Pleuronectidae

“Flounder (Pleuronectidae) is confined to shallow areas.”

Sea of Okhotsk large marine ecosystem

“The abnormalities in Pleuronectidae to which I have referred are of the kind usually regarded as due to arrested development.”

Hormones and Heredity

“Reversed specimens occasionally occur in many species of Pleuronectidae, and if the determinants for a reversed head and a normal body were united in one zygote, the curious abnormality observed might be the result.”

Hormones and Heredity

“The diagnostic characters, of some of the species of Pleuronectidae have been mentioned in an earlier part of this volume, in order to point out that they have no relation to differences of habit or external conditions.”

Hormones and Heredity

“Pleuronectidae which appears to stand in direct contradiction to the conclusions drawn by me concerning scales in general.”

Hormones and Heredity

“T.H. Morgan, in a volume published some years ago, [Footnote: _Evolution and Adaptation_.] put forward the extraordinary view that the Pleuronectidae arose from symmetrical fishes by a mutation which was entirely gametogenetic and entirely independent of habits or external conditions, and then finding itself with two eyes on one side of its head, and no air-bladder, adopted the new mode of life, the new habit of lying on the ground on one side in order to make better use of its asymmetrically placed eyes.”

Hormones and Heredity

“It is possible that the case differs from other secondary sexual characters as the antlers of stags in one respect, namely, that the Dab (_P. limanda_), the Sole, and other species of _Solea. _ and several other Pleuronectidae have what are called etenoid scales -- that is, scales furnished with spines on the posterior edge -- and since the ordinary scales of the Plaice are reduced, the spinulation of scales in the mature male Plaice is not a new character but the retention of a primitive character.”

Hormones and Heredity

“Finally, the task was done, and I was again set upon alcoholic specimens ” this time a remarkable lot of specimens representing, perhaps, twenty species of the side ” swimmers or Pleuronectidae.”

Louis Agassiz as a Teacher