liv BRITISH FOSSIL CORALS. 
Family VI. 
MADREPORID &. 
Corallum composite, increasing by gemmation and not by fissiparity. Canenchyma 
abundant, spongy, and reticulate. MW a//s very porous, and not distinct from the ccenenchyma. 
Senta \amellose, and well developed ; loculi free. 
First Tribe—MADREPORIN Ai. 
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 MapREPORA. 
Lamarck, Hist. des Anim. sans Vert., t. xi, p. 277, 1816. 
Corallum composite, formmg ramified, lobate, or fasciculate masses. Caenenchyma 
loose, and delicately echinulate. Cadices projecting, with a thick margin. No columella. 
Typ. sp., Madrepora muricata, Ellis and Solander, Zooph., tab. lv; Madrepora abrotanoides, 
Lamarck, loc. cit., p. 280. 
Second Tribe—EXPLANARIN &. 
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, 
Dict. des Se. Nat., vol. lx, p. 352, 1830. 
Corallum im general foliaceous. Caenenchyma abundant, rather dense, and delicately 
echinulate. Sepa almost all of the same size. Colwmella spongy. 
Typ. sp., Explanaria crater, nob.; Madrepora crater, Pallas, Eleuch. Zooph., p. 332. 
3. Genus ASTREOPORA. 
Blainyille, Dict. des Se. Nat., vol. Ix, p. 348, 1830. 
Corallum massive. Canenchyma of a loose texture, and strongly echinulated. Septa 
unequally developed. No columella. 
Typ. sp., Astreopora myriophthalma, Blainyille, loc. eit. ; Astrea myriophthalma, Lamarck, op. cit., 
p- 260. 
