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''Homaloceras'' is an extinct nautiloid cephalopod from the Middle Devonian with a strongly curved shell, included in the nautilid family Centroceratidae. ''Homaloceras'' is characterized by a smooth, exogastrically curved and laterally compressed, cyrtoconic to gyroconic, shell with the ventral margin the outer rim. The venter is narrow and concave with a groove running down the middle; the dorsum on the inner rim, rounded; the sides broadly convex and convergent. The suture is only slightly sinuous, the siphuncle tubular and near the venter. ( 1964) ''Homaloceras'', named by Whiteavus in 1891, and found in North America, in Canada, is the most primitive and one of the earliest genera assigned to the Centroceratidae. ( 1964) The Nautiloidea, in which ''Homaloceras'' is included, is a subclass of once diverse and numerous shelled cephalopods characterized by a retrochoantic siphuncle in which the septal necks point back toward the apex. ==See also== *List of nautiloids 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Homaloceras」の詳細全文を読む スポンサード リンク
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