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37-518: See text The Trochidae , common name top-snails or top-shells , are a family of various sized sea snails , marine gastropod molluscs in the subclass Vetigastropoda . This family is commonly known as the top-snails because in many species the shell resembles a toy spinning top . The family Trochidae consists of the following subfamilies: Additionally, the following genera have not yet been placed in any subfamily: The length of an adult shell varies between 5 mm and 130 mm. There

74-418: A degenerate triangle if at least one side length or angle is zero. Equivalently, it becomes a "line segment". Often, the degenerate cases are the exceptional cases where changes to the usual dimension or the cardinality of the object (or of some part of it) occur. For example, a triangle is an object of dimension two, and a degenerate triangle is contained in a line , which makes its dimension one. This

111-774: A flora of his homeland Sweden, Flora Svecica (1745), and in this, he recorded the Swedish common names, region by region, as well as the scientific names. The Swedish common names were all binomials (e.g. plant no. 84 Råg-losta and plant no. 85 Ren-losta); the vernacular binomial system thus preceded his scientific binomial system. Linnaean authority William T. Stearn said: By the introduction of his binomial system of nomenclature, Linnaeus gave plants and animals an essentially Latin nomenclature like vernacular nomenclature in style but linked to published, and hence relatively stable and verifiable, scientific concepts and thus suitable for international use. The geographic range over which

148-485: A particularly common name is used varies; some common names have a very local application, while others are virtually universal within a particular language. Some such names even apply across ranges of languages; the word for cat , for instance, is easily recognizable in most Germanic and many Romance languages . Many vernacular names, however, are restricted to a single country and colloquial names to local districts. Some languages also have more than one common name for

185-516: A single gill. Along the side of the foot are three or more pairs of sensory epipodial tentacles. The head has a short, broad rostrum. The intertentacular lobes are simple or digitated, separate or united across the front, sometimes obsolete. The jaws are developed or absent. The radula is rhipidoglossate. The rhachidian teeth are always present and well-developed. The lateral teeth generally number 5 on each side, sometimes more numerous. The marginal teeth are narrow and very numerous. This family has

222-432: A worldwide distribution in tropical, temperate and arctic waters. Members of this family are among the most common marine snails along the rocky shores of Europe. Most species in the family live either in the intertidal zone or in the shallow subtidal zone, but some live in deeper water. They are usually abundant on solid, suitable substrates, like rocky shores and reefs. Species of the family Trochidae are dioecious , and

259-417: Is 180°. Thus a degenerate convex polygon of n sides looks like a polygon with fewer sides. In the case of triangles, this definition coincides with the one that has been given above. A convex polyhedron is degenerate if either two adjacent facets are coplanar or two edges are aligned. In the case of a tetrahedron , this is equivalent to saying that all of its vertices lie in the same plane , giving it

296-434: Is also a wide variation in the shape of the shell. This goes from low auriform (ear-shaped) with a wide aperture to the long, slender conical forms of typical top shells. The shape may also be subglobose, turbinate or helicoid. Their height may vary between 3 mm and 152 mm. The shell contains only a few whorls . These have a highly variable exterior, ranging from smooth or glossy to sculptured . The internal shell

333-427: Is contained in a line segment . It has thus collinear vertices and zero area. If the three vertices are pairwise distinct, it has two 0° angles and one 180° angle. If two vertices are equal, it has one 0° angle and two undefined angles. If all three vertices are equal, all three angles are undefined. A rectangle with one pair of opposite sides of length zero degenerates to a line segment, with zero area. If both of

370-461: Is in these remarks from a book on marine fish: In scientific binomial nomenclature, names commonly are derived from classical or modern Latin or Greek or Latinised forms of vernacular words or coinages; such names generally are difficult for laymen to learn, remember, and pronounce and so, in such books as field guides, biologists commonly publish lists of coined common names. Many examples of such common names simply are attempts to translate

407-413: Is nacreous. They have a brown, entirely corneous, circular, multispiral operculum which fits the aperture snugly. The operculum is formed of numerous gradually increasing whorls with a central nucleus. The aperture may be entire, tetragonal or rounded and has no reflected lip . The peristome is generally not continuous. These shells are often brightly colored and adorned with darker bands. Species of

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444-446: Is said to be degenerate. For some classes of composite objects, the degenerate cases depend on the properties that are specifically studied. In particular, the class of objects may often be defined or characterized by systems of equations. In most scenarios, a given class of objects may be defined by several different systems of equations, and these different systems of equations may lead to different degenerate cases, while characterizing

