232 C(ELEXTEEATA. 



The body is seldom quite soft, or with a leathery framework ; as a 

 rule it has a calcareous stony polyparium with radial striations. 

 Separated sexes are the rule, but hermaphrodite polyps (Actinia) 

 are not seldom to be met with. The polyps very generally retain 

 their embryos for a long time, so that they are born eight or twelve 

 rayed, with rudimentary tentacles. Many give rise to coral reefs 

 and islands (figs. 175 179). 



1. ANTIPATHARIA. Mostly with only six tentacles, and horny skeletal axis. 

 Fam. Antipathidae. Polyp stocks with soft non-calcareous body, but with 



simple or branched axial skeleton. Only six tentacles surround the mouth, e.g., 

 Antipatlies Pall. 



2. ACTIXIARIA, with no hard structure. 



Fam. Actinidae, with soft body ; sometimes single animals with several 

 alternating circles of tentacles, Actinia L. ; sometimes connected in stolons 

 and aggregated to form stocks, Zoantkus Cuv. The former are able, by means of 

 their contractile foot, to leave their place of attachment and to move freely. 

 Many reach a relatively considerable size, and possess beautiful colours. Under 

 the name of sea anemones they are the ornaments of salt water aquaria. 

 Actinia mesemlryantliemum L. The skin sometimes secretes a glutinous mass 

 filled with nematocysts or a kind of membrane, Cerianthus Delle Ch. 



3. MADEEPORAEIA with continuous hard calcareous skeleton. 



(a) Aporosa. w 



Fam. Turbinolidae. Mostly single polyps with compact calcareous frame- 

 work, imperforate thecse, and well developed septa, the spaces between which 

 are open to the bottom. Turlinolia Lam., Flaldlum Less., Caryoplnjllia 

 Lam., C. cyatlnts Lam., Blastotrochus Ed. H. 



Fam. Oculinidse. Polyp stocks with hard usually branched polyparium, with 

 coenenchyma rich in calcareous matter, and but few septa in the cup of the 

 individual. Ocidina virr/inea Less., Indian Ocean. AvyrftiJtelia oculata L. 

 white corals of the Mediterranean. 



Fam. Astrse'idse, Star corals, Mostly massive polyp stocks with fused thecce, 

 and without coenenchyma. The septa have sometimes cutting edges, sometimes 

 toothed edges. The interseptal spaces are filled with horizontal partition walls. 

 Eusmilia Edw. The single animals are produced by fission and remain 

 connected only at their bases. They produce a cespitous polyparium, the 

 septal edges of the cup being cutting. Galaxea Okeii. The single cups arise 

 by gemmation, are free at the upper edge ; the septa have cutting edges. Astrcea 

 Lam., single cups fused throughout the entire wall. The septal edges of the 

 cup are jagged. Maandrlna Lam., the neighbouring cups fused to form long 

 valleys. M. Crassa Edw. H. 



Fam. Fungidae. Mushroom corals. Usually with large fiat single cups, some- 

 times polyp stocks ; without thecee, with numerous strongly developed septa, 

 toothed and connected by synapticulse. JFungia discus Dana., JJalomitra 

 Dana., ZtOjjJiosei'is Edw. II. 



(b) Perforata. 



Fam. Madreporidae, Madrepores. Polyps and polyp stocks with porous 

 coenenchyma and perforated thecae. Gastric cavity open at the bottom and 

 communicating with the central canal in the axis of the branched polyparium. 



