1 spine and first ray of ventrals not separated from the rast of the fin
1 spine and first ray of ventrals separated from the rast of the fin; the last ray of ventrals connected by membrane to the bases of pectorals; gill opening reduced to a small alit behind opercle
2 branchial opening on upper surface of head; preopercular process with a spine at its base, directed forwards; head and body depressed; last rays of ventrals united by a mombrane with bases of pectorals
2 branchial opening lateral, looking more or less backwards; peropercular process without a spine; last rays of ventrals connected by membrane to the bases of pectoral; body more or loss cylindrical; operole without free flap