''Spirotropis lithocolleta'' 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 ...

Drilliidae The Drilliidae are a taxonomic family of small predatory sea snails with high-spired shells. They are classified as marine gastropod mollusks in the superfamily Conoidea. This family has no subfamilies. It consists of about 30 genera and approxi ...

Description

The size of an adult shell varies between 10 mm and 16.5 mm. (Original description) The high, narrow, conical shell has a short base and a blunt

apex The apex is the highest point of something. The word may also refer to: Arts and media Fictional entities * Apex (comics), a teenaged super villainess in the Marvel Universe * Ape-X, a super-intelligent ape in the Squadron Supreme universe *Apex, ...

. It is bluntly angulated and tubercled, thin, smooth, ivory-white. There is no longitudinal

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 ...

but very fine scratch-like lines of growth. Behind and parallel to the lip-edge there are three narrow sickle-shaped ribs, which are probably an accidental feature. Very slightly above the middle of the

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 runs a feeble angulation set with round but a little narrowed and obliquely elongated knobs, of which there are about 12 on each whorl. On the first regular whorl there are about 10. Before the end of the penultimate they have quite died out, and even the angulation of the whorl tends to disappear. There are faint traces of microscopic spirals over the whole shell, rather in the texture than on the surface. These are rather more distinct below the suture. And in the sinus-area there are two faint impressed lines. The colour of the shell is polished ivory-white. The conical

spire A spire is a tall, slender, pointed structure on top of a roof of a building or tower, especially at the summit of church steeples. A spire may have a square, circular, or polygonal plan, with a roughly conical or pyramidal shape. Spires are ...

is high and narrow. The 2½ embryonic whorls 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 ...

are cylindrical, quite smooth, and have the extreme point very much flattened down on one side so as to make a perfectly rounded tip. The shell contains 11½ whorls in all. They are rather short, and of very regular increase, slightly convex, but not contracted either above or below. The body whorl is very slightly tumid with a rounded base, contracting very rapidly to a short broad snout, which is abruptly truncated at the point. The suture is rather oblique, fine, regular, defined by a slight impression: it rises a very little at the aperture. The

aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. An ...

is pear-shaped, small, narrow and a little contracted in front. 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 somewhat thickened, with a small reverted edge in the sinus and at the point of the

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 ...

, but sharp and a little contracted in all the rest of its extent. It leaves the body at a slightly acute angle, and retreats at once obliquely, but very shortly, to form the narrow rounded sinus, from which, almost parallel to the line of the suture (i.e., with a very slight oblique direction forwards), it sweeps far out in a great convex-edged wing, retreating again a little to the edge of the very short siphonal canal, where it turns slightly and obliquely forwards. The point of the siphonal canal is open, and cut off obliquely from the right forwards to the point of the pillar. The inner lip has a thin porcellanous glaze, a little thickened at the top. It spreads narrowly on the body, which is a good deal excavated. 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 straight, short, conical, very little truncated, with a slightly twisted and sharpish edge, and a pretty solid though fine point at the extreme front of the shell.Watson, R.B. (1886) Report on the Scaphopoda and Gasteropoda collected by the H. M. S. Challenger during the years 1873–76. Report on the Scientific Results of the Voyage of the ‘Challenger’ (Zoology), 15, 1–756, 50 pls
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Distribution

This species occurs in the

demersal zone The demersal zone is the part of the sea or ocean (or deep lake) consisting of the part of the water column near to (and significantly affected by) the seabed and the benthos. The demersal zone is just above the benthic zone and forms a laye ...

of the Caribbean Sea ( St. Thomas) and the Atlantic Ocean off

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

References

* R.B. Watson, ''Preliminary Report, pt. 9'', Journ. Linn. Soc. Lond., voL xv.p. 441.
Tucker, J.K. 2004 ''Catalog of recent and fossil turrids (Mollusca: Gastropoda)''. Zootaxa 682:1–1295

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. Biodiversity. Texas A&M Press, College Station, Texas
{{Taxonbar, from=Q7578218 lithocolleta Gastropods described in 1881