Permoceras has a smooth, compressed, involute shell; whorls higher than wide; earlier whorls hidden from view. The venter is rounded as are the ventral and umbilical shoulders; the flanks flattened. The
siphuncle is ventrally subcentral. The suture, which is most characteristic, has a deep, narrow pointed ventral lobe and large, asymmetrical pointed lobes on either side. The coiling and whorl structure of
Permoceras almost precisely resembles those of
Pseudonautilus from the Upper Jurassic. ==Taxonomy==