256 



Descriptions of New Species of Corals- 

 FROM THE Australian Tertiaries. 



By J. Dennant, F.G.S. 



PART V. 



Plates V. and VI. 

 [Read October 21, 1902 ] 



The corals next described, though somewhat aberrant from 

 the type species in regard to their costse, should, I think, be 



placed under Milne-Edwards and Haime's genus Platytrochus. 

 They are much compressed, and the longitudinal axial fossa 

 contains a series of papilli, free superiorly, which might be 

 mistaken for pali only that they are too iiTegularly placed, 

 and, moreover, vary in number in separate individuals of the 

 same species. These papilli not only occujpy the fossa proper, 

 but tend to spread beyond, especially in the lateral portions 

 of the calice. They constitute the superior extension of the 

 columella, which, lower down, is formed by the fusion across 

 the central fossa of processes from the margins of the principal 

 septa. 



The several authors who have described species of Platy- 

 trochus from Alabama, the type locality, are not agreed con- 

 cerning the structure of the columella. Edwards and Haime 

 describe it as essential, fascicular, and terminated by a papil- 

 lose surface*. De Gregorio, in describing P. Claihorn^nsis, 

 says that the columella is false, irregular, and formed of the 

 pali.f Duncan, who diagnoses the genus, remarks: — ''The 

 columella is essential, elongate, and fascicular, and has a free 

 papillary edge. ^ ^ ^ There is a lamellar, fascicular colu- 

 mella." t Finally, Vaughan, who discusses the genus at length 

 in his admirable monograph of the Eocene and Lower Oligocene 

 Coral Faunas of the United States, sums up his conclusions 

 thus : — "Columella false, formed by the fusion of lobes from the 

 inner margins of the septa, or by the fusion across the axial 

 space of the inner margins of the septa.'' i^ 



* Annales sei. nat., 3rd ser., vol. IX., p. 247. 

 fMon. de la Faune Eocenique de I'Ala., p. 255. 

 Ij: Revision of Madreporaria, p. 18. 



§ Monographs of the U.S. Geological Survey, vol. XXXIX., pp. 73-4, 

 Washington, 1900. 



