published in parts: 16 March 1888 – part 37, pages 1–64. 1 July 1888 – part 38, pages 65–144. 1 October 1888 – part 39, pages 145–208. 3 January 1889 – part 40, pages 209–323. 1889 – Volume 11. Trochidae, Pleurotomariidae, Haliotidae. 519 pp. 67 plates. Note: Stomatiidae is a synonym for subfamily Stomatellinae in the family Trochidae. 1890 – Volume 12. Continued by Henry Augustus Pilsbry
A love dart is a sharp, calcareous or chitinous dart which some hermaphroditic land snails and slugs create. Love darts stored internally in a dart sac. Love darts are made in sexually mature animals only, are used as part of the sequence of events during courtship, before actual mating takes place. Darts are quite large compared to the size of the animal: in the case of the semi-slug genus Parmarion, the length of a dart can be up to one fifth that of the semi-slug's foot; the process of using love darts in snails is a form of sexual selection. Prior to copulation, each of the two snails attempts to "shoot" one darts into the other snail. There is no organ to receive the dart; the dart does not fly through the air to reach its target however. The love dart is not a penial stylet; the exchange of sperm between both of the two land snails is a separate part of the mating progression. Recent research shows that use of the dart can favor the reproductive outcome for the snail, able to lodge a dart in its partner.
This is because mucus on the dart introduces a hormone-like substance that allows far more of its sperm to survive. Love darts known as shooting darts, or just as darts, are shaped in many distinctive ways which vary between species. What all the shapes of love darts have in common is their harpoon-like or needle-like ability to pierce. Mating begins with a courting ritual. For example, in land snails of the genus Helix, including the escargot Helix pomatia, the common garden snail Helix aspersa, copulation is preceded by an elaborate tactile courtship; the two snails circle around each other for up to six hours, touching with their tentacles, biting lips and the area of the genital pore, which shows some preliminary signs of the eversion of the penis. As the snails approach mating, hydraulic pressure builds up in the blood sinus surrounding the organ housing the dart; each snail manoeuvres to get its genital pore in the best position, close to the other snail's body. When the body of one snail touches the other snail's genital pore, it triggers the firing of the dart.
The darting can sometimes be so forceful. It can happen that a dart will pierce the body or head and protrude on the other side. After both snails have fired their darts, the snails exchange sperm. A snail does not have a dart to fire the first time it mates, because the first mating is necessary to trigger the process of dart formation. Once a snail has mated, it fires a dart before some, but not subsequent matings. A snail mates without having a dart to use, because it takes time to create a replacement dart. In the case of the garden snail Cornu aspersum, it takes a week for a new dart to form; the dart is shot with some variation in force, with considerable inaccuracy, such that one-third of the darts that are fired in Cornu aspersum either fail to penetrate the skin, or miss the target altogether. Snails have only simple visual systems and cannot see well enough to use vision to help aim the darts. Although the existence and use of love darts in snails has been known for at least several centuries, until the actual function of love darts was not properly understood.
It was long assumed that the darts had some sort of "stimulating" function, served to make copulation more likely. It was suggested that darts might be a "gift" of calcium; these theories have proved to be incorrect. A closer look into the behavior of Cornu aspersum, shows that it is not the mechanical action of the dart that increases paternity in sperm donors but instead the mucus that coats the dart; the mucus carries an allohormone, transferred into the recipient snail’s hemolymph when the dart is stabbed. This allohormone reconfigures the female component of the reproductive system in the receiving individual: the bursa copulax is closed off, the copulatory canal is opened; this reconfiguration allows more sperm to access the sperm storage area and fertilize eggs, rather than being digested. This increases the shooter’s paternity; the love dart known as a "gypsobelum", is made of calcium carbonate, secreted by a specialized organ within the reproductive system of several families of air-breathing snails and slugs in terrestrial pulmonate gastropod mollusks within the clade Stylommatophora.
Darts can range in size from about 30 millimetres long in the larger snail species, down to about 1 millimetre in the smallest snails that have darts. Most darts are less than 5 millimetres long, but they are substantial compared with the size of the animal. There is the cross section of the love dart; the morphology of the dart is species-specific. For example, individual snails of the two rather similar helicid species Cepaea hortensis and Cepaea nemoralis can sometimes only be distinguished by examining the shape of the love dart and the vaginal mucus glands Note: The taxonomic placement of all the families mentioned in this article
Mollusca is the second largest phylum of invertebrate animals. The members are known as mollusks. Around 85,000 extant species of molluscs are recognized; the number of fossil species is estimated between 100,000 additional species. Molluscs are the largest marine phylum, comprising about 23% of all the named marine organisms. Numerous molluscs live in freshwater and terrestrial habitats, they are diverse, not just in size and in anatomical structure, but in behaviour and in habitat. The phylum is divided into 8 or 9 taxonomic classes, of which two are extinct. Cephalopod molluscs, such as squid and octopus, are among the most neurologically advanced of all invertebrates—and either the giant squid or the colossal squid is the largest known invertebrate species; the gastropods are by far the most numerous molluscs and account for 80% of the total classified species. The three most universal features defining modern molluscs are a mantle with a significant cavity used for breathing and excretion, the presence of a radula, the structure of the nervous system.
