Cycloceras

Cycloceras is an extinct nautiloid cephalopod genus from the Carboniferous of Western Europe, (Ireland and Scotland) of unknown affinity with the Orthocerida.^[1]

Cycloceras Temporal range: Ordovician-Permian
Cranoceras depressum
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Order:	†Orthocerida
Genus:	†Cycloceras M'Coy, 1844

Taxonomy

Cycloceras was named by McCoy (1844 and assigned to the Michelinoceratida by Flower (1962)and to the Orthocerida by Sweet in Teichert et al. (1964);^[2] Cycloceras is possibly a member of the Cycloceratidae and may be synonymous with Perigrammoceras.^{[citation needed]}

Morphology

The type species of Cycloceras, C. annularis, is based in an internal mold of a body chamber on which the position of the siphuncle is indiscernible (Sweet 1964,) Species referred to Cycloceras are annulated, subcylindrical orthocones with no longitudinal ornamentation . Fig 186, p K258 Teichert et al. (1964) shows Cycloceras as narrow, gently expanding, annulated orthocone with a narrow subcentral siphuncle. Annuli (circular transverse bands or costae) are thick and close spaced, giving a corrugated appearance.