Tetrabranchia

plural noun

Tet·​ra·​bran·​chia

-aiŋ-

: a subclass or order of Cephalopoda including among existing forms only the genus Nautilus, differing from the remaining existing cephalopods in having four gills, four auricles to the heart, and a large chambered external shell, and including many extinct forms see ammonoidea , nautiloidea compare dibranchia

Word History

Etymology

New Latin, from tetra- + -branchia

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