The Spade-fishes
BODY compressed, usually greatly elevated, the anterior profile steep, the caudal peduncle short; scales ctenoid, moderate or small, densely covering soft parts of vertical fins; lateral line present, following curve of back; mouth small, terminal, and horizontal; premaxillaries slightly protractile; maxillary short, without supplemental bone; jaws with bands of slender, pointed, movable, brush-like teeth; nostrils double; preopercle very finely serrate or entire; gill-membranes broadly attached to the isthmus, the openings restricted to the sides; branchiostegals 6 or 7; pyloric coeca few; gillrakers very short; pseudobranchiae present; dorsal fins 2, somewhat connected, the first of 8 to 11 spines which are depressible in a groove; soft dorsal and anal fins high anteriorly, their bases thickened by a covering of scales; anal spines 3 or 4, short; caudal fin truncate or doubly concave; pectoral short, the rays all branched; air-bladder large, commonly bifurcate in front, and with 2 slender horns behind.