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ANTHOZOA. 



The existing Anthozoa are constructed on one of two types ; 

 they either have eight tentacles and no more, or, like the common 

 Sea-Anemone, they have a number of tentacles. Where there are 

 only eight tentacles, as in the noble red coral, each is fringed at its 

 sides, or, in technical terms, is pinnate ; when the tentacles are 

 niunerous they are non-pinnate. A certain number of palaeozoic 

 corals had a symmetry of four. We may therefore speak of Tetra- 

 coralla,^ Hexacoralla,^ and Octocoralla.^ 



Both of the latter may have (i.) soft bodies without spicules, (ii.) 

 horny axes (horny corals), (iii.) a continuous limestone skeleton 

 (stony corals) ; the Alcyonaria may have scattered spicules. 



The Hexacoralla, or Zoantharia, commence at the eastern end of 

 the Gallery, next the Hydrozoa ; the Octocoralla, or Alcyonaria, 

 commence at the western end of the Gallery. 



The organisation of the Alcyonaria is illustrated by large 

 diagrams ; the first, that of Monoxenia darwini, is very possibly only 

 a larval stage of some Alcyonarian ; but it shows some of the 

 essential characters of the group. These are a sac-like body, with 

 an axial gastric cavity, giving off eight compartments, on the 

 partition walls of which are developed the gonads or reproductive 

 elements. 



The organism seldom remains single ; developing a stolon or 

 creeping process, it gives rise to bud after bud, and so forms a 

 colony, as in Clavidaria (Figs. 1 and 2) or Alct/onium (Fig. 3), 

 diagrams of which are shown. There are also some excellent water- 

 colour sketches of Clavularians taken from life, and presented by 

 Prof. Hickson, F.R.S. 



The creeping process or stolon is well seen in the small prepa- 

 ration of the organ-pipe coral (Tubipora) ; as shown in Fig. 4, this 

 is seen to be a small flat plate, from which the tubes are beginning 

 to rise up. 



Sivc Rugosa. « Sive Zoantharia. ' Sive Alcyonaria. 



F 2 



