''Exomilus lutarius'' 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 shell attains 3 mm, its diameter 1.15 mm. (Original description) The small, solid shell is cylindrical and abruptly truncate above. It contains five

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, three forming 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 ...

, sloping on the shoulder, perpendicular at the side, and concave at the base. The colour of the shell is grey (? bleached). The sculpture consists of deep narrow pits are formed by the intersection of radial and spiral sculpture. The radials are strong, prominent and perpendicular. The ribs are continuous, about a dozen to a whorl, knotted at the crossing of the spirals, which number four on the upper and twelve on the lower whorl. The spiral defines the basal angle larger and more prominent. Protoconch : first whorl wound oblique to the axis of the main shell, the second overhanging the third, appearing as if the apex was wrapped in a turban. The aperture is long, narrow, fortified by a 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 usua ...

, in the anterior angle of which is excavated a deep sinus. The columella is nearly straight, overlaid by a slight callus. 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 very short and wide. Hedley, C. 1907. ''The results of deep sea investigation in the Tasman Sea. Mollusca from eighty fathoms off Narrabeen''.; Records of the Australian Museum v. 6 (1907)

Distribution

This marine species is endemic to Australia and occurs off New South Wales.

References

* Laseron, C. 1954. R''evision of the New South Wales Turridae (Mollusca)''. Australian Zoological Handbook. Sydney : Royal Zoological Society of New South Wales pp. 56, pls 1–12.

External links

* {{DEFAULTSORT:Exomilus Lutarius lutarius Gastropods described in 1907 Gastropods of Australia