Other than these common elements, molluscs express great morphological diversity, so many textbooks base their descriptions on a "hypothetical ancestral mollusc". This has a single, "limpet-like" shell on top, made of proteins and chitin reinforced with calcium carbonate, is secreted by a mantle covering the whole upper surface; the underside of the animal consists of a single muscular "foot". Although molluscs are coelomates, the coelom tends to be small; the main body cavity is a hemocoel. The "generalized" mollusc's feeding system consists of a rasping "tongue", the radula, a complex digestive system in which exuded mucus and microscopic, muscle-powered "hairs" called cilia play various important roles; the generalized mollusc has three in bivalves. The brain, in species that have one, encircles the esophagus. Most molluscs have eyes, all have sensors to detect chemicals and touch; the simplest type of molluscan reproductive system relies on external fertilization, but more complex variations occur.
All produce eggs, from which may emerge trochophore larvae, more complex veliger larvae, or miniature adults. The coelomic cavity is reduced, they have kidney-like organs for excretion. Good evidence exists for the appearance of gastropods and bivalves in the Cambrian period, 541 to 485.4 million years ago. However, the evolutionary history both of molluscs' emergence from the ancestral Lophotrochozoa and of their diversification into the well-known living and fossil forms are still subjects of vigorous debate among scientists. Molluscs still are an important food source for anatomically modern humans. There is a risk of food poisoning from toxins which can accumulate in certain molluscs under specific conditions and because of this, many countries have regulations to reduce this risk. Molluscs have, for centuries been the source of important luxury goods, notably pearls, mother of pearl, Tyrian purple dye, sea silk, their shells have been used as money in some preindustrial societies. Mollusc species can represent hazards or pests for human activities.
The bite of the blue-ringed octopus is fatal, that of Octopus apollyon causes inflammation that can last for over a month. Stings from a few species of large tropical cone shells can kill, but their sophisticated, though produced, venoms have become important tools in neurological research. Schistosomiasis is transmitted to humans via water snail hosts, affects about 200 million people. Snails and slugs can be serious agricultural pests, accidental or deliberate introduction of some snail species into new environments has damaged some ecosystems; the words mollusc and mollusk are both derived from the French mollusque, which originated from the Latin molluscus, from mollis, soft. Molluscus was itself an adaptation of Aristotle's τὰ μαλάκια ta malákia, which he applied inter alia to cuttlefish; the scientific study of molluscs is accordingly called malacology. The name Molluscoida was used to denote a division of the animal kingdom containing the brachiopods and tunicates, the members of the three groups having been supposed to somewhat resemble the molluscs.
As it is now known these groups have no relation to molluscs, little to one another, the name Molluscoida has been abandoned. The most universal features of the body structure of molluscs are a mantle with a significant cavity used for breathing and excretion, the organization of the nervous system. Many have a calcareous shell. Molluscs have developed such a varied range of body structures, it is difficult to find synapomorphies to apply to all modern groups; the most general characteristic of molluscs is they are bilaterally symmetrical. The following are present in all modern molluscs: The dorsal part of the body wall is a mantle which secretes calcareous spicules, plates or shells, it overlaps the body with enough spare room to form a mantle cavity. The anus and genitals open into the mantle cavity. There are two pairs of main nerve cords. Other characteristics that appear in textbooks have significant exceptions: Estimates of accepted described living species of molluscs vary from 50,000 to a maximum of 120,000 species.
In 1969 David Nicol estimated the probable total number of living mollusc species at 107,000 of which were ab
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. While these definitions may seem adequate, when looked at more they represent problematic species concepts. For example, the boundaries between related species become unclear with hybridisation, in a species complex of hundreds of similar microspecies, in a ring species. Among organisms that reproduce only asexually, the concept of a reproductive species breaks down, each clone is a microspecies. All species are given a two-part name, a "binomial"; the first part of a binomial is the genus.
