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in taxonomy: see classificationclassification,
in biology, the systematic categorization of organisms into a coherent scheme. The original purpose of biological classification, or systematics, was to organize the vast number of known plants and animals into categories that could be named, remembered, and
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a major taxonomic category that phylogenetically unites closely related species. For example, various cat species (European wildcat, jungle cat, leopard cat) are united in the genus Felis. Various pine species (Scotch pine, Siberian pine) form the genus Pinus. The scientific name of a genus is designated by a single Latin word.

Genera may consist of many species. For example, some insect and plant genera contain hundreds or thousands of species. Some genera comprise only one or a few species.

Genera having only one species, such as Desmana or Welwitschia, are called monotypic. Genera with several species are often divided into subgenera, which unite especially closely related species. Each genus belongs to a family, but between these two taxonomic categories there are often intermediate ones. For example, tribes are grouped in subfamilies, which in turn are grouped in families.

In paleobotany there also are organ genera and formal genera.



An integer associated to a surface which measures the number of holes in the surface.
A taxonomic category that includes groups of closely related species; the principal subdivision of a family.


1. Biology any of the taxonomic groups into which a family is divided and which contains one or more species. For example, Vulpes (foxes) is a genus of the dog family (Canidae)
2. Logic a class of objects or individuals that can be divided into two or more groups or species
3. Maths a number characterizing a closed surface in topology equal to the number of handles added to a sphere to form the surface. A sphere has genus 0, a torus, genus 1, etc.
References in classic literature ?
But where one genus is subordinate to another, there is nothing to prevent their having the same differentiae: for the greater class is predicated of the lesser, so that all the differentiae of the predicate will be differentiae also of the subject.
The two professors, their tempers aggravated no doubt by their injuries, had fallen out as to whether our assailants were of the genus pterodactylus or dimorphodon, and high words had ensued.
And she is an unimpeachable Christian, I am sure; perhaps of the very tribe, genus, and species you desire to propagate.
And now I find you guilty of a most flagrant breach of courtesy in interrupting my learned discourse to call attention to a mere quadruped of the genus FELIS.
All we can say is that, one by one, Elsmere's objections may be met by considerations of the same genus, and not less equal weight, relatively to a world so obscure, in its origin and issues, as that in which we live.
With these exceptions (and with that of the perfect fertility of varieties when crossed,--a subject hereafter to be discussed), domestic races of the same species differ from each other in the same manner as, only in most cases in a lesser degree than, do closely-allied species of the same genus in a state of nature.
I also frequently observed in the lagoon near the Botanic Garden, where the water is only a little less salt than in the sea, a species of hydrophilus, very similar to a water-beetle common in the ditches of England: in the same lake the only shell belonged to a genus generally found in estuaries.
The existence of a division of the genus Planaria, which inhabits the dry land, interested me much.
A small frog, of the genus Hyla, sits on a blade of grass about an inch above the surface of the water, and sends forth a pleasing chirp: when several are together they sing in harmony on different notes.
It is remarkable that in all the different kinds of glowworms, shining elaters, and various marine animals (such as the crustacea, medusae, nereidae, a coralline of the genus Clytia, and Pyrosma), which I have observed, the light has been of a well-marked green colour.
I was much interested one day by watching a deadly contest between a Pepsis and a large spider of the genus Lycosa.
The genus, or rather family, of Epeira, is here characterized by many singular forms; some species have pointed coriaceous shells, others enlarged and spiny tibiae.