The Relationship of the TetracoraUa to the Hexacoralla. 177 



but most decisive of all, it shows the pinnate or quadriseptate 

 manner of septal addition which was described by Faurot (1909). 

 This is a structure which has never been described in any of 

 the Hexacoralla but which, so far as present knowledge goes, 

 is universal among TetracoraUa. It is the one unfailing diag- 

 nostic character of the Zoantharia Rugosa (== TetracoraUa) as 

 defined by Milne-Edwards and Haime. 



Value of Perforations in Classification. — The occurrence of a 

 perforate structure in any of the coral lines was demonstrated 

 by Neumayr to have little classificatory value. A loose usage of 

 the terms "Perforata" and "perforate corals" has unconsciously 

 associated such forms as Favosites of the Tabulata, Calostylis, 

 and the genera of Hexacoralla Perforata. The family Poritidse 

 as defined by Milne-Edwards and Haime (1851) contained such 

 diverse forms as Pleiirodictyum and Protarea, as well as the more 

 usual forms of perforate Hexacoralla. Neumayr protested 

 against such a high valuation of porosity in classification, and 

 called attention to the great differences among the forms which 

 had been thus brought together on the basis of an artificial distinc- 

 tion. The term "Perforata" was finally restricted to the Hexa- 

 coralla. "The Hexacoralla form a connected series from the 

 most extreme perforate Alveopora and Porites to the compact 

 Astrcea; the fundamental character which connects them all is 

 the six-rayed arrangement of the septa. * * Calostylis is the 

 only known member of a distinct group of the TetracoraUa. 

 This group had a relation to the main line wdiich was similar 

 to the relation found to-day between the Perforata and Aporosa 

 of the Hexacoralla." (Neumayr 1889 6:282.) 



Neumayr's conclusion has been well supported by further 

 facts, especially the cases demonstrating the principles of parallel 

 development and convergence among the Anthozoa wdiich are 

 forcing the opinion more and more that this group is extremely 

 variable within narrow limits. 



Conclusion. — It is believed that the foregoing considerations, 

 especially the isolated geological occurrence, the order of appear- 

 ance of the septa, and the limited value of porosity in the char- 

 acterization of the larger groups, warrant a definite removal of 

 the genus Calostylis from the Hexacoralla to a separate family, 

 CalostylidcC, of the TetracoraUa. 



Trans. Conn. Acad., Vol. XXI 12 1917 



