A kind of fish scale, characteristic of primitive bony fishes (Osteichthyes) such as sturgeons. Similar to cosmoid scales but with a much thicker layer of ganoine. They grow by the addition of material all round (as opposed to cosmoid scales, which grow only by adding material to the inner layer).

Ga"noid (?), a. [Gr. brightness + -oid.] Zool.

Of or pertaining to Ganoidei. -- n. One of the Ganoidei.

Ganoid scale Zool., one kind of scales of the ganoid fishes, composed of an inner layer of bone, and an outer layer of shining enamel. They are often so arranged as to form a coat of mail.

© Webster 1913.