''Pleurotomella dinora'' 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

The length of the (decollated) shell attains 15 mm, its diameter 7 mm. (Original description) The small shell is short-fusiform and stout. It is white with a pale yellowish periostracum. It contains about 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 apex is defective. The subsequent whorls are rather rapidly increasing, with an appressed suture behind a smooth and constricted anal fasciole. In front of which the shell is shouldered by a series of short, slightly protective ribs, of which, on the penultimate whorl there are fifteen, with subequal interspaces and crossed by half a dozen irregularly spaced spiral striations. These striae are ill-defined, and on 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 ...

extend over the base of the shell to 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 ...

. On the last half of the body whorl the ribs become obsolete The aperture is narrow. The

anal sulcus The anal sulcus, also called the anal sinus or anal canal, in Gastropods is a notch, a shelly tube at the top of the aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and fo ...

at the suture is wide and deep. The outer lip in front of it is prominently arcuate, thin and simple. The columellar lip is smooth with a thin wash of callus. The columella is twisted and rapidly attenuated. The axis is impervious. The siphonal canal is moderately wide, short and slightly recurved. W.H. Dall (1908) Reports on the Mollusca and Brachiopoda, Bulletin of the Museum of Comparative Zoology at Harvard College. vol. 43

Description

Distribution

References

External links