Class 4. Osteichthyses a Telostomi:

• The endoskeleton is bony.
• A pair of gill openings confluent in the form of a single ventral slit or non-confluent as two lateral slits.
• Outer edges of the gills are free while their bases attached to bony arches.
• There are four pairs of gill arches, the fifth pair modified into tooth bearing lower pharyngeal.
• The gill is covered with gill cover (operculum).
• Branchial lamellae are supported by a double row of branchial rays.