Wikipedia
Euomphalus
Euomphalus is a genus of fossil marine gastropods known to have lived from the Silurian to the Middle Permian.
Euomphalus is characterized by a closely coiled shell with a depressed to slightly elevated spire and a channel-bearing angulation (a selenizone) on the upper surface of the whorls. The lower surface of the whorls is rounded to angular.
Amphiscapha, Philoxene, and Straparollus are among similar related genera. Serpulospira, also related, differs in having a broadly open spiral in the adult form.