(Family):Dorsal and anal fins present on posterior to midpoint of body. No luminous organ on shoulder. No adipose fin. Premaxillary and maxillary usually with teeth. (Genus):No scales on body. Nodular luminous organ present sporadically on body. Dorsal and anal fins opposite, both having more than 26 rays. Body covered with transparent thin membrane. (Species):Gill slit large, its upper tip reaching at level of eye center. Dorsal and anal fin rays less than 30. Body flabby, compressed.
Distribution:
Atlantic, southern Pacific, Indian Oceans.
Remarks:
Another species X. nodulosus has small gill slit, its upper tip reaching at level of upper end of pectoral fin base, and anal rays more than 32. (Shimizu)