prostomium shortly subcordate, well rounded in front, incurved caudally.
prostomium: The region in front of the mouth; the preoral part of the head.
prostomium of usual general form; consisting of fourteen or fifteen rings.
prostomium with a lateral process or horn on each side in front, notched in front at middle.
prostomium wider than long, deeply bilobed, the median tentacle inserted deeply in the intervening incision.
prostomium generally small, sometimes prolonged, but never bearing tentacles or processes.