31 
ORDERS 
BELONGING TO THE THIRD CLASS. 
1st Order. Polypi none, or not perceptible. 
2nd Order. Polypi apparent ; axe in articulated. 
3rd Order. Polypi apparent; axe articulated. 
No Orders belonging to the 4th Class* 
GENERA 
BELONGING TO THE FIRST ORDER OF THE FIRST CLASS. 
Cellepora. Submembranous, in concrete expan- 
sions. Cells projecting. 
Flustra. Concrete expansions, foliated ; submem- 
branous. Cells united in formation, and placed in 
series, on one or many surfaces. 
Pherusa. Flat and frondescent. Cells oblong, pro- 
jecting, and only on one surface. 
Electra. Branching. Cells campanulated, ciliated, 
and verticillatcd. 
