ichthyopterygium

plural ichthyopterygia

1. comparativeobsoleteanatomyfish fin.

   The various adaptations of the ichthyopterygium to locomotion have little bearing on the question of homology.

   1923, William King Gregory, Roy Waldo Miner, and Gladwyn Kingsley Noble, “The carpus of Eryops and the structure of the primitive chiropterygium”, in Bulletin of the American Museum of Natural History, volume 48, pages 279–288

   2 more examples

   As already stated, they are used more like limbs for walking than fins for swimming, but this physiological resemblance to the limbs of the higher animals is not borne out by a morphological one; the fin is an ichthyopterygium, and shows no tendency towards modification in the direction of a cheiropterygium.

   1892, “On the Anatomy and Physiology of Protopterus annectens”, in The Transactions of the Royal Irish Academy, volume 30, pages 109–230

   […]whether the tetrapod limb be derived from an ichthyopterygium like that of the shark, or an archipterygium like that of Ceratodus, or a reduced archipterygium like that of Eusthenopteron[…]

   1913, Robert Broom, “On the origin of the cheiropterygium”, in Bulletin of the American Museum of Natural History, volume 32, pages 459–464