Menestho exarata
Encyclopedia
Menestho exarata is a species
of sea snail
, a marine
gastropod mollusk in the family
Pyramidellidae
, the pyrams and their allies.
of the protoconch
are moderately large, helicoid, one-half obliquely immersed in the first volution of the teleoconch, the periphery projecting slightly beyond the left outline of the spire
. The six whorls of teleoconch are well rounded, very slightly shouldered. They are marked by faint lines of growth and well incised spiral lines, which are not all of the same strength nor are they equally spaced. Six of these appear upon the second, and seven upon the penultimate whorl between the sutures. The periphery and the base of the body whorl
are well rounded, the latter sculptured like the space between the sutures, bearing six incised lines which are not quite as strong as those between the sutures. The aperture
is oval, effuse at the junction of the outer lip
and the columella. The posterior angle is obtuse. The outer lip is thin, but opaque,. The columella is short, curved, somewhat revolute, re-enforced by the attenuated base. The parietal wall is covered by a faint callus.
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 soiled white shell is elongate-conic. It measures 4.8 mm. The at least two 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...
of the protoconch
Protoconch
A protoconch is an embryonic or larval shell of some classes of molluscs, e.g., the initial chamber of an ammonite or the larval shell of a gastropod...
are moderately large, helicoid, one-half obliquely immersed in the first volution of the teleoconch, the periphery projecting slightly beyond the left outline of the spire
Spire (mollusc)
A spire is a descriptive term for part of the coiled shell of mollusks. The word is a convenient aid in describing shells, but it does not refer to a very precise part of shell anatomy: the spire consists of all of the whorls except for the body whorl...
. The six whorls of teleoconch are well rounded, very slightly shouldered. They are marked by faint lines of growth and well incised spiral lines, which are not all of the same strength nor are they equally spaced. Six of these appear upon the second, and seven upon the penultimate whorl between the sutures. The periphery and the base 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 well rounded, the latter sculptured like the space between the sutures, bearing six incised lines which are not quite as strong as those between the sutures. 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, effuse at the junction of 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....
and the columella. The posterior angle is obtuse. The outer lip is thin, but opaque,. The columella is short, curved, somewhat revolute, re-enforced by the attenuated base. The parietal wall is covered by a faint callus.