Class Osteichthyes Diagnostic characters: 1. Bony endoskeleton 2. dorsal nares 3. two sets of paired fins 4. swim bladder (most species) Infraclass Teleostei Diagnostic characteristics: 1. homocercal tail 2. cycloid or ctenoid scales Ctenoid scale from Perca flavescens Perca flavcescens, the yellow perch (Mitchell 1814)