''Mangelia subcircularis'' 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 Mangeliidae.

Description

The length of the shell attains 8 mm, its diameter 2.7 mm. (Original description) The small, slender, thin shell has a blunt apex. It is whitish and glistening. It shows a swollen

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 ...

of 1½

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 ...

and 4½ subsequent well rounded whorls. The suture is distinct, appressed, with a smooth, hardly constricted fasciole in front of it. The axial sculpture consists chiefly of rather strong flexuous incremental lines and a few gradually obsolescent riblets on the earlier whorls. The spiral sculpture consists of (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 ...

18–20) fine prominent threads rising above the incremental lines, with wider interspaces, covering the whole whorl in front of the fasciole;. The aperture is ovate, measuring about⅓ the whole length. 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 ...

forms nearly a semicircle. The outer lip is thin and arcuate. 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 ...

is wide. The columella is twisted, attenuated in front; axis impervious. Dall W. H. (1927). Small shells from dredgings off the southeast coast of the United States by the United States Fisheries Steamer "Albatross", in 1885 and 1886; Proceedings of the United States National Museum, 70(18): 1–134

Distribution

This marine species was found off Georgia, USA.

References

External links

Smithsonian Institution: ''Mangilia subcircularis''
* {{DEFAULTSORT:Mangelia Subcircularis subcircularis Gastropods described in 1927