''Leucosyrinx plebeia'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

sea snail Sea snails are slow-moving marine (ocean), marine gastropod Mollusca, molluscs, usually with visible external shells, such as whelk or abalone. They share the Taxonomic classification, taxonomic class Gastropoda with slugs, which are distinguishe ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Pseudomelatomidae Pseudomelatomidae is a family (biology), family of predatory sea snails, marine gastropods included in the superfamily Conoidea (previously Conacea) and part of the Neogastropoda (Taxonomy of the Gastropoda (Bouchet & Rocroi, 2005), Bouchet & Ro ...

Description

The length of the shell varies between 16 mm and 38 mm. (Original description) The shell is high, narrow, fusiform, subscalar, angulated and tubercled on the angle, strong, rough, yellowish white. Sculpture : Longitudinals—the upper

whorl A whorl ( or ) is an individual circle, oval, volution or equivalent in a whorled pattern, which consists of a spiral or multiple concentric objects (including circles, ovals and arcs). In nature File:Photograph and axial plane floral diagra ...

s are nearly bisected by a bluntisb angulation, which is made more marked by about 20 small, oblique, longitudinally elongated knobs, of which scarcely a trace appears below or above the keel. They become fewer up the spire and die out on the

body whorl The body whorl is part of the morphology (biology), morphology of the gastropod shell, shell in those gastropod mollusks that possess a coiled shell. The term is also sometimes used in a similar way to describe the shell of a cephalopod mollusk ...

. There are very many, rough, very unequal, curved lines of growth. The whole surface is covered by coarse, unequal, and very irregular threads, varying in their direction, and interrupted by the longitudinal lines of growth. These are most equal in the infra-sutural tract, where the line of the old sinus-markings lie. Below the keel they occur alternatingly as stronger and finer. On the base and

aperture In optics, the aperture of an optical system (including a system consisting of a single lens) is the hole or opening that primarily limits light propagated through the system. More specifically, the entrance pupil as the front side image o ...

they are coarse, but almost disappear on the point. They and the suture are exceptionally independent of one another. The colour of the shell is yellowish porcellanous white. The spire is high, narrow, conical, and slopingly subscalar. The

apex The apex is the highest point of something. The word may also refer to: Arts and media Fictional entities * Apex (comics) A-Bomb Abomination Absorbing Man Abraxas Abyss Abyss is the name of two characters appearing in Ameri ...

is broken. The shell contains probably 9-10 whorls, rather narrow, somewhat hollowed on the shoulder below the suture. Below the keel their profile-line is straight, but contracted to the suture below. The base (whose upper limit is defined by a very slight angulation) is conical, drawn out pretty much in the axial line into a long, narrowish, cylindrical, strong, and slightly reverted aperture. The suture is a rather minute, sharp, somewhat irregular line, which does not at all follow the spiral markings, but crosses these up and down in an unusually irregular manner. It is well defined by the concave hollow formed by the contraction of the whorls above and below it. The aperture is club-shaped, being somewhat angularly ovate above (with a sharpish point at the top and an angulation at the keel), and prolonged below into the somewhat oblique open

siphonal canal The siphonal canal is an anatomical feature of the shells of certain groups of sea snails within the clade Neogastropoda. Some sea marine gastropods have a soft tubular anterior extension of the mantle called a siphon through which water i ...

, which is kept open by the oblique cutting away of the

columella Lucius Junius Moderatus Columella (, Arabic: ) was a prominent Roman writer on agriculture in the Roman Empire. His in twelve volumes has been completely preserved and forms an important source on Roman agriculture and ancient Roman cuisin ...

. The outer

lip The lips are a horizontal pair of soft appendages attached to the jaws and are the most visible part of the mouth of many animals, including humans. Mammal lips are soft, movable and serve to facilitate the ingestion of food (e.g. sucklin ...

is sharp, but strong. It leaves the body at an acute angle and retreats towards the right to form the sinus, which is open and near but not immediately at the body: from the sinus the lip-edge advances with a strong forward convexity to the point of the siphonal canal. Laterally it is also rather convex, but is contracted into the aperture, along the edge of which it is pretty straight with a somewhat oblique direction towards the left, and here it is patulous. The inner lip is porcellanous, smooth, narrow, cut off, and slightly twisted in front, and running out at the point to a sharp edge along the siphonal canal, the point of which is then rounded and patulous. Report on the scientific results of the voyage of H.M.S. Challenger during the years 1873-76 under the command of Captain George S. Nares ... and the late Captain Frank Tourle Thomson, R.N.; Zoology vol. 15 (1886)

Distribution

This species occurs in the

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

off Northeast

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

References

{{DEFAULTSORT:Leucosyrinx Plebeia plebeia Gastropods described in 1881