Helena Molina Urena has written:

'Distribution of the eggs and larvae of some flatfishes (Pleuronectiformes) off Washington, Oregon, and northern Calfornia, 1980-1983' -- subject(s): Flatfish fisheries

The flatfish are an order (Pleuronectiformes) of ray-finned fish, also called the Heterosomata, sometimes classified as a suborder of Perciformes. The name means "side-swimmers" in Greek. * ~Heterosomata~ * ~Perciformes~ * ~side-swimmer~

Major angling flatfish include dab, turbot, plaice, flounder, brill, and Dover sole. Other names of flatfish are Pacific sanddab, and a variety of sole including sand sole, butter sole, and rock sole.

You are purchasing Sole. Sole is a member of the flat fish in the order: Pleuronectiformes They are included in a class with fish such as Flounder, Halibut and Plaice.

The fillet is the type of cut, boneless and often skinless. It makes the cooking of this cut of fish easier and demands less preparation. See link below for a picture.