104 



PKor. p. MAETiF Duncan's eevision oe the 



Alliance IX. Barysastr^oida. 



„ X. ASTROCCENIOIDA. 



„ XI. ISASTRiEOIDA. 



„ XII. Latim^androida. 

 Group-Genus Merulina. 

 Alliance XIII, Plerastr^oida. 



„ XIV. Tabuloida. 

 Group-Genus Moseleya. 



„ DiCTYOPHYLLIA. 



Sixty-eight genera are recorded, but revision admits of fifty- 

 five only. 



I. Alliance ORBICELLOIDA. 



Massive budding Astrseidse, with the corallites united by costse, exotheca 

 or intermediate tissue. Columella spongy or papillary. Septa dentated. 

 "With or without pali. 



Genus Heliastr^a, Ed. & H. 



Subgenus Ulastr^a, Ed. & H. 

 Genus Brachyphyllia, Reuss. 

 Genus Cyathomorpha, Reuss. 

 Genus Solenastr^a, Ed. & H. 



Subgenus Cyphastr^a, Ed. & H. 

 Genus Phymastr^a, Ed. & H. 

 Genus PLESiASTRiEA, Ed. & H. 

 Genus Antillastr^a, Duncan. 



Genera Ulastrcea, Ed. & H., and Cyphastrcea, Ed. & H., become 

 subgenera. 



The genera Agathiphyllia, Reuss, and Amphiastr^a, Etallon, are 

 absorbed. 



Grenus Heliastrjea, Milne-Edwards Sf Jules JEaime, Hist. Nat. 

 des Corall. vol. ii. p. 456 (1857). 

 Colony of various shapes, convex, subspherical, subplane, short 

 or tall, adherent, incrusting, or free. Corallites united by con- 

 tinuation of the exotheca, which exists between and beyond the 

 costae beneath the surface, rarely by the costse themselves. Walls 

 usually, but not invariably, stout. Calices with free circular 

 margins, more or less crateriform and elevated. Columella well 

 developed, spongy, and not projecting, with a plane free surface. 

 Septa exsert or not, with well-developed laminae, thicker near 

 the margins than near the columella, where there is often a 

 paliform tooth, dentate. Costse well developed, passing over the 

 surface for some distance ; where seen on the wall of a corallite, 



