ganoidei

from The Century Dictionary.

• In Agassiz's system of classification, one of four orders into which the class of fishes was divided.
• Hence In Müller's system, a subclass of fishes with muscular or multivalvular aortic bulb, free branchiæ, covered gill-cavity, and no optic chiasm, a spiral intestinal valve (sometimes rudimentary), and usually fulcra on one or more fins.

from the GNU version of the Collaborative International Dictionary of English.

• noun plural (Zoöl.) One of the subclasses of fishes. They have an arterial cone and bulb, spiral intestinal valve, and the optic nerves united by a chiasma. Many of the species are covered with bony plates, or with ganoid scales; others have cycloid scales.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a group of mostly extinct primitive bony fishes characterized by armor-like bony scales