481-401: Is similar to the case of a circle, whose dimension shrinks from two to zero as it degenerates into a point. As another example, the solution set of a system of equations that depends on parameters generally has a fixed cardinality and dimension, but cardinality and/or dimension may be different for some exceptional values, called degenerate cases. In such a degenerate case, the solution set

518-659: Is the Cape dikkop (or "gewone dikkop", not to mention the presumably much older Zulu name "umBangaqhwa"); Burhinus vermiculatus is the "water dikkop". The thick joints in question are not even, in fact, the birds' knees, but the intertarsal joints —in lay terms the ankles. Furthermore, not all species in the genus have "thick knees", so the thickness of the "knees" of some species is not of clearly descriptive significance. The family Burhinidae has members that have various common names even in English, including " stone curlews ", so

555-519: The ICZN has formal rules for biological nomenclature and convenes periodic international meetings to further that purpose. The form of scientific names for organisms, called binomial nomenclature , is superficially similar to the noun-adjective form of vernacular names or common names which were used by non-modern cultures. A collective name such as owl was made more precise by the addition of an adjective such as screech . Linnaeus himself published

592-450: The fertilization occurs externally by the release of eggs and sperm. Top snail eggs are laid individually or in gelatinous egg masses in the water. Individuals may hatch as free-swimming planktonic larvae or juvenile crawlers with a short swimming stage. This family of snails consists of herbivores , grazing with their radulae on rocky surfaces, feeding on algae and vegetable detritus , and more rarely by filter-feeding, as observed in

629-588: The Hebrew Language publish from time to time short dictionaries of common name in Hebrew for species that occur in Israel or surrounding countries e.g. for Reptilia in 1938, Osteichthyes in 2012, and Odonata in 2015. Degeneracy (mathematics) In mathematics , a degenerate case is a limiting case of a class of objects which appears to be qualitatively different from (and usually simpler than)

666-710: The SSAR switched to an online version with a searchable database. Standardized names for the amphibians and reptiles of Mexico in Spanish and English were first published in 1994, with a revised and updated list published in 2008. A set of guidelines for the creation of English names for birds was published in The Auk in 1978. It gave rise to Birds of the World: Recommended English Names and its Spanish and French companions. The Academy of

703-534: The Secretariat for the AFNC. SSA is an accredited Standards Australia (Australia's peak non-government standards development organisation) Standards Development The Entomological Society of America maintains a database of official common names of insects, and proposals for new entries must be submitted and reviewed by a formal committee before being added to the listing. Efforts to standardize English names for

740-505: The amphibians and reptiles of North America (north of Mexico) began in the mid-1950s. The dynamic nature of taxonomy necessitates periodical updates and changes in the nomenclature of both scientific and common names. The Society for the Study of Amphibians and Reptiles (SSAR) published an updated list in 1978, largely following the previous established examples, and subsequently published eight revised editions ending in 2017. More recently

777-515: The author introduced into it so many new English names, that are to be found in no dictionary, and that do not preclude the necessity of learning with what Latin names they are synonymous. A tolerable idea may be given of the danger of too great a multiplicity of vulgar names, by imagining what geography would be, or, for instance, the Post-office administration, supposing every town had a totally different name in every language. Various bodies and

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814-493: The authors of many technical and semi-technical books do not simply adapt existing common names for various organisms; they try to coin (and put into common use) comprehensive, useful, authoritative, and standardised lists of new names. The purpose typically is: Other attempts to reconcile differences between widely separated regions, traditions, and languages, by arbitrarily imposing nomenclature, often reflect narrow perspectives and have unfortunate outcomes. For example, members of

851-408: The choice of the name "thick-knees" is not easy to defend but is a clear illustration of the hazards of the facile coinage of terminology. For collective nouns for various subjects, see a list of collective nouns (e.g. a flock of sheep, pack of wolves). Some organizations have created official lists of common names, or guidelines for creating common names, hoping to standardize

888-482: The family Trochidae differ from those in the family Turbinidae in having a corneous, never calcareous, operculum, which is always multispiral. The animal is similar in general form to the Turbinidae. The top snails are characterized by some primitive traits: a heart with two atria . They have retained only one kidney and the second osphradium has been lost in the course of evolution. The mantle cavity contains

925-464: The general public (including such interested parties as fishermen, farmers, etc.) to be able to refer to one particular species of organism without needing to be able to memorise or pronounce the scientific name. Creating an "official" list of common names can also be an attempt to standardize the use of common names, which can sometimes vary a great deal between one part of a country and another, as well as between one country and another country, even where

