1属1種。本科魚類は9属が知られている。本属魚類は他属魚類から鱗がないこと,両顎側歯が歯帯をなすこと,前上顎骨歯を欠くこと,背鰭起点が胸鰭後端上方にあることで区別できる(Robins and Robins, 1970; 1976)。 (上野・佐々木)
Distinctive characters:
Gill-opening small, equivalent to eye, and placed below the insertion of pectoral fin. Anus notably anterior to mid-body; total length 3.4〜3.5 times of preanal length. Dorsal fin originates above tip of pectoral. Pectoral small, its length subequal to eye. Anterior nostril with tube near tip of snout; posterior nostril with low fleshy rim opened in front of eye. No teeth on premaxillary; 3〜4 excessively developed canines on vomer; teeth on maxillary and dentary about 5 rows in bands. Scale absent. Vertical fins, pectoral, and gill-opening with yellowish white margines.
Distribution:
Western Atlantic from Georgia to Suriname, and Hawaii in the Pacific.
Remarks:
Monotypic genus. The family with 9 genera and the present genus characterized by naked body without scales, large vomerine teeth, lateral teeth in bands, no premaxillary teeth, and dorsal origin over tip of pectoral (Robins and Robins, 1970; 1976). (Uyeno and Sasaki)