plural noun
Tet·​ra·​bran·​chia | \ -aiŋ- \

Definition of Tetrabranchia

: 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

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History and Etymology for Tetrabranchia

New Latin, from tetra- + -branchia

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Cite this Entry

“Tetrabranchia.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/Tetrabranchia. Accessed 2 Dec. 2020.

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