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
Dagetichthys lusitanica Dagetichthys lusitanica Dagetichthys lusitanica, commonly known as the Portuguese sole, is a species of flatfish native to the eastern Atlantic Ocean. Little is known of the abundance or behaviour of this fish, and the International Union for Conservation of Nature has rated its conservation status as being "data deficient". The Portuguese sole grows to a standard length of about . The general shape is oval, tapering somewhat towards the tail. Like other flatfish, the body is flattened laterally and the fish lies on its side, with both eyes on the right side; the upper eye is slightly in front of