Chondrichthyes, or cartilaginous fishes, are jawed fish with paired fins, paired nares, scales, two-chambered hearts, and skeletons made of cartilage rather than bone. They are divided into two subclasses: Elasmobranchii (sharks, rays and skates) and Holocephali (chimaera, sometimes called ghost sharks, which are sometimes separated into their own class). Image:Acanthodii.jpg This prehistoric fish-related article is a stub. You can help Fossil Wiki by [ expanding it].