_The scales extend but rarely over the vertical fins, and the lateral line is generally present, continuous from the head to the caudal fin. All the teeth simple and conical; no barbels. No bony stay for the præoperculum._ A large family, represented by numerous genera and species in fresh waters, and on all the coasts of the temperate and tropical regions. Carnivorous. Fossil Percoids abound in some formations, for instance, at Monte Bolca, where species of _Labrax_, _Lates_, _Smerdis_ and _Cyclopoma_ (both extinct), _Dules_, _Serranus_, _Apogon_, _Therapon_, and _Pristipoma_ have been recognised. _Paraperca_ is a genus recently discovered in the Marles of Aix-en-Provence. A species of _Perca_ is known from the freshwater deposit of Oeningen. PERCA.--All the teeth are villiform, without canines; teeth on the palatine bones and vomer; tongue toothless. Two dorsal fins, the first with thirteen or fourteen spines; anal fin with two spines. Præoperculum and præorbital serrated. Scales small; head naked above. Branchiostegals seven. Vertebræ more than twenty-four. The “Freshwater Perch” (_Perca fluviatilis_) is too familiarly known to require description. It is generally distributed over Europe and Northern Asia; and equally common in North America, there being no sufficient ground for separating specifically the specimens of the Western Hemisphere. It frequents especially still waters, and sometimes descends into brackish water. Its weight does not seem to exceed 5 lbs. The female deposits her ova, united together by a viscid matter, in lengthened or net-shaped bands, on waterplants. The number of the eggs of one spawn may exceed a million. Two other species, _P. gracilis_, from Canada, and _P. schrenckii_, from Turkestan, have been distinguished, but they are very imperfectly known. An allied genus is _Siniperca_, from Northern China. [Illustration: Fig. 151.--Perca fluviatilis, the Perch.] PERCICHTHYS.--Differing from _Perca_ especially in the number of the fin-spines, which are nine or ten in the first dorsal, and three in the anal fin. The upper surface of the head scaly. These fishes represent the Freshwater Perches of the Northern Hemisphere in the fresh waters of the temperate parts of South America. Two species have been described from Patagonia, and one or two from Chili and Peru. LABRAX.--All the teeth are villiform, without canines; teeth on the palatine bones, vomer, and the tongue. Two dorsal fins, the first with nine spines; anal fin generally with three. Præoperculum serrated, and with denticulations along its lower limb; præorbital with the margin entire. Scales rather small. Branchiostegals seven; well developed pseudobranchiæ.