Slide showing six diagrams illustrating the 'heads of various polychaeta'. Slide shows six diagrams illustrating the 'heads of various polychaeta'. Each diagram is labelled with Roman numerals and letters which are explained in the following key: 'Fig 134. - Heads of various polychaeta (diagrammatic). A, polynoid; B, Syllid; C, Nephthys; D, Eunice; E, Phyllodoce; F, Trophonia: a, prostomium; c, normal cirrus; c', peristomial cirri; c2, cirrus of second segment; c3, cirrus of third segment; el1, point of attachment of elytron; p, palp: s, nuchal organ (ciliated pit); t, tenatcle; I, peristomium; II, III, IV, segments.' Late 19th to early 20th century