ACERINA.--All the teeth villiform, without canines; teeth on the vomer, but none on the palatine bones or the tongue. One continuous dorsal fin, of which the spinous portion consists of from thirteen to nineteen spines; two anal spines. Body rather low, with rather small scales. Bones of the skull with wide muciferous cavities; præoperculum denticulated. Small freshwater perches, of which _A. cernua_, named “Pope” in England, is the most common, and has the widest distribution in Central Europe and Siberia. The two other species have a more restricted range, _A. schrætzer_ being confined to the Danube and other rivers emptying into the Black Sea; and _A. czekanowskii_ to Siberian rivers. This genus is not represented in the Western Hemisphere. LUCIOPERCA.--Teeth in villiform bands, those in the jaws with additional canines; palatine bones toothed. Two dorsal fins--the first with from twelve to fourteen, the anal fin with two spines. Præoperculum serrated; scales small. The “Pike-Perches” are inhabitants of many lakes and rivers of the temperate northern zone. The European species is confined to the eastern two-thirds of the continent, and one of the most esteemed freshwater fishes; it attains to a length of three or four feet, and to a weight of from 25 to 30 lbs. It has been recommended for acclimatisation in England, and there is no doubt that in certain localities it might prove a valuable addition to the native fauna; but like all its congeners it is very voracious and destructive to smaller fishes. Two other species inhabit rivers of European and Asiatic Russia, and two or three the fresh waters of North America. PILEOMA.--All the teeth minute, villiform, without canines; teeth on the vomer and palatine bones. Two dorsal fins--the first with fourteen or fifteen spines. Body rather elongate, with small scales. Præoperculum not serrated. Small freshwater perches abundant in the United States. Like the following genus, and some others which need not be mentioned here, they can be regarded as small, dwarfed representatives of the preceding genera. The species seem to be numerous, but have not yet been sufficiently well distinguished. The latest and best account of them is by L. Vaillant, “Recherches sur les Poissons d’eaux douces de l’Amérique septentrionale (_Etheostomatidæ_),” in Nouv. Archiv. du Muséum d’Hist. Nat. de Paris, ix., 1873. BOLEOSOMA.--Allied to _Pileoma_, but with only nine or ten feeble spines in the first dorsal fin. North America. ASPRO.--Body elongate, cylindrical; snout thick, projecting beyond the mouth, which is situated at its lower side. All the teeth villiform, without canines; teeth on the vomer and palatine bones. Two separate dorsals. Præoperculum serrated; præorbital entire. Scales small. Two small Perches from the Danube and some other rivers of the continent of Europe, _Aspro vulgaris_ and _A. zingel_.