Flatfish entire order was John Roxborough Norman's "Monograph of the Flatfishes" published in 1934. New species are described with some regularity and undescribed species likely remain. Hybrids are well known in flatfishes. The Pleuronectidae, of marine fishes, have the largest number of reported hybrids. Two of the most famous intergeneric hybrids are between the European plaice ("Pleuronectes platessa") and European flounder ("Platichthys flesus") in the Baltic Sea, and between the English sole ("Parophrys vetulus") and starry flounder ("Platichthys stellatus") in Puget Sound. The offspring of the latter species pair is popularly known as the hybrid sole and was initially believed to
Curlfin sole Curlfin sole The curlfin sole ("Pleuronichthys decurrens") is a flatfish of the family Pleuronectidae. It is a demersal fish that lives on soft bottoms at depths of between . Its native habitat is the subtropical waters of the eastern Pacific, from Prince William Sound, Alaska in the north to San Quintín, Baja California in the south. It can grow up to in length, and reach weights of up to , with females generally being larger than males. The curlfin sole is a right-eyed flatfish with large, closely set eyes and a small mouth. The upper surface is reddish brown to