CORALS FROM THE LOWER GREENSAND. 71 
so as to constitute by their union a series of complete tabule, subdivided by the primary 
septa, and distant from each other about one fifth of a line. Exothecal dissepiments much 
resembling the preceding ones. Diameter of the calices, and depth of the fossula, about 
one line and a fourth. 
Fossil from the lower greensand at Redhill cutting, Atherfield, in the Isle of Wight, 
and at Peasemarsh. 
The specimens here described belong to the Museum of the Geological Society, and had 
been named by Mr. Lonsdale. The propriety of establishing a new generical division for 
this remarkable coral, was very judiciously pointed out by that indefatigable paleontologist ; 
but, guided by reasons which we do not quite understand, he refers, with a sign of doubt, 
this same species to the Cyathophora of M. Michelin, a genus which, in our opinion, does 
not differ from true Sfyna. The genus Holocystis differs from our genus Stawria by its 
extra calicular gemmation, and its costulated walls. It is the most modern representativé 
of the great division of Zoantharia rugosa, which becomes predominant in the Palaeozoic 
formations, and is principally characterised by the tendency to a quadrate arrangement of 
the constitutive parts of the Corallites, whereas in the other sections of Zoantharia, six is 
the fundamental number of the radiate organs. 
