This genus represents Pleuronectes in the Southern Hemisphere, but consists of three species only, which occur on the coasts of New Zealand, and are valued as food-fishes.
Other genera, with narrow unsymmetrical mouth, in which the upper eye is not in advance of the lower, and which have pectoral fins, are Parophrys, Psammodiscus, Ammotretis, Peltorhamphus, Nematops, Læops, and Poecilopsetta.
Solea.—Eyes on the right side, the upper being more or less in advance of the lower. Cleft of the mouth narrow, twisted round to the left side. Villiform teeth on the blind side only; vomerine or palatine teeth none. The dorsal fin commences on the snout, and is not confluent with the caudal. Scales very small, ctenoid; lateral line straight.
“Soles” are numerously represented in all suitable localities within the temperate and tropical zones, with the exception of the southern parts of the southern temperate zone, in which they are absent. Some enter or live in fresh water. Nearly forty species are known. British are S. vulgaris, the common “Sole;” S. aurantiaca, the “Lemon-sole,” which is rather a southern species, and inhabits, on the south coast of England, deeper water than the common Sole; S. variegata, the “Banded Sole,” with very small pectoral fins; and S. minuta, the “Dwarf-Sole.”—Allied to Solea are Pardachirus and Liachirus from the Indian coasts.
Synaptura.—Eyes on the right side, the upper in advance of the lower. Cleft of the mouth narrow, twisted round to the left side; minute teeth on the left side only. Vertical fins confluent. Scales small, ctenoid; lateral line straight.
Twenty species; with the exception of two from the Mediterranean and coast of Portugal, all belong to the fauna of the Indian Ocean.—Closely allied is Aesopia.
Gymnachirus.—Mouth very small, toothless. Scales none, lateral line straight. Eyes on the right side. The dorsal fin commences on the snout; caudal free. Pectorals rudimentary or entirely absent.
Two species from the Tropical Atlantic.
Cynoglossus.—Eyes on the left side; pectorals none; vertical fins confluent. Scales ctenoid; lateral line on the left side double or triple; upper part of the snout produced backwards into a hook; mouth unsymmetrical, rather narrow. Teeth minute, on the right side only.
Abundant in the Indian seas, and especially on the flat sandy shores of China. About thirty-five species are known, which rarely exceed a length of eighteen inches. They are easily recognised by their long narrow shape (which has been compared to a dog’s tongue) and the peculiar form of their snout.