''Borsonella merriami'' 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

Borsoniidae Borsoniidae is a monophyletic family of small to medium-sized sea snails, marine gastropod mollusks in the superfamily Conoidea.Bouchet, P. (2011). Borsoniidae. Accessed through: World Register of Marine Species at http://www.marinespecies.o ...

.Bouchet, P. (2015). Borsonella merriami (Arnold, 1903). In: MolluscaBase (2015). Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=849189 on 2016-02-26

Description

(Original description) The small, fusiform shell is rather thin. The apex is blunt. The 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 are somewhat angular, with about fourteen slightly oblique, prominent, rather sharp transverse ridges. These ridges are most prominent on the angle of the whorl, and become obsolete near the anterior margin and at about one-third width of the whorl from the posterior margin. A narrow sutural band occupies the upper one third of the whorl. Incremental lines are visible. The suture is deeply impressed and distinct. 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 ...

is somewhat ventricose and narrowed anteriorly, with transverse ribs sometimes obsolete. The aperture is broadly elliptical, narrowed anteriorly to a prominent sinus. The posterior sinus is small, near the suture. The thin outer lip is arcuate. The columella is smooth. Dimensions: Length. 14.2 mm.; width: 5.2 mm.; body whorl 7.6 mm.; aperture, including siphonal canal, 6 mm.; siphonal canal 1.5 mm.Arnold (1903), The Paleontology and Stratigraphy of San Pedro; Memoirs of the California Academy of Sciences, 1903, 3; p. 207
(described as ''Drillia merriami'')

Distribution

This fossil species is rare in Pliocene and lower San Pedro series of

Deadman Island Deadman Island is one of the San Juan Islands in San Juan County, Washington, USA. The uninhabited, rocky island has a land area of . It is part of the Geese Islets, a collection of rocky islands and reefs near the southwest shore of Lopez Island. ...

. The specimen figured is the type, which is from the lower San Pedro series at Deadman Island (California).

References

* Tucker, J.K. 2004 ''Catalog of recent and fossil turrids (Mollusca: Gastropoda).'' Zootaxa 682:1–1295. * McLean J.H. (1996). ''The Prosobranchia''. In: Taxonomic Atlas of the Benthic Fauna of the Santa Maria Basin and Western Santa Barbara Channel. The Mollusca Part 2 – The Gastropoda. Santa Barbara Museum of Natural History. volume 9: 1–160 {{DEFAULTSORT:Borsonella Merriami merriami Gastropods described in 1903