metapterygium
/ˌmɛtəptəˈrɪdʒɪəm/Ichthyol.
noun
The prominent posterior cartilage at the base of the pectoral (and sometimes pelvic) fin in certain cartilaginous fishes.
Origin
Late 19th century; earliest use found in American Naturalist. From German Metapterygium (C. Gegenbaur Grundzüge der Vergleichenden Anatomie (ed. 2) 684) from meta- + ancient Greek πτερύγιον.