''Gymnobela agassizii'' 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). . 3 ...
.
Subspecies: ''Gymnobela agassizii mexicana''
(Dall, 1889) (synonym: ''Pleurotomella agassizii mexicana''
Dall, 1889)
Description
The length of the shell attains 47 mm, its diameter 14 mm.
The shell is large and handsomely
sculptured. It contains eight convex
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, shouldered, with about sixteen thick, rounded, oblique ribs, separated by concave interspaces. The ribs do not extend above the shoulder, leaving a rather broad flattened band, which is covered by raised revolving lines, more or less decussated by prominent growth lines and slight riblets, running down the suture. The revolving lines become stronger and more elevated below the shoulder, and cross the ribs as well as their intervals. Towards 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 ...
the ribs fade out and the revolving lines become still more prominent. The outer
lip has a wide and rather deep rounded notch below the suture. Below this, it curves strongly forward and recedes again at the siphonal canal, which is rather short, narrowed and a little excurved. The
columella is smooth, curved, and obliquely narrowed at the siphonal canal. The
aperture is subovate, sinuous and rather large. The shell is white, except the columella which is stained with orange-brown.
Distribution
''G. agassizii'' can be found in Atlantic waters, ranging from the coast of
Massachusetts south to
Tobago.
[Tunnell, John W., Jr., Felder, Darryl L., & Earle, Sylvia A., eds. ''Gulf of Mexico Origin, Waters, and Biota, Volume 1: Biodiversity.'' Texas A&M University Press, 2009. 668.]
References
External links
Verrill A. E. (1885). ''Third catalogue of mollusca recently added to the fauna of the New England Coast and the adjacent parts of the Atlantic, consisting mostly of deep sea species, with notes on others previously recorded.'' Transactions of the Connecticut Academy of Arts and Sciences, 6: 395-452, pl. 42-44*
Bouchet & Warren, Revision of the North-East Atlantic bathyal and abyssal Turridae (Mollusca, Gastropoda); The Journal of Molluscan Studies, supplement 8, December 1980
{{DEFAULTSORT:Gymnobela Agassizii
agassizii
Gastropods described in 1880