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Show 576 DR. R. VON LENDENFELD ON THE SYSTEMATIC [Dec. 2 1 , Classis SPONGIiE, auctorum. Ccelenterata with branching canal-system, the organs of which are developed from cells of the mesogloea or primary ™ e s ™ f r m; With simple epithelia, with entodermal collar-cells, and witnouc movable appendages and cnidoblasts. I. Subclassis CALCAREA, Grant. Sponges with a skeleton composed of calcareous spicules. I. Ordo CALCISPONGI^E, Blainville. The only order, with the characters of the subclass. I. Subordo H O M O C O E L A , Polejaeff, emend. The entodermal epithelium consists exclusively of collar-cells. 1. Familia ASCONIDAE, Hackel. Simple sac-shaped gastral cavity with smooth surface. Leucosolenia, Polejaeff, Ascetta, Ascissa, Ascilla, Ascaltis, Ascor-tis, Asculmis, Ascandra, Hackel. 2. Familia H O M O D E R M I D H E , Lendenfeld. The gastral cavity forms caecal outgrowths, which resemble the tubes of Syconidae. Ascaltis canariensis, Hackel, Ascaltis lamarckii, Hackel, and Homoderma sycandra, Lendenfeld. 3. Familia LEUCOPSID^E, Lendenfeld. A colony of Ascon-persons which are imbedded in the thick mesoglcea. There are narrow inhalant pores and wider exhalant ones. The latter lead into a pseudogaster. Leucopsis, Lendenfeld, and some species of Pseudonardorus-forms^ II. Subordo H E T E R O C C E L A , Polejaeff, emend. The entodermal epithelium is differentiated into collar-cells, which are found in the walls of the ciliated chambers only, and into flat pavement-cells, which clothe the walls of the exhalant canals and gastral cavity. 4. Familia SYCONIDJE, Hackel. With regular, radially disposed cylindrical ciliated chambers, which open direct into the sac-shaped gastral cavity. I. Subfamilia Syconince, Lendenfeld. The unbranched ciliated chambers remain isolated in their distal part. Sycon, Polejaeff, the subgenera of Hackel's Syconidae which terminate with the syllable " aya." I divide this subfamily according to Hackel's scheme into the seven genera Sycetta, Sycissa, Sycilla, Sycaltis, Sycortis, Syculmis, and Sycandra. |