While examining a bowl of rock dredgings from the Mewstone Grounds near Plymouth, on 10th December, 1926, my attention was attracted by a handsome Phyllodocid worm which had evidently crawled out of a crevice in the broken rocks. On closer investigation the worm proved to be of an unfamiliar species and, of much greater interest, to possess a small secondary tail arising ventrally rather more than two-thirds of the way down the body (Fig. 1). Scale drawings, made at the time from the living animal, have recently been carefully checked by examination of the preserved specimen; only a few slight alterations have been found necessary.