Vol. 127, No. 2 October, 1964 THE BIOLOGICAL BULLETIN PUBLISHED BY THE MARINE BIOLOGICAL LABORATORY EMBRYOLOGICAL DEVELOPMENT OF THE SYLLID, AUTOLYTUS FASCIATUS (BOSC) (CLASS POLYCHAETA) l M. JKAX ALLEN Department />f Biology, ll'ilson ('//<//(', Clnnnhcrsbury, Pennsylvania, and Institute of Marine Biology, University of Puerto Rico, Mnyu</ucz. Puerto Rico The Syllidae are unusual among the polychaetes in that some genera of this family reproduce both asexually, by the formation of stolons from a parent stock, and sexually, by the union of gametes from male and female individuals which, in turn, originate from stolons produced asexually. In some instances in this family, some form of gestation accompanies sexual reproduction the young may develop in a ventral brood sac formed by the female, or eggs and larvae may remain indi-vidually attached to the parent (external gestation). A number of papers have been written on reproduction in syllids, and Saint-Joseph (1887) summarized the reproductive methods in the genus Aiitolytus and in the family as a whole. Since then. Potts (1911) has reviewed in considerable detail the various reproductive methods used by the four subfamilies of syllids, and recently Pettibone (1963) has given a brief summary of their reproductive methods. However, surprisingly little has been published on the embryology of this very interesting family of polychaetes. and most of this was written 50 to 120 years ago. Cleavage has been described and pictured in only a few papers on syllid reproduction (for example, Malaquin. 1893, the most extensive paper on syllids ; Viguier, 1884 only the first three cleav-ages are shown; Pierantoni, 1903; and Schneider, 1914). Descriptions and figures of syllid larvae are scattered throughout the literature (Oersted, 1845; Miiller, 1S55; Agassiz, 1863; Pagenstecher. 1863; Greeff, 1879; Viguier, 1884; Saint-Joseph, 1887; Pierantoni, 1903; Herpin, 1926; Okada, 1930; Dales, 1951: ct al). However, descriptions depicting a series of developmental stages from early cleav-age through several larval stages for any one species of syllid are rare. The writer has noted only two such descriptions in the literature (Viguier, 1884, and Pieran-toni, 1903) and these belong to a different subfamily (Exogoninae) than does Aiitolytus (Subfamily Autolytinae ). All figures in these two papers appear to be drawings of external views, and in Yiguier's paper, the series on E.rot/oitc </cni-mifera does not include the stages between 8-cells and gastrulation. 1 This research was supported by grants G-8775 and G-19958 from the National Science Foundation. 187 Copyright 1964, by the Marine Biological Laboratory
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