| Rhaphischismatidae Temporal range: L Carb (Miss) |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Gastropoda |
| Superorder: | Vetigastropoda[1] |
| Superfamily: | Pleurotomarioidea |
| Family: | Rhaphischismatidae J.B.Knight]], 1956 |
Rhaphischismatidae is an extinct family of gastropods from the Lower Carboniferous (Mississippian), containing a single genus, Raphischisma, and uncluded in the superorder Vetigastropoda[2] (simply a clade in Bouchet & Rocroi, 2005), and assigned to the Pleurotomariacea.[3]
Raphischisma[3] is the only known genus. Its description is that of the family.
Rhaphycasma is characterized by a discoidal shell with a rounded periphery, depressed spire, 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.