''Pleurotomella normalis'' is a species of

sea snail Sea snail is a common name for slow-moving marine gastropod molluscs, usually with visible external shells, such as whelk or abalone. They share the taxonomic class Gastropoda with slugs, which are distinguished from snails primarily by the ...

, a marine

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

mollusk in the family

Raphitomidae Raphitomidae is a family of small to medium-sized sea snails, marine gastropod mollusks in the superfamily Conoidea.Bouchet P. & Rocroi J.-P. (Ed.) (2005). "Classification and nomenclator of gastropod families". ''Malacologia'' 47(1-2). . 39 ...

Description

(Original description) The short and very stout shell contains seven

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 floral ...

s. The

body whorl The body whorl is part of the morphology of the 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. In gastropods In gastropods, the b ...

measures about eight elevenths of the whole length. The apex 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 called ...

is smooth. The remainder consists of the 3½ yellow-brown nuclear whorls, beautifully reticulated with wavy transverse lines, then changing suddenly into waxy white. The subsequent whorls show spiral threads, set in pairs which frequently blend to make one flattened spiral thread, with wider interspaces between the threads. Two or three threads next the suture are stronger and wider apart than the others, the outer one strongest, giving the whorl a turreted appearance, and rising into little knobs on the transverse ridges. These ridges are rather sharp, sixteen to eighteen in number, fading away toward 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 is ...

in most but not all specimens, flexuous with the lines of growth. The columella is straight, the edge obliquely cut off, shorter than the aperture anteriorly. There is a light deposit of callus on the body. The aperture is proportionally wide, thin-lipped and about half as long as the shell. Bulletin of the Museum of Comparative Zoology at Harvard College v 9-11 (1881-1885)

Distribution

This marine species occurs in the Yucatan Strait.

References

* de Boury, E., 1899. Révision des pleurotomes éocènes du Bassin de Paris. La Feuille des Jeunes Naturalistes 29: 117-163, sér. 3° série

External links

Holotype at MNHN, Paris
* {{DEFAULTSORT:Pleurotomella Normalis normalis Gastropods described in 1881