Larvae have four pairs of gill slits. An ypsiloid cartilage is present. Bodies are dorsoventrally depressed and have fleshy dermal folds. The scapula and coracoid bones of the pectoral girdle are fused to form the scapulocoracoid. Vertebral centra are amphicoelous.
Ribs are unicapitate.
Neural arches of vertebrae lack foramina, and spinal nerves exit intervertebrally. The pubotibialis and puboischiotibialis muscles are fused together. Anterior glomeruli of the kidney are reduced or absent. Reproductive characters Fertilization is external. Epidermal lining is absent from the anterior cloacal chamber of females.