''Tenaturris janira'' 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 11 mm, its diameter 4.5 mm. (Original description) The small shell is brownish, with an acute brown

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 4½ regularly increasing

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 (apparently smooth but slightly eroded), changed abruptly into the sculpture of the five subsequent whorls. The axial 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 ...

10) low rounded ribs with wider interspaces, obsolete on the base and incremental sculpture indicated by the rather distant sharp striae. The spiral sculpture consists of (on the spire two, on the body whorl three) rather prominent nodules on the ribs with no conspicuous cord in the corresponding part of the interspaces. Otherwise the spiral sculpture, especially on the latter whorls, comprises sharp narrow grooves with wider flattened interspaces which become more cordlike on the earlier whorls and the base. The whorls are moderately rounded with no indication of an anal fasciole. The suture is distinct but not appressed. The aperture in the type specimen is elongate ovate with a simple columella and a thin sharp outer lip. 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 short, deep and forms a distinct but small siphonal fasciole, and is and slightly recurved. Dall, William Healey. Summary of the marine shellbearing mollusks of the northwest coast of America: from San Diego, California, to the Polar Sea, mostly contained in the collection of the United States National Museum, with illustrations of hitherto unfigured species. No. 112. Govt. print. off., 1921

Distribution

This marine species was found off Lower California.

Description

Distribution

References

Further reading