From the time of Lamouroux and Goldfuss to the present, the group of organisms which we now characterise as Bryozoa, or Polyzoa, have received marked attention from naturalists. There has been, however, many misconceptions as to the true affinities of this, with other groups,—and many misunderstandings in consequence—but at the present time Polyzoa literature is becoming rather abundant, and the misconceptions are, to a large extent, things of the past. With regard to this preliminary paper, I may be allowed to say that my object in writing it, is to place before the student the aims and outcome of the various classifications of the Cyclostomata extant, not for any desire of contesting the conclusions of the authors referred to, but more for the purpose of keeping controversal matter out of my future papers. The divisions of the Polyzoa now generally recognised by naturalists:— I.—Cheilostomata. II.—Cyclostomata; and III.—Ctenostomata; were originated by Mr. Busk in his catalogue* of the Marine Polyzoa in the British Museum, and in the monograph of the Fossil Polyzoa of the Crag.† After the publication of the latter work, two elaborate papers followed from the pen of Professor Smitt, on Scandinavian Bryozoa,* who accepted the divisions, but not the synoptical arrangement of Busk. Professor Smitt, however, based his modified arrangement of the Cyclostomata, on apparently more solid ground than that of Mr. Busk, bnt many of his generic divisons were suggestive, rather than natural. Mr. Busk says: “ Although unprepared to follow Professor ...