''Compsodrillia nana'' is a

species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...

of sea snail, a marine gastropod

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is es ...

in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Pseudomelatomidae Pseudomelatomidae is a family of predatory sea snails, marine gastropods included in the superfamily Conoidea (previously Conacea) and part of the Neogastropoda ( Bouchet & Rocroi, 2005). In 1995 Kantor elevated the subfamily Pseudomelatominae ...

Description

The length of the shell attains 8.7 mm, its diameter 3.1 mm. (Original description) The small, elongate-conic shell is yellowish white. The first one-half of the

protoconch A protoconch (meaning first or earliest or original shell) is an embryonic or larval shell which occurs in some classes of molluscs, e.g., the initial chamber of an ammonite or the larval shell of a gastropod. In older texts it is also calle ...

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). Whorls in nature File:Photograph and axial plane flo ...

is well rounded, smooth, the last half is marked by a few rather distantly spaced, slightly protractively slanting axial riblets. The postnuclear are whorls well rounded, the first marked by three slender spiral cords, of which the anterior two increase more rapidly in size than the first one, which remains rather feeble. The summit of the whorls is marked by a smooth spiral cord representing the portion appressed to the preceding turn. On the later whorls the sinal sulcus at the summit is crossed by two slender spiral threads anterior to the cord at the summit which divides the space between this cord and the first strong nodulose cord into nearly equal portions. There is also a slender spiral cord between the first and second strong nodulose cords on the antepenultimate turn and two on the body whorl. There are two slender spiral cords between the second nodulose cord and the nodulose cord at the periphery which shows weakly in the suture of the whorls. The axial

sculpture Sculpture is the branch of the visual arts that operates in three dimensions. Sculpture is the three-dimensional art work which is physically presented in the dimensions of height, width and depth. It is one of the plastic arts. Durable sc ...

consists of strong, broad, rounded, protractively slanting ribs, which are about twice as wide as the spaces that separate them. The junction of these ribs with the stronger spiral cords produces nodules. The suture is well impressed. The periphery is marked by a nodulose spiral cord, the major portion of which, however, falls immediately below the periphery. The base of the shell is short, well rounded, marked by two nodulose spiral cords. The

columella Lucius Junius Moderatus Columella (; Arabic: , 4 – ) was a prominent writer on agriculture in the Roman Empire. His ' in twelve volumes has been completely preserved and forms an important source on Roman agriculture, together with the ...

is rather short and stumpy, marked by nine subequal, closely spaced, feebly nodulose spiral cords. The aperture is rather short, decidedly channeled anteriorly and posteriorly, the posterior channel falling in the posterior angle of the aperture. There is a strong

varix A varix (pl. varices) is an abnormally dilated vessel with a tortuous course. Varices usually occur in the venous system, but may also occur in arterial or lymphatic vessels. Examples of varices include: * Varicose veins, large tortuous veins ...

a little behind the edge of the outer

lip The lips are the visible body part at the mouth of many animals, including humans. Lips are soft, movable, and serve as the opening for food intake and in the articulation of sound and speech. Human lips are a tactile sensory organ, and can be ...

, and the outer lip between the channel at the summit and its base is protracted into a clawlike element, which, however, does not infringe upon the aperture. The inner lip is reflected as a distinct wall upon the columella and forms a heavy callus on the parietal wall.Bartsch, P. (1934) Reports on the collections obtained by the first Johnson-Smithsonian deep-sea expedition to the Puerto Rican deep; new mollusks of the family Turritidae. Smithsonian Miscellaneous Collections, 91, 1–29, 8 pls
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Distribution

This species occurs in the Caribbean Sea off

Puerto Rico Puerto Rico (; abbreviated PR; tnq, Boriken, ''Borinquen''), officially the Commonwealth of Puerto Rico ( es, link=yes, Estado Libre Asociado de Puerto Rico, lit=Free Associated State of Puerto Rico), is a Caribbean island and Unincorporated ...

References

External links

* * {{DEFAULTSORT:Compsodrillia Nana

nana Nana, Nanna, Na Na or NANA may refer to: People and fictional characters * Nana (given name), including a list of people and characters with the given name * Nana (surname), including a list of people and characters with the surname * Nana ( ...

Gastropods described in 1934