I-AMIIilES AND GENEEA OE THE MADREPOEAKTA. 113 



exotheca. Calices sliglitly projecting, circular, united by costse. 

 Columella absent. Septa unequal, but not numerous. Endo- 

 thecal dissepiments stretcbing across tbe internal cavities of tbe 

 corallites like tabulas. 



Distribution. — Fossil. Oolite : England, Europe. Cretaceous : 

 Europe. 



Greuus Aeeacis, Milne-Edwards Sf Jules Saime, Gomptes Bend, 

 de VAcad. des Sci. t. xxix, p. 70 (1849). 



Colony massive and Astrseiform. Calices circular or deformed, 

 separated by coenenchyma. Coenencbyma spongy and ecbinulate 

 on tbe surface. Walls of corallites distinct from tbe surrounding 

 coenenchyma. Septa unequal, entire, principal uniting in tbe 

 axis. No columella. Endotbeca rudimentary, or as well- 

 developed borizontal tabuliform processes. 



Distribution. — Fossil. Eocene : Europe, Borneo. 



G-enus Psammophoea, E. de Fromentel, Pal. Fran^., Zooph. Terr. 

 cret. p. 494 (1879). 



Tbis genus was created for Stylopborinse witb a papillary 

 columella, before sucb a tbing was found. M. de Fromentel 

 subsequently found a coral in tbe d'Orbigny museum wbicb 

 presented tbe cbaracters of tbe Stylopborinse and also a papillary 

 columella. 



Tbe figures given (pi. 90. fig. 4) sbow a wretcbed specimen. 

 However it bas a compressed, tbin, laminate form witb calices 

 on botb sides. Tbere are four cycles of septa and fine costse. 

 Calices wide apart. 



It is not one of tbe Stylopborinse, and I place it bare witb 

 some doubt. 



Distribution. — Fossil. Cretaceous : Europe. 



VI. Alliance PENTACCENIOIDA. 



Agglomerate Astrseidse, increasing by gemmation. Corallites united 

 by the costse, more or less free above. Primary septa five in number. 



Genus Pentaccenia, d'Orb. 

 Genus Acanthoccenia, d'Orb. 



G-enus Pentaccenia, d' Orbigny, Bev. et Mag. de Zool. 

 p. 175 (1850). 

 Calices witb tbeir margins eitber subcircular and free, or poly- 



LIKN. JOITEN. — ZOOLOGY, VOL. XYIII. ' 8 



