CCELENTERATA : ACTINOZOA. 153 



B. ORDER RUGOSA. Characterised by the possession of a sclerodermic 

 corallum, usually with septa and tabulae combined, the former being in 

 multiples of four. The corallites are always distinct, and are never united 

 together by a cosnenchyma. The septa are usually incomplete, but are 

 never porous, and never bear synapticulse. The order is divided into the 

 following four families : 

 Family I. Stauridce. 



Corallum simple or composite ; septa incomplete ; united by lamellar 



dissepimnts ; four large primary septa, forming a cross. 

 Family 2. Cyathaxonidce.. 



Corallum simple ; septa complete ; no dissepiments or tabulae ; with- 

 out four primary septa. 

 Family 3. Cyathophyllida. 



Corallum simple or composite ; septa incomplete ; tabulse generally 



present. 

 Family 4. Cystiphyllida. 



Corallum simple, composed chiefly of a vesicular mass, with but 

 slight traces of septa. 



