A guide to the fossil invertebrate animals in the Department of geology and palaeontology in the British museum (Natural history) . efunnel-shaped (Fig. 22, h). The living alcyonarian, Clavu-laria, has a tubular skeleton with similar cross-canals, andthe organ-pipe coral, TuMpora, has tabulae either flat orfunnel-shaped and cross-canals running in the flat expansionsthat connect the tubes; therefore many place SyringoiJoraand the Favositidae with these Alcyonaria. In all thesegenera the tubes of eacli colony are of equal size, and doubt-less contained equally developed polyps. On the other sid
A guide to the fossil invertebrate animals in the Department of geology and palaeontology in the British museum (Natural history) . efunnel-shaped (Fig. 22, h). The living alcyonarian, Clavu-laria, has a tubular skeleton with similar cross-canals, andthe organ-pipe coral, TuMpora, has tabulae either flat orfunnel-shaped and cross-canals running in the flat expansionsthat connect the tubes; therefore many place SyringoiJoraand the Favositidae with these Alcyonaria. In all thesegenera the tubes of eacli colony are of equal size, and doubt-less contained equally developed polyps. On the other sideof this Case is Heliolites (sun-stone), in which the surfaceshows openings like little suns surrounded by smaller circularopenings; in section the colony is seen to be formed oftabulate tubes of two sizes. Heliolites and its allies areexplained by reference to Heliopora (see Table-case 1), aliving Alcyonarian, in which the larger tubes contain com-plete polyps, and the smaller ones contain simple sacs ofthe common flesh of the colony. Halysites, the chain-coral(Fig. 21 a, h), consists of tabulate tubes, flattened, and joined. h c Fig. 21.—Silurian Anthozoa, possibly Alcyonaria, from the Wenlock Lime-stone of Dudley, a, Halysites catenularius, natural size; h, some ofits tubes seen in section, to show the tabulae, slightly enlarged; c, Aulo-jjora, growing on a shell, enlarged | diameter. (From specimen K 2067,Table-case 8.) by their edges, with no connecting pores ; in some speciesall tubes are of equal size, in others some tubes are muchsmaller; it is probably an Alcyonarian. Aulopora, apparentlyan ally, grows in a low network over shells and corals(Fig. 21 c). A slab of Silurian limestone from Gotland,between Wall-cases 5 and 6, is largely composed of Favositesand Halysites. Table-case In the next Case are Silurian Zoantharia Eugosa or7- Tetracoralla. Here come the conical Omphyma with root-like supports (Fig. 22 a), the broadly spreading cups of COELENTEEA— CORALS. 53 ^
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