0. crass o lame Hat a -22- 
In young corallites there are six systems of three cycles* 
As growth proceeds, the other orders of the fourth and sometimes 
of the fifth cycle are gradually added* Some systems are 
defective in certain orders, while others possess them. The 
largest corallites have four perfect cycles, and a fifth in two 
or three systems; the ninth order "being usually wanting* It is 
difficult, in the larger corallites, to distinguish the systems on 
account of the resemblance of the primary, secondary, and tertiary 
septa to each other. 
The primary septa are very thick externally, hut delicate 
and linear elsewhere; the linear part joins the rest suddenly, 
like the staff of a big-headed spear; at the junction the thick 
corners of the enlargement give off a lateral spine, like a piece 
of endotheca; near the costal end of the septa there are delicate 
lateral spines. The space between the sets of lateral spines 
is more or less square. The sedondary septa are very like the 
primary 
