Soles have been found in the later Tertiary rocks. Solea kirchbergiana of the Miocene is not very different from species now extant in southern Europe. No remains referable to allies of the halibut or plaice are found in Tertiary rocks, and these relatively simple types must be regarded as of recent origin.
The Turbot Tribe: Bothinæ.—The turbot tribe have the mouth large, the eyes and color on the left side, and the ventral fins unlike, that of the left side being extended along the ridge of the abdomen. The species are found in the warm seas only. They are deeper in body than the halibut and plaice, and some of them are the smallest of all flounders. It is probable that these approach most nearly of existing flounders to the original ancestors of the group.
Perhaps the most primitive genus is Bothus, species of which genus are found in Italian Miocene. The European brill, Bothus rhombus, is a common fish of southern Europe, deep-bodied and covered with smooth scales.
Fig. 435.—Wide-eyed Flounder, Syacium papillosum Linnæus. Pensacola, Fla.
Very similar but much smaller in size is the half translucent speckled flounder of our Atlantic coast (Lophopsetta maculata), popularly known as window-pane. This species is too small to have much value as food. Another species, similar to the brill in technical characters but very different in appearance, is the turbot, Scophthalmus maximus, of Europe. This large flounder has a very broad body, scaleless but covered with warty tubercles. It reaches a weight of seventy pounds and has a high value as a food-fish. There is but one species of turbot and it is found in Europe only, on sandy bottoms from Norway to Italy. In a turbot of twenty-three pounds weight Buckland found a roe of five pounds nine ounces, with 14,311,260 eggs. The young retains its symmetrical condition for a relatively long period. No true turbot is found in America and none in the Pacific. Other European flounders allied to the turbot and brill are Zeugopterus punctatus; the European whiff, Lepidorhombus whiff-jagonis; the topknot, Phrynorhombus regius; the lantern-flounder, Arnoglossus laterna, and the tongue-fish, Eucitharus linguatula, the last two of small size and feeble flesh.
In the wide-eyed or peacock flounders, Platophrys podas in Europe, Platophrys lunatus, etc., in America, Platophrys mancus in Polynesia, the eyes in the old males are very far apart, and the changes due to age and sex are greater than in any other genera. The species of this group are highly variegated and lie on the sand in the tropical seas. Numerous small species allied to these abound in the West Indies, known in a general way as whiffs. The most widely distributed of these are Citharichthys spilopterus of the West Indies, Citharichthys gilberti and Azevia panamensis of Panama, Orthopsetta sordida of California, and especially the common small-mouthed Etropus crossotus found throughout tropical America. Numerous other genera and species of the turbot tribe are found on the coasts of tropical Asia and Africa, most of them of small size and weak structure.
Fig. 436.—Etropus crossotus Jordan & Gilbert. Cedar Keys, Fla.
Samaris cristatus of Asia is the type of another tribe of flounders and the peculiar hook-jawed Oncopterus darwini of Patagonia represents still another tribe.