Chondrichthyes (; from Greek χονδρ-
chondr- 'cartilage', ἰχθύς
ichthys 'fish') is a
class that contains the
cartilaginous fishes: they are jawed
vertebrates with paired fins, paired
nares, scales, a heart with its chambers in series, and skeletons made of
cartilage rather than
bone. The class is divided into two subclasses:
Elasmobranchii (
sharks,
rays,
skates, and
sawfish) and
Holocephali (
chimaeras, sometimes called ghost sharks, which are sometimes separated into their own class).