''Compsodrillia disticha'' 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 27 mm, its diameter 7.4 mm. (Original description) The elongate-conic shell is covered with a very pale, ashy, dehiscent periostracum, which in the type is absent on the base and

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 ...

and gives the shell a decidedly bicolored effect, the shell itself appearing white. The protoconch contains 2.5 well rounded, smooth

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 ...

s, the last half crossed by a small number of axial riblets. The first postnuclear whorl has two nodulose spiral cords. On the next whorl these split into two and three tuberculated cords, the third one almost falling into the suture, being appressed to the cord at the summit of the succeeding whorls. These remain inconspicuous on the succeeding whorls, while the other two occupying the middle portion of the shell become decidedly pronounced. The cord at the summit forms an abrupt sloping shoulder, and the space between this and the first strong spiral cord constitutes the sulcus marking the posterior channel of the shell. In addition to these spiral cords the cords themselves and the spaces that separate them are marked by strong spiral threads. This is also true of the sulcus at the summit, the base, and partly so of the columella. 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 very heavy, broad, low, rounded ribs which are about twice as wide as the spaces that separate them. These ribs are rendered nodulose by the two strong spiral cords. They are also marked, as well as the intercostal spaces, by slender lines of growth that extend over the entire surface of the shell. Of these ribs, 12 are present on all the whorls. The suture is slightly constricted. The periphery is well rounded. The base of the shell is short, marked by three strong spiral cords. The columella is moderately long, slightly curved and marked by nine strong spiral cords, between and on which slender spiral threads are present. The aperture is moderately long, channeled posteriorly and anteriorly. Unfortunately, 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 ...

is fractured in the unique type so that it is impossible accurately to describe this, and the shell is not sufficiently mature to have differentiated the heavy

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 ...

behind the aperture characteristic of the group. The inner lip constitutes the heavy callus that extends upon the parietal wall.

Distribution

''C. disticha'' can be found in Caribbean waters, ranging from the western coast of

Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, a ...

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 ...

.Tunnell, John W., Jr., Felder, Darryl L., & Earle, Sylvia A., eds. ''Gulf of Mexico Origin, Waters, and Biota, Volume 1: Biodiversity.'' Texas A&M University Press, 2009. 669.

References

External links

*
Rosenberg, G.; Moretzsohn, F.; García, E. F. (2009). Gastropoda (Mollusca) of the Gulf of Mexico, pp. 579–699 in: Felder, D.L. and D.K. Camp (eds.), Gulf of Mexico–Origins, Waters, and Biota. Texas A&M Press, College Station, Texas
{{DEFAULTSORT:Compsodrillia Disticha disticha Gastropods described in 1934