The first example of this, apparently little known, species of Parasitic Crustacean appears to have been noted by Professor Otto. The celebrated Swedish naturalist Retzius was, however, the first to give, in 1829, an anatomical description of it. He named it Lernœa Dalmanni. His description was accompanied by several figures, which, though in many respects imperfect, enable one to recognise the chief external characters of the animal. He found three specimens at Christian Sound, in the nasal cavity of Raia Batis. Von Nordmann obtained from Rudolphi the specimen discovered by Otto, but it was so injured, that he adopted, in his account of the anatomy of the animal, the description of Retzius. Some years afterwards, in 1836, Kröyer added it to the Danish fauna. He states that he obtained two specimens from the nasal chamber of a skate brought to him by a fisherman from Aal-back, and that specimens from Iceland had been for several years in the possession of the Natural History Society. As naturalists had now begun to subdivide the old Linnean genus Lernæa into various genera, Kröyer added this animal to the genus Lerneopoda of De Blainville, and, continuing its specific name, termed it Lerneopoda Dalmanni.