The Mariposas
BODY ovate, compressed, and elevated, covered with minute, cycloid scales; head small, rather pointed; mouth small, terminal; no teeth in adult; premaxillaries protractile; only one dorsal fin, very long, elevated, falcate in front, no spines; anal low, not falcate; both fins depressible in a groove; pectoral fins large, falcate; a pit at base of caudal above and below, as in certain sharks.