1 BRITISH FOSSIL CORALS. 



20. Genus Pachyseris. 



Milne Edw. and J. Haime, loc. cit., p. 72, 1849. 



Corallum similar to Agaricia, excepting that the corallites belonging to the same 

 trench are completely blended together. Columella well developed and dense. 



Typ. sp., Pachyseris rugosa, nob. ; Agaricia rugosa, Lamarck, Hist, des An. sans Vert., t. ii, p. 243. 



21. Genus Phyllastrea. 



Helioseris, Dana, Zooph., p. 269 ; Milne Edw. and J. Haime, loc. cit., p. 72, 1849. 



Corallum composite, composed of frondiform expansions. Calices circumscribed, sub- 

 mammillate, and arranged around the parent corallite, which remains larger than the others. 

 Columella tubercular. 



Typ. sp., Phyllastrea tubifex, Dana, loc. cit., tab. xvi, fig. 4. 



22. Genus Haloseris. 



Milne Edw. and J. Haime, loc. cit., p. 72, 1849. 



Corallum composite, forming foliaceous, crispate, lobulate expansions, the upper surface 

 of which is covered with very long radii, and shows only obsolete calices. Columella 

 rudimentary. 



Typ. sp., Haloseris lactuca, Milne Edw. and J. Haime, loc. cit. 



23. Genus Leptoseris. 



Milne Edw. and J. H?.ime, loc. cit., p. 72, 1849. 



Corallum composite and adherent ; the basal walls rising so as to constitute a sub- 

 crateriform disc, in the centre of which is situated a large parent corallite, surrounded by 

 smaller ones. CaVces very imperfectly circumscribed, but well radiated. Septa very long. 

 Columella rudimentary. 



Typ. sp., Leptoseris fragilis, Milne Edw. and J. Haime, loc. cit. 



Sub-order 2. 

 ZOANTHARIA PERFORATA. 



Corallum composed essentially of porous sclerenchyma ; with the septal apparatus well 

 characterised, and consisting of sis primitive elements, but being sometimes represented 

 only by series of trabiculse. Dissepiments rudimentary ; no tabulae. 



The principal character of this section of Zoantharia is furnished by the structure of 



