Chondrostei

Ganoids with persistent notochord, cartilaginous cranium, covered by dermal bones; with naked skin or bony plates instead of scales. Teeth are small or absent; branchiostegal rays scanty or absent; caudal fin is heterocercal, and IMG:content-0867.jpg:[graphic][merged small] up the bottom of fresh waters, and Glaniostomi (Sturgeons), of which Acipenser , which has spiracles, and five rows of pointed plates along the back and sides, is typical. It has no teeth and swallows other fish, etc., whole.