Odostomia eugena
Encyclopedia
Odostomia eugena is a species
of sea snail
, a marine
gastropod mollusk in the family
Pyramidellidae
, the pyrams and their allies.
number at least two, and are small, smooth, and obliquely half immersed in the first of the succeeding turns. The seven and one-half post-nuclear whorls are well rounded, moderately contracted
at the suture, and well shouldered at the summit. They are marked by strong, very retractive axial ribs, of which 14 occur upon the first, 16 upon the second, 18 upon the third to fifth, and 22 upon the penultimate whorl. In addition to these ribs the whorls are marked by four strong spiral cords between the sutures which render their junction with the ribs tuberculate. The spaces enclosed by the ribs and cords form oval pits, the long axis of which coincides with the spiral sculpture. The sutures are channeled. The periphery of the body whorl
are marked by a moderately broad groove, which is crossed by the continuation of the axial ribs which terminate at the posterior edge of the first basal keel. The base of the body whorl is well rounded, marked by six spiral keels which grow successively weaker from the periphery to the umbilical region. The broad spaces between these keels are crossed by slender, raised axial threads. The aperture
is oval. The posterior angle is obtuse. The outer lip
is
thin, showing the external sculpture within. The columella is stout, curved, strongly reflected and re-enforced by the base, provided with a strong fold at its insertion.
to Hipolito Point, California.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of sea snail
Sea snail
Sea snail is a common name for those snails that normally live in saltwater, marine gastropod molluscs....
, a marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
gastropod mollusk in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Pyramidellidae
Pyramidellidae
Pyramidellidae, common name the pyram family, or pyramid shells, is a voluminous taxonomic family of mostly small and minute ectoparasitic sea snails, marine heterobranch gastropod molluscs or micromolluscs....
, the pyrams and their allies.
Description
The elongate-conic shell is milk-white. It measures 4.3 mm. The nuclear whorlsWhorl (mollusc)
A whorl is a single, complete 360° revolution or turn in the spiral growth of a mollusc shell. A spiral configuration of the shell is found in of numerous gastropods, but it is also found in shelled cephalopods including Nautilus, Spirula and the large extinct subclass of cephalopods known as the...
number at least two, and are small, smooth, and obliquely half immersed in the first of the succeeding turns. The seven and one-half post-nuclear whorls are well rounded, moderately contracted
at the suture, and well shouldered at the summit. They are marked by strong, very retractive axial ribs, of which 14 occur upon the first, 16 upon the second, 18 upon the third to fifth, and 22 upon the penultimate whorl. In addition to these ribs the whorls are marked by four strong spiral cords between the sutures which render their junction with the ribs tuberculate. The spaces enclosed by the ribs and cords form oval pits, the long axis of which coincides with the spiral sculpture. The sutures are channeled. The periphery of the body whorl
Body whorl
Body whorl is part of the morphology of a coiled gastropod mollusk.- In gastropods :In gastropods, the body whorl, or last whorl, is the most recently-formed and largest whorl of a spiral or helical shell, terminating in the aperture...
are marked by a moderately broad groove, which is crossed by the continuation of the axial ribs which terminate at the posterior edge of the first basal keel. The base of the body whorl is well rounded, marked by six spiral keels which grow successively weaker from the periphery to the umbilical region. The broad spaces between these keels are crossed by slender, raised axial threads. The aperture
Aperture (mollusc)
The aperture is an opening in certain kinds of mollusc shells: it is the main opening of the shell, where part of the body of the animal emerges for locomotion, feeding, etc....
is oval. The posterior angle is obtuse. The outer lip
Lip (gastropod)
In the shell of a gastropod mollusk , the margin of the aperture is called the lip or the peristome. In other words, this is a term used to describe part of gastropod shell anatomy....
is
thin, showing the external sculpture within. The columella is stout, curved, strongly reflected and re-enforced by the base, provided with a strong fold at its insertion.
Distribution
This species occurs in the Pacific Ocean off San PedroSan Pedro Bay (California)
San Pedro Bay is an inlet on the Pacific Ocean coast of southern California, United States. It is the site of the Port of Los Angeles and the Port of Long Beach, which together form the fifth-busiest port facility in the world and easily the busiest in the Western Hemisphere...
to Hipolito Point, California.