In BRITISH FOSSIL CORALS. 



Family VI. 

 MADREPORIDtE. 



Corallum composite, increasing by gemmation and not by fissiparity. Ccenenchyma 

 abundant, spongy, and reticulate. Walls very porous, and not distinct from the ccenenchyma. 

 Septa lamellose, and well developed ; loculi free. 



First Tribe— MADEEPORINiE. 



Visceral chambers divided into two equal parts by two of the principal septa, which 

 are more developed than the others, and meet by their inner edge. 



1. Genus Madrepora. 



Lamarck, Hist, des Anim. sans Vert., t. xi, p. 277, 1816. 



Corallum composite, forming ramified, lobate, or fasciculate masses. Ccenenchyma 

 loose, and delicately echinulate. Calices projecting, with a thick margin. No columella. 



Typ. sp., Madrepora muricata, Ellis and Solander, Zooph., tab. lvii; Madrepora abrotanoides, 

 Lamarck, loc. cit., p. 280. 



Second Tribe— EXPL AN ARINtF. 

 Visceral chamber presenting at least six equally developed principal septa. 



2. Genus Explanaria. 



(Pars) Lamarck, Hist, des Anim. sans Vert., vol. ii, p. 254, 1816 ; Gemmipora, Blainville, 

 Diet, des Sc. Nat., vol. lx, p. 352, 1830. 



Corallum in general foliaceous. Ccenenchyma abundant, rather dense, and delicately 

 echinulate. Septa almost all of the same size. Columella spongy. 



Typ. sp., Explanaria crater, nob. ; Madrepora crater, Pallas, Eleuch. Zooph., p. 332, 



3. Genus Astreopora. 

 Blainville, Diet, des Sc. Nat., vol. lx, p. 348, 1830. 



Corallum massive. Ccenenchyma of a loose texture, and strongly echinulated. Septa 

 unequally developed. No columella. 



Typ. sp., Astreopora myriophthalma, Blainville, loc. cit. ; Astrea myriophthalma, Lamarck, op. cit., 

 p. 260. 



