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''Octamerella'' is an extinct genus of prehistoric nautiloid from the oncocerid family Hemiphragmoceratidae that lived in what is now Europe and North America during the Middle Silurian. ''Octamerella'' has a breviconic shell and a mature aperture that is contracted so as to have four pairs of dorsolateral sinusus, four on each side, and a narrow mid dorsal salient. The two ventral-most sinus pairs are typically the larges while the dorsal-most pair is short and wide, forming a circular opening. (Sweet, 1964) ==References== * Sweet, W.C. 1964.Nautilodea-Oncocerida; Treatise on Invertebrate Paleontology, Part K; Geol Soc of America and Univ Kansas Press, Teichert & Moore eds. * Sepkoski, J.J. Jr. 2002. A compendium of fossil marine animal genera. D.J. Jablonski & M.L. Foote (eds.). ''Bulletins of American Paleontology'' 363: 1–560. (Sepkoski's Online Genus Database (CEPHALOPODA) ) * () 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「Octamerella」の詳細全文を読む スポンサード リンク
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