Order Pleuronectiformes

Diagnosis:

• Adults have asymmetrical skulls with both eyes on same side
• Larvae are symmetrical and free-swimming in plankton until metamorphosis, which involves migration of one eye to the other
• Color on blind side usually pale
• Fins usually spineless
• Pelvic fins have less than seven rays
• Base of pelvic fin attached to cleithrum
• Gas bladder present
• Usually demersal
• Ctenoid scales on the eyed side; cycloid scales on blind side

Remarks: Batts (1964) published a dichotomous key for the scale characteristics of adult flatfish of Puget Sound, Washington. However, some characteristics used by Batts are not applicable to preserved material. For example, the number, angles, and orientation of ctenii are not particularly useful characteristics since the ctenii are generally lost, or at the least, damaged during sediment burial. Characteristics reported that are also stated by Batts are noted with a citation.