. A textbook of invertebrate morphology [microform]. Invertebrates; Morphology (Animals); Invertébrés; Morphologie (Animaux). TYPE CCELENTERA. 115 ( of the ocean the simple forms which do not produce colonies are fiv(iuently found. mationsMps of the ^ has been pointed out, it seems prob- that the Anthozoa are to be traced bacic to a Scyphostoma-like polvo lacknig interradial funnels. No four-mesenteriedform, however is knovv^i" a large gap existing between the Scyphostoma and the Alcyonaria which aio probably the simplest Anthozoa known to us. The primitive Alcyona
. A textbook of invertebrate morphology [microform]. Invertebrates; Morphology (Animals); Invertébrés; Morphologie (Animaux). TYPE CCELENTERA. 115 ( of the ocean the simple forms which do not produce colonies are fiv(iuently found. mationsMps of the ^ has been pointed out, it seems prob- that the Anthozoa are to be traced bacic to a Scyphostoma-like polvo lacknig interradial funnels. No four-mesenteriedform, however is knovv^i" a large gap existing between the Scyphostoma and the Alcyonaria which aio probably the simplest Anthozoa known to us. The primitive Alcyonaria wore undoubtedly simple forms, and from tiiem to the Edwardsiie was not a very great step. By the formation of four additional mesenteries Ldwardsian condition became converted into the twelve-mesenteried con- dition which forms the ground-form of the Protactinia?, Zoanthea- and , the various stages seen in the ProtactinijB indicating the manner in which the condition has been brought about 'llie Cerianthe* seem to be offsets from the Edwardsian condition but it is diflicult m the present state of our knowledge to conjecture the affinities of the Antipatharia. It is noticeable that the members of all the orders except the Ilexac- tinue have a strictly bilateral arrangement and development of the mesen- teries ; this arrangement becomes gradually modified, first, by the ten- dency of the mesenteries to arrange themselves in pairs; second by the formation of secondary mesenteries; third, by a tendeiicv for these to appear in pairs ; fourth, by a tendency for such pairs to appear in all the intervals between the primary pairs. Thus the Anthozoa are forms which are gi-adually specializing away from the radial symmetry characteristic of all Coelenterales towards a bilateral symmetry, and the more pronounced radiality of the Hexactinije is a secondary SUBKINGDOM M?]TAZ()A. TYPE V (EL EN TEH A. Subtype pores in the walls
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