962-522: The genus Burhinus occur in Australia, Southern Africa, Eurasia, and South America. A recent trend in field manuals and bird lists is to use the name " thick-knee " for members of the genus. This, in spite of the fact that the majority of the species occur in non-English-speaking regions and have various common names, not always English. For example, "Dikkop" is the centuries-old South African vernacular name for their two local species: Burhinus capensis

999-610: The genus Umbonium . Common name In chemistry , IUPAC defines a common name as one that, although it unambiguously defines a chemical, does not follow the current systematic naming convention, such as acetone , systematically 2-propanone , while a vernacular name describes one used in a lab, trade or industry that does not unambiguously describe a single chemical, such as copper sulfate , which may refer to either copper(I) sulfate or copper(II) sulfate. Sometimes common names are created by authorities on one particular subject, in an attempt to make it possible for members of

1036-711: The modern (now binding) International Code of Nomenclature for algae, fungi, and plants contains the following: Art. 68. Every friend of science ought to be opposed to the introduction into a modern language of names of plants that are not already there unless they are derived from a Latin botanical name that has undergone but a slight alteration. ... ought the fabrication of names termed vulgar names, totally different from Latin ones, to be proscribed. The public to whom they are addressed derives no advantage from them because they are novelties. Lindley's work, The Vegetable Kingdom, would have been better relished in England had not

1073-404: The object or in some configuration space . For example, a conic section is degenerate if and only if it has singular points (e.g., point, line, intersecting lines). A degenerate conic is a conic section (a second-degree plane curve , defined by a polynomial equation of degree two) that fails to be an irreducible curve . A degenerate triangle is a "flat" triangle in the sense that it

1110-513: The rectangle's pairs of opposite sides have length zero, the rectangle degenerates to a point. A hyperrectangle is the n -dimensional analog of a rectangle. If its sides along any of the n axes has length zero, it degenerates to a lower-dimensional hyperrectangle, all the way down to a point if the sides aligned with every axis have length zero. A convex polygon is degenerate if at least two consecutive sides coincide at least partially, or at least one side has zero length, or at least one angle

1147-418: The rest of the class; " degeneracy " is the condition of being a degenerate case. The definitions of many classes of composite or structured objects often implicitly include inequalities. For example, the angles and the side lengths of a triangle are supposed to be positive. The limiting cases, where one or several of these inequalities become equalities, are degeneracies. In the case of triangles, one has

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1184-488: The same animal. For example, in Irish, there are many terms that are considered outdated but still well-known for their somewhat humorous and poetic descriptions of animals. w/ literal translations of the poetic terms Common names are used in the writings of both professionals and laymen . Lay people sometimes object to the use of scientific names over common names, but the use of scientific names can be defended, as it

1221-576: The same language is spoken in both places. A common name intrinsically plays a part in a classification of objects, typically an incomplete and informal classification, in which some names are degenerate examples in that they are unique and lack reference to any other name, as is the case with say, ginkgo , okapi , and ratel . Folk taxonomy , which is a classification of objects using common names, has no formal rules and need not be consistent or logical in its assignment of names, so that say, not all flies are called flies (for example Braulidae ,

1258-560: The same non-degenerate cases. This may be the reason for which there is no general definition of degeneracy, despite the fact that the concept is widely used and defined (if needed) in each specific situation. A degenerate case thus has special features which makes it non-generic , or a special case . However, not all non-generic or special cases are degenerate. For example, right triangles , isosceles triangles and equilateral triangles are non-generic and non-degenerate. In fact, degenerate cases often correspond to singularities , either in

1295-402: The scientific name into English or some other vernacular. Such translation may be confusing in itself, or confusingly inaccurate, for example, gratiosus does not mean "gracile" and gracilis does not mean "graceful". The practice of coining common names has long been discouraged; de Candolle's Laws of Botanical Nomenclature , 1868, the non-binding recommendations that form the basis of

1332-407: The so-called "bee lice") and not every animal called a fly is indeed a fly (such as dragonflies and mayflies ). In contrast, scientific or biological nomenclature is a global system that attempts to denote particular organisms or taxa uniquely and definitively , on the assumption that such organisms or taxa are well-defined and generally also have well-defined interrelationships; accordingly

1369-832: The use of common names. For example, the Australian Fish Names List or AFNS was compiled through a process involving work by taxonomic and seafood industry experts, drafted using the CAAB (Codes for Australian Aquatic Biota) taxon management system of the CSIRO , and including input through public and industry consultations by the Australian Fish Names Committee (AFNC). The AFNS has been an official Australian Standard since July 2007 and has existed in draft form (The Australian Fish Names List) since 2001. Seafood Services Australia (SSA) serve as

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