xxviii BRITISH FOSSIL CORALS. 



19. Genus Ctenophyllia. 

 Dana, Zoophytes, p. 169, 1846. 



Corallum pedunculate, but increasing very little by its basis, and terminated by a large 

 oval, almost flat, calicular surface ; the different series of corallites intimately united together 

 by means of their common walls, and without there being in general any coenenchyma ; the 

 gyri or calicular grooves very long, and the mural ridges thin. Columella lamellar, and 

 almost uninterrupted from one end of the gyrus to the other. In general, some traces of 

 pali. Septa rather closely set, slightly exsert, and delicately granulated. Dissepiments very 

 abundant, arched, and oblique ; sometimes simple, but in general producing a vesicular 

 mass. The common epitheca rudimentary, and covering only the inferior part of the common 

 exterior walls, in the upper part of which are costa, nearly equal, and more or less cristiform 

 near the margin of the calicular surface. 



Typ. sp., Ctenophyllia mceandrites, Milne Edw. and J. Haime, Ann. des Sc. Nat., 3 me serie, vol. x, p. 277 ; 

 Meandrina pectinata, La.ma.rck ; Madrep. mceandrites, Solanderand Ellis, Zooph., tab. xlviii, fig. 1. 



20. Genus Dendrogyra. 



Ehrenberg, Corall. des Roth. Meeres, p. 100, 1834. 



Corallum composite, having the form of a thick, massive, vertical column, in which the 

 corallites are placed perpendicularly to the axis, and constitute very tortuous gyri, 

 completely united by their walls ; mural ridges broad, flat, and compact ; grooves shallow. 

 Columella highly developed, and formed by a series of very compact, enlarged processes. 

 Septa very thick and closely set. Dissepiments large, but not crowded. 



Typ. sp., Dendrogyra cylindrus, Ehrenb., op. cit. ; Milne Edw. and J. Haime, Ann. des Sc. Nat., 3 me serie, 

 Zool., t. x, pi. vi, fig. 9. 



21. Genus Rhipidogyra. 



Milne Edw. and J. Haime, loc. cit., p. 281, 1848. 



Corallum composed of a single series of corallites and constituting a flabelliform or 

 tall tortuous mass, the lateral walls of which are always free from top to bottom. Columella 

 lamellar, but almost rudimentary. Septa exsert and crowded. Dissepiments abundant. 

 Costa delicate, in general subcristate near the margin of the calice. No epitheca, or only 

 a rudimentary one. 



Typ. sp., Rhipidogyra fiabellum, Milne Edw. and J. Haime, loc. cit. ; Lobophyllia fiabellum, Michelin, 

 Icon., tab. xviii, fig. 1. 



22. Genus Pachygyra. 

 Milne Edw. and J. Haime, loc. cit., p. 468, 1848. 



Corallum adherent by a very thick peduncle ; gyri with a narrow calicular groove, 

 and united by a very broad mass of dense coenenchyma. Columella lamellar. Septa 

 crowded. Costa delicate and granulated ; little or no epitheca. 



Typ. sp., Pachygyra labyrinthica, Milne Edw. and J. Haime, loc. cit. ; Lobop, flia labyrinthica, Michelin, 

 Icon., pi. lxvi, fig. 3. 



