FAMILIES AKD GEJS^EEA OF THE MADREPOEAEIA. 



87 



mediate structure, united walls not very stout. CostsB subequal, 

 crested, bifurcating or plain near tbe base, and more cristiform 

 near the calicular surface. Epitheca rudimentary and inferior 

 Endotheca exists. 

 Bistrihution. — Becent. "West Indies, Brazils. 



Genus EuaxKA, U. de Fromentel, Desc. des Fol.foss. de V Stage 



Mocomien, p. 30 (1857). 

 Colony pedicellate inferiorly, convex on the upper and enlarged 

 surface. Corallites in series, intimately united by their walls. 

 Calicinal valleys meandroid in the centre of the colony, and ra- 

 diating and straight towards the circumference. Calicos indis- 

 tinct. Columella absent. Septa entire, arched above. Endotheca 

 well developed. A folded and complete epitheca. 

 JDhtribution. — Fossil. Cretaceous : Europe. 



Grenus Pachygtea, Milne-Edwards Sf Jules Haime, Compt. 

 Bend, de VAcad. des Sci. t. xxvii. p. 468 (1848). 



The colony is fixed by a thick peduncle, and is enlarged above. 

 It is composed of corallites united by a costal and exothecal 

 coenenchyma, which is dense and greatly developed, and reaches 

 up to a certain distance below the summit of the walls, Calices 

 in long, flexuous, narrow, shallow series. The columella is 

 lamellary, very thin, and continuous. Septa are entire, thin, 

 close; and the costse are fine, subplane, and granular. The 

 ridges have a space along their axis, which presents the top of 

 the intermural tissue. Epitheca rudimentary or none. Endo^ 

 theca exists. 



DistrihuUon. — Fossil. Cretaceous and Oolitic : Europe. 

 Tribe II. 



Grenus Diploeia, Milne-Fdwards ^ Jules Haime^ Hist. Nat. 

 des Corall. vol. ii. p. 401 (1857). 



Colony massive, spheroidal, hemispherical, or convex, with a large 

 fixed base. Corallites in long series, united by their costse, which 

 are greatly developed, and between which there is some exotheca. 

 The walls are thick, and in sections their upper edges are free 

 and distinct from those of the neighbouring series. Hence the 

 calicular valleys are separated by rather broad, convex, depressed 

 collines marked on either side by costae. The calicinal centres are 

 quite indistinct in the very sinuous valley-series, which are deep. 



