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Show 1886.] POSITION AND CLASSIFICATION OF SPONGES. 579 3. Familia ROSSELLID^E, F. E. Schulze. The dermalia have no centripetal ray. Lanuginella, O. Schmidt; Polylophus, F. E. Schulze ; Rossella, Carter ; Acanthascus, Bathydorus, Rhabdocalyptus, Crateromorpha, Aulochone, Caulocalyx, and Aulocalyx, F. E. Schulze. ii. Tribus Amp hi di scop ho r a, F, E. Schulze. Amphidiscs in the limiting membranes. Hexaster absent in the interior. A basal tuft is always present. The ciliated chambers appear as somewhat irregular sac-shaped extensions of the membrana reticularis. 4. Familia H Y A L O N E M A T I D ^ E , Gray. Numerous pentact pinnulae in the dermal and gastral surfaces. 1. Subfamilia Hyalonematince, F. E. Schulze. Calyculate, with a well defined oscula-area on the upper surface. Hyalonema, Gray; Stylocalyx, F. E. Schulze; Pheronema, Leidy ; and Poliopogon, Wyville Thomson. 2. Subfamilia Semperellince, F. E. Schulze. Without gastral cavity and terminal oscula-area, with root-tuft. Semperella, Gray. To this Subordo the fossil families Receptaculitidae and Monakidae belong. n. Subordo DICTYONINA, Zittel. The parenchymal hexacts early coalesce in a regular manner, so as to form a firm skeleton. i. Tribus TJncinataria, F. E. Schulze. With uncinates. i. Subtribus Olavularia, F. E. Schulze. With radially situated clavulae. 1. Familia FARREID^E, F. E. Schulze. The skeleton forms a single layer; from the joining points conical extensions arise, in a direction vertical to the surface of the network. Farrea, Bowerbank. 2. Subtribus Scopularia, F. E. Schulze. With radially situated scopulae. 2. Familia EURETID^E, F. E. Schulze. Branched and anastomosing tubes. The skeleton-net forms several layers. Eurete, Carter ; Periphragella, Marshall; and Lefroyella, Wyville Thomson. 38* |