| OCR Text |
Show 1886.] POSITION AND CLASSIFICATION OF SPONGES. 581 i. Group LITHISTID A, Zittel. Body stony, with a central gastral cavity or numerous vertical tubes. Spicules more or less clearly tetraxon, often branched. Besides these, sometimes monaxon spicules and flesh-spicules. The skeleton-spicules are interwoven so as to form a dense skeleton. 1. Familia RHIZOMORINID^E, Zittel. Spicules irregularly branched ; form irregular fibres, or are loosely interwoven. Forked anchors always present. Arabescula, Carter; Corallistes, Schmidt; Heterophymia, Pomel; Seliscothon, Zittel; MacAndrewia, Gray ; Azorica, Carter ; Leioder-matium, Schmidt ; and the fossil genera :-Cnemidiastrum, Coral-lidium, Hyalotragos, Pyrgochonia, Discostroma, Leiodorella, Episto-mella, Platychonia, Bolidium, Astrobolia, and Ghonella of Zittel; Plococonia, Pomel; Chenendopora, Lamouroux ; Verruculina, Zittel; Amphithelion, Zittel; Stychophyma, Pomel; Allomera, Pomel; Pleuromera, Pomel; Perimera, Pomel; Meta, Pomel; Marisca, Pomel; Pomelia, Zittel; Jereica, Zittel; Coelocorypha, Zittel; Scy-talia, Zittel; Stachyspongia, Zittel; Pachinion, Zittel. 2. Familia ANOMOCLADINIDJS, Zittel. Spicules rod-shaped with terminal tufts of branches. The approximating ends of the spicules coalesce and form knots. In this way a regular triaxial network is formed. Vetulina, Schmidt; and the fossil genera Mastosia, Cylindrophyma, Melonella, and Protachilleum, Zittel, and Palaiomanon and Astylo-spongia, Roemer. 3. Familia TETRACLADINID^E, Zittel. Spicules tetractinellid with terminal branches. Theonella, Gray ; Rhacodiscula, Zittel; Discodermia, Bocage ; Ka-liapsis, Bower bank ; Collectella, Schmidt; Collinella, Schmidt; and the fossil genera:-Aulocopium, Oswald ; Phymalella, Aulaxinia, Callopeyma, and Trachysycon, Zittel; Siphonia, Parkinson; Halli-rhoa, Jerea, Lamouroux; Marginospongia, d'Orbigny ; Nelumbia, Pomel; Polyjerea, Fromentel; Astrocladia, Zittel; Bolospongia, Hinde; Thecosiphonia, Zittel; Galymmatina, Zittel; Turonia, Mi-chelin ; Kalpinella, Thamnosponyia, and Pholidocladia, Hinde ; Ra-gadinia, Zittel; Plinthosella, Zittel; Spongodiscus, Zittel; Phyma-plectia, Hinde; Rhopalospongia, Hinde. To this Subordo also the fossil family Megamorinidae belongs. II. Group C HORISTIDA, Sollas. With tetraxon spicules of regular shape. i. Tribus Tetradina, Sollas. The chief spicules are tetract, with equal rays and candelabras. i. Subtribus Micro earnerce, nov. With small chambers. |
