Siderastrea 
PI. , figs. 
Corallum massive, rounded above, basal portion somewhat 
expanded. Greater diameter of base, 106 mm. , lesser, about 65 
mm.; height, 65 mm. 
Calices, polygonal, quite large, diameter (measured from 
summit to summit of wall) from 4,7 to 6.5 mm., 5 to 6 mm. the 
usual diameter. Hear the edges the calices are shallow, higher 
upon the corallum excavated and moderately deep. The outer 
ends of the septa are arched on the upper part of the corallum, 
may be somewhat flattened near the wall; lower down they may be 
depressed across quite a wide area, with a very shallow calicular 
cavity; in a few instances a depression corresponds in position 
to the upper edge of the wall. The wall is merely a zone of 
synapt icula. 
Septa very crowded, thin and numerous, from 60 to more 
than 70. They are so crowded that it is difficult to make out 
o ^ rt orio€ - np 4- s s p . n ov *. 
