Archipterygium

‖Ar‐chip′te‐ryg″i‐um (är‐kĭp′tē̍‐rĭj″ĭ‐ŭm), n. [NL., fr. Gr. pref. αρχἰ- (E. arch-) + πτερύγιον wing, fin.] (Anat.) The primitive form of fin, like that of Ceratodus.