232 CCELEXTEEATA. 



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

 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 (tigs. 175 179). 



1. ANTIPATHAEIA. 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., 

 Antipathes Pal!. 



2. ACTIXIAEIA, with no hard structure. 



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

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

 and aggregated to form stocks, Zoanthus Guv. 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 mesembryantliemMm L. The skin sometimes secretes a glutinous mass 

 rilled with nernatocysts or a kind of membrane, Ccrintitlnis Delle Ch. 



3. MADREPORAEIA with continuous hard calcareous skeleton. 

 (a) Aporosa. 



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

 work, imperforate thecre. and well developed septa, the spaces between which 

 are open to the bottom. Turblnolia Laiu., Flalidlum Less., Caryopliyllia 

 Lam., C. ojatlnix Lam., Blastotrochus Ed. H. 



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

 coenenchyma rich in calcareous matter, and but fe\v septa in the cup of the 

 individual. Oculinn riryinea Less., Indian Ocean. Aiiq^iilu'lla oculata L. 

 white corals of the Mediterranean. 



Fam. Astrseidae, Star corals, Mostly massive polyp stocks with fused thecsE, 

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

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

 Emmilia 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. Galatea Okeii. The single cups arise 

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

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

 cup are jagged. Ma-dndr'nin Lam., the neighbouring cups fused to form long 

 valleys. M. Crassa Edw. H. 



Fain. Fungidae. Mushroom corals. Usually with large flat single cups, some- 

 times polyp stocks; without the<-a-. with numerous strongly developed septa, 

 toothed and connected by synapticuku. Jfungia d incus Dar.a., Halomitra 

 Dana., LnjiJioscris Ed\v. II. 



(/;) Pi'i'fiirittn. 



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

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

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



