(Family): Mouth oblique, lower jaw protruding from the upper. Scutes on ventral midline. No lateral line. No spine in fins. Pectoral fin subthoracic. (Genus): No pelvic fin. Dorsal fin small, its origin far backwards from anal fin origin, located about midway of anal fin base. Maxilla elongated posteriorly, its tip reaching gill opening. Body strongly compressed. (Species): Scute series on ventral midline discontinuous below pectoral fin.
Distribution:
From Trinidad to Guiana.
Remarks:
Another species in this genus O. compressus has continuous scute series on ventral midline, without gap below pectoral fin. (Shimizu)