Rhaphischismatidae
Encyclopedia
Rhaphischismatidae is an extinct family
of gastropods from the Lower Carboniferous (Mississippian), containing a single genus, Raphischisma, and uncluded in the superorder Vetigastropoda
(simply a clade in Bouchet & Rocroi, 2005
), and assigned to the Pleurotomariacea
.
, umbilical callus formed by the inward extension of the lower aperture lip, and a deep, narrow slit, that extends along the upper surface, near the upper suture. The unique features of the lower lip
generate an umbilical callus and deep, long, exhalent slit on the upper side along with the generally smooth form. They set this genus, and family, apart from other Pleuromomaracean gastropods.
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...
of gastropods from the Lower Carboniferous (Mississippian), containing a single genus, Raphischisma, and uncluded in the superorder Vetigastropoda
Vetigastropoda
Vetigastropoda is a major taxonomic group of sea snails, marine gastropod mollusks that form a very ancient lineage. Taxonomically Vetigastropoda are sometimes treated as an order although they are a clade in Bouchet and Rocroi, 2005....
(simply a clade in Bouchet & Rocroi, 2005
Taxonomy of the Gastropoda (Bouchet & Rocroi, 2005)
The taxonomy of the Gastropoda as it was revised by Philippe Bouchet and Jean-Pierre Rocroi is currently the most up-to-date overall system for classifying gastropod mollusks...
), and assigned to the Pleurotomariacea
Pleurotomariacea
The superfamily Pleurotomariacea, based on Swainson, 1840 and described in the Treatise on Invertebrate Paleontology, was established for mostly conispiral, but also discoidal and auriform shells that have a nacreous, aragonite, inner layer.The Pleurotomariacea, now often seen as...
.
Description
Rhaphycasma is characterized by a discoidal shell with a rounded periphery, depressed spireSpire (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...
, umbilical callus formed by the inward extension of the lower aperture lip, and a deep, narrow slit, that extends along the upper surface, near the upper suture. The unique features of the lower 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....
generate an umbilical callus and deep, long, exhalent slit on the upper side along with the generally smooth form. They set this genus, and family, apart from other Pleuromomaracean gastropods.