ganoidean

[Eng., ., ganoid; -ean.] A. As adj.: The same as GANOID, a. (q. v.) B. As substantive: 1. Sing .: The same as GANOID, 8. (q. v.) 2. Pl .: The order Ganoidei (q. v.). găn-61-dě-1, gan-61-dě-a, s. pl. [Masc. or neut. pl. of Mod. Lat. ganoi deus .] [GANOID.] IMG:content-0322.png:[blocks in formation] A. Eurynotus crenatus; B. Dapedius granulatus; c. Palæoniscus Voltzii; D. Amblypterus striatus. Ichthy.: The name given by Aga iz to one of the four orders into which, chiefly for paleontological purposes, he divided the cla of Fishes. It has since been adopted by Profs. Müller, Owen, Huxley, ., but with certain modifications. The e ential character of the fishes belonging to the order is that they have Ganoid-scales (q.v.). These const i tute the exoskeleton. The endoskeleton is cartilag inous instead of o eous. There are generally two pairs of fins; the first ray is usually a strong spine. The tail is generally heterocercal. The few living species are mostly freshwater, but marine forms must once have abounded. The ganoids commenced at least as early as the deposition of the Upper Silurian Rocks, and have continued, though their relative importance much diminished, till now. The order has been divided into: Section 1.-Lep i dog a no ide i. Sub-orders: (1) Amiadæ; (2) Lepidosteidæ; (3) Platy so midæ; (4) Cro opterygidæ; (5) A can tho didæ. Section 2.-Placoganoidei. Sub-orders: (1) Ostracoste:; (2) Chondrosteidæ.