522 RADIATES: POLYPS. 



CORALLID^:. This Family includes the Red Coral of 

 commerce, Corallium rubrum, Lamarck, which has the 

 axis calcareous, and very hard. Figs. 510 and 512 rep- 

 resent it alive. It lives in the Mediterranean. 



The Sub-Order of Alcyonacea comprises polyps which 

 are turbinate at the base, and which are found encrusting 

 foreign bodies. It embraces four families, Alcyonidae, 

 Xenidae, Cornularidse, and Tubiporidae. 



ALCYONID.E. This Family contains those in which 

 the polyps are united, forming lobed or arborescent clus- 

 ters of fleshy or coriaceous texture, filled with calcareous 

 particles. The Genus Alcyonium is the principal one. 



A. carneum, Ag., is found from Cape Cod northward, 

 and is attached to shells and stones in from eight to twenty 

 fathoms of water ; usually delicate flesh-color. 



TuBiPORiDuE. This Family contains those which have 

 the coral tubular, calcareous or semi-calcareous, and the 

 tubes not striate within ; color red. Fig. 5 14. 



SUB-SECTION II. 



THE ORDER OF ACTINARIA. 



This Order embraces polyps which have a well-devel- 

 oped abactinal region, conical or cylindrical tentacles 

 around the mouth, and the ambulacral spaces always 

 open. It divides into three sub-orders, Actinacea, An- 

 tipathacea, and Zoanthacea. 



The Sub-Order of Actinacea comprises those which 

 are free, capable of locomotion, and which have from ten 

 to hundreds of tentacles, and the mouth with special lobes 

 or folds. Most are simple, a few are compound, and a 

 few secrete from the base a horn-like deposit There are 

 five families, Actinidae, Thalassianthidae, Minyidae, Ily- 

 anthidae, and Cerianthidae. 



ACTINID^E, OR SEA-ANEMONE FAMILY. This Family 

 contains polyps which are more or less cylindrical, rising 



