G. decaturensis -24 
Septa of variable thickness on the same specimen, usually 
moderately stout; on the thinner lamellae they are quite thick. 
The thickness of the septa seems to be correlated with the thick- 
ness of the colony* When the corallurn is thick the septa are 
thin and vice versa. The normal number is 24, though there are 
in some places a few less, in others a few more. The usual 
arrangement is six primaries extending directly to the axis, 
with a triplet group of secondary and two tertiaries between each 
pair. A directive plane could be observed in some calices, but 
the septa are too much damaged to permit discovering all the 
details of the arrangement. The margins are dentate, five to 
seven dentations on each longer septum. The faces with the usual 
granulations. Sjmapticula quite abundant, but not greatly croYfded, 
variable in thickness. 
Columella tangle well developed. 
The texture of the corallurn is of variable firmness, 
depending upon the thickness of the septal trabeculae, the synap- 
ticula, &c., however, it seems never to be especially dense. 
