FAMILIES AlfD GENERA OF THE MADBEPOEAEIA. 165 



IV. Pamily ANABACIAD^. 



Madreporaria Eungida simple or colonial. Septa trabeculate 

 and fenestrated. Synapticula small. Dissepiments absent. 

 Wall indistinct. 



Genus Anabacia, d'Orb. 

 Genus GenabaciAjEcI. & H. 



Grenus Ats'abacia, d^Orligny, Note sur les Polyp, foss. p. 11 

 (1849). 



Corallum simple, free and without a trace of adherence, plano- 

 convex er biconvex in sbape. The upper surface bas a central 

 shallow fossette without a true columella. Tbe septa are very 

 numerous, close, uniting, and are continued over the edge to tbe 

 base, wbere tbeir free edges are in the position of costae. Tbey 

 extend from the base vertically to tbe upper surface, are tra- 

 beculate and perforate, and delicately spined or crenulate at their 

 free edge. There is no basal wall, and the septa unite by 

 synapticula. 



Distribution. — Fossil. Jurassic : England and Europe. 



Genus G-eistabacia, 3filne-Edioards ^ Jules Haime, Compt. Mend. 

 Acad, des Sci. t. xxix. p. 71 (1849). 



Colony sublenticular, base naked and perforate. A central 

 calice surrounded by one or two circles of smaller size with con- 

 fluent septo-costse. Septa trabeculate, perforate, thin, close 

 rather numerous, crenulated where free. Calicular fossette not, 

 deep. No basal wall. 



Distribution. — Fossil. Middle and Inferior Oolite : Europe. 



Transitional group. 

 V. Family PLESIOPOEITID^. 



Eungida with trabeculate and regularly perforate septa. 

 Synapticula between the septal laminae in the iuterseptal loculi. 

 Sclerenchyma trabeculate. Dissepiments may or may not exist. 

 Wall existing or not, and imperforate. Epitheea may exist and 

 be well developed. 



