THE ANTHOZOA 



35 



Order 6. Coenothecalia. 



CJuiracters — Synalcyonacea with a calcareous skeleton composed of 

 lamellae of calcite forming a dense corallum resemblin" that of the 





Fl.:. XVIII. 



1. — Surface view of a portion of a fully tirowii colony of Heliopora coei-ulea, Pall., showing 

 two calices with thWr pseiidosepta ; the openings of the coenenchynial tubules, the superficial 

 echinulations, and tlie sliallow canals between them in which the superlicial network of solenia 

 lies in the living condition. 



L'.— A single zooid with the adjacent soft tissues of llcliopora coerulea, as seen after removal 

 of the .skeleton by decalcification ; seniidiagrammatie. ^', the distal retractile moiety of the 

 zooid, bearing eight pinnate tentacles; Z-, tlie i)roxinial calicular moiety of the same; ec, the 

 continuous slii-ft of ectcclenn which clothes the surface of the colony ; .«/), the superficial 

 network of solenia lying directly beneath the ectodenn ; rt, coenenchymal tubules. 



3. — Diagnim illustrating the mode of growth and architecture of a colony of Udinporn. /A, 

 calyx of mother zooid ; /", Z-', etc., calices of daughter zooids successively fonned amongst the 

 coenenchymal tubules ; tt, tabulae. 



4. — .Surface vinw of a tangential section through the surface of a colony oi Hdidites porosus, 

 Goldfuss, showing three calices, each with twelve pseudosepta imbedded in a coenenchyme con- 

 sisting of numerous vertical coenenchymal tubules (solenia) of approximately hexagonal shape. 



5. — Diagnini illustrating the essential structure of the corallum in //e/i'oywro. and Ilelinlitex. 

 Ct, coenenchymal tubules, the walls of each of which are composed of twelve sejarate laminae, 

 which take a .share in the coinfiosition of the walls of six adjacent tubules. In the centre of the 

 figure a calicular cavity is indicated fonned by the arrest, complete or partial, of a group of 

 nineteen coenenchymal tubules numbered l-xix. The outlines of the arrested tubules are 

 indicated by ilotted lines. 



imperforate Madrejjoraria, and developed from a .speciali.sed layer of ecto- 

 derm cells (caliculilast.s). The corallum exhibits a number of larger 

 calices, provided with a variable number of radial pseudosepta, sunk in a 

 coenenchyme composed of numerous closely set vertical tubules, with 

 calcareous walls, which are disposed vertically to the surface of the 



