acentrous

Adjective

 * 1)  lacking vertebral centra
 * 2) * 2001, "Axial Skeleton", David Cannatella,
 * "Some bony fishes (Teleostei,, , and Brachiopterygii) have well-ossified centra and neural and hemal arches. Others (Dipnoi, , and ) lack centra (acentrous), and the notochord is unconstricted, and the bony neural and hemal arches simply rest on it."