CYATHOPHYLLOIDEA. 



285 



obsolete, and the symmetry becomes more or less radial. A true 

 columella may or may not be present, and the corallum may be 

 simple or composite. 



The Cyathophylloids, so far as certainly known, are confined to 

 the Ordovician, Silurian, Devonian, and Carboniferous deposits, and 

 are thus wholly Palaeozoic. 



Fig. 161. — Structure of Cyathophylhim hetcrofthylhim, from the Middle Devonian of Gerol- 

 stein. A, Transverse section of the corallum, slightly enlarged ; b, Longitudinal section, also 

 slightly enlarged, showing the outer vesicular zone (e), and the central area of anastomosing 

 tabulae (t). This is one of the species of Cyathophylhim in which a "fossula"is not clearly 

 recognisable, the symmetry thus becoming completely radial. The septa nearly reach the centre, 

 and their inner portions are considerably thickened. (Original.) 



Upon the ground of a close structural resemblance between the genus 

 Cyathophyllum itself and the recent genus Moseleya, Mr Quelch, as pre- 

 viously noted, has proposed the removal of all the Cyathophy Hides to the 

 Aporose Madreporarians, and the placing them in the immediate vicinity 

 of the Astrceidcp. ; but this change can hardly be accepted. It is true 

 that there are certain species of Cyathophyllum which are so far similar 

 to Moseleya that they show an almost complete radial symmetry, a " fos- 

 sula " not being distinctly developed, while a tetrameral arrangement of 

 the septa is not recognisable. Even within the limits of the genus 

 Cyathophyllum itself, there are, however, species with a well-developed 

 fossula and a distinctly bilateral arrangement of parts ; while other 

 allied genera are as conspicuously bilateral as is the genus Zaphrentis, 

 and possess a "fossula" of precisely the same type as that of the latter. 

 Moreover, through such genera as Omphyma and Campophyllum a com- 

 plete transition is effected between the typical Cyathophylloids and the 

 typical Zaphrentoids. Lastly, through Cystiphyllum it becomes easy 

 to pass from Cyathophy 11 inn or Actinocystis to such aberrant types as 

 Gojiiophylliwi and Rhizophyllum. 



Family 1. Cyathophyllidaz. — The chief family of the Cyatho- 

 phylloid corals is that of the Cyathophyllidce, comprising all those 

 members of the present section in which the septa are smooth, and 

 consist of a median plate (" primordial septum ") thickened on both 

 sides by a layer of stereoplasma or secondary calcareous deposit. 