The second part is called the specific epithet. For example, Boa constrictor is one of four species of the genus Boa. None of these is satisfactory definitions, but scientists and conservationists need a species definition which allows them to work, regardless of the theoretical difficulties. If species were fixed and distinct from one another, there would be no problem, but evolutionary processes cause species to change continually, to grade into one another. Species were seen from the time of Aristotle until the 18th century as fixed kinds that could be arranged in a hierarchy, the great chain of being. In the 19th century, biologists grasped. Charles Darwin's 1859 book The Origin of Species explained how species could arise by natural selection; that understanding was extended in the 20th century through genetics and population ecology. Genetic variability arises from mutations and recombination, while organisms themselves are mobile, leading to geographical isolation and genetic drift with varying selection pressures.
Genes can sometimes be exchanged between species by horizontal gene transfer. Viruses are a special case, driven by a balance of mutation and selection, can be treated as quasispecies. Biologists and taxonomists have made many attempts to define species, beginning from morphology and moving towards genetics. Early taxonomists such as Linnaeus had no option but to describe what they saw: this was formalised as the typological or morphological species concept. Ernst Mayr emphasised reproductive isolation, but this, like other species concepts, is hard or impossible to test. Biologists have tried to refine Mayr's definition with the recognition and cohesion concepts, among others. Many of the concepts are quite similar or overlap, so they are not easy to count: the biologist R. L. Mayden recorded about 24 concepts, the philosopher of science John Wilkins counted 26. Wilkins further grouped the species concepts into seven basic kinds of concepts: agamospecies for asexual organisms biospecies for reproductively isolated sexual organisms ecospecies based on ecological niches evolutionary species based on lineage genetic species based on gene pool morphospecies based on form or phenotype and taxonomic species, a species as determined by a taxonomist.
A typological species is a group of organisms in which individuals conform to certain fixed properties, so that pre-literate people recognise the same taxon as do modern taxonomists. The clusters of variations or phenotypes within specimens would differentiate the species; this method was used as a "classical" method of determining species, such as with Linnaeus early in evolutionary theory. However, different phenotypes are not different species. Species named in this manner are called morphospecies. In the 1970s, Robert R. Sokal, Theodore J. Crovello and Peter Sneath proposed a variation on this, a phenetic species, defined as a set of organisms with a similar phenotype to each other, but a different phenotype from other sets of organisms, it differs from the morphological species concept in including a numerical measure of distance or similarity to cluster entities based on multivariate comparisons of a reasonably large number of phenotypic traits. A mate-recognition species is a group of sexually reproducing organisms that recognize one another as potential mates.
Expanding on this to allow for post-mating isolation, a cohesion species is the most inclusive population of individuals having the potential for phenotypic cohesion through intrinsic cohesion mechanisms. A further development of the recognition concept is provided by the biosemiotic concept of species. In microbiology, genes can move even between distantly related bacteria extending to the whole bacterial domain; as a rule of thumb, microbiologists have assumed that kinds of Bacteria or Archaea with 16S ribosomal RNA gene sequences more similar than 97% to each other need to be checked by DNA-DNA hybridisation to decide if they belong to the same species or not. This concept was narrowed in 2006 to a similarity of 98.7%. DNA-DNA hybri
Euthyneura is a taxonomic clade of snails and slugs, which includes species from freshwater, marine and terrestrial gastropod mollusks in the clade Heterobranchia. Euthyneura are considered the crown group of Gastropoda, are characterised by several autapomorphies, but are named for euthyneury, they are considered to be the most diverse group of Gastropoda. Within this taxon, the Gastropoda have reached their peak in species richness and ecological diversity; this obvious evolutionary success can be attributed to several factors. Marine Opisthobranchia, e.g. have evolved several clades specialised on less used food resources such as sponges or cnidarians. A key innovation in the evolution of Pulmonata was the colonization of freshwater and terrestrial habitats. Various phylogenetic studies focused on Euthyneura: Dayrat et al. Dayrat & Tillier and Grande et al.. Morphological analyses by Dayrat and Tillier demonstrated the need to explore new datasets in order to critically analyse the phylogeny of this controversial group of gastropods.
Klussmann-Kolb et al. traced an evolutionary scenario regarding colonisation of different habitats based on phylogenetic hypothesis and they showed that traditional classification of Euthyneura needs to be reconsidered. Jörger et al. have redefined major groups within the Heterobranchia and a cladogram showing phylogenic relations of Euthyneura is as follows: Cladogram showing phylogenic relations of Euthyneura sensu Wägele et al.: Kano et al. proposed a new taxon Ringipleura and classified Ringiculoidea as sister group to Nudipleura: This article incorporates CC-BY-2.0 text from the reference