MADREPORARIA. 



Anthozoa of which the polyps are either simple or colonial; the basal ectoderm gives rise to a 

 continuous external calcareous skeleton, usually consisting of basal, peripheral, and radial elements. 

 Colonial polyps are in communication around the proximal termination of the column, and sometimes 

 by basal canals perforating the skeleton. Tentacles in alternating cycles, often with a knobbed or 

 swollen apex. Stomodaeum smooth or ridged, without gonidial grooves or siphonoglyphs. The mesen- 

 teries include a primary cycle of six pairs, appearing successively in bilateral pairs, two pairs of which 

 are directives, and usually a second series which arise antero-posteriorly, as isocnemic exocoelic pairs 

 all round the polyp and become arranged in cycles, or as bilateral pairs at one or more restricted 

 regions of the polyp. Mesenterial filaments simple, without lateral ciliated bands. Lower region of 

 gastro-coelomic cavity subdivided by septal invaginations, alternating with the mesenteries, sometimes 

 perforated by skeletal growths. Reproduction sexual and asexual; asexual reproduction frequent, 

 by gemmation and fissiparity. 



I.— ENTOCNEMARIA. 



MaDREPORARIA in which THK MKSENTEUIES always arise IX BILATERAL PAIRS, AND 

 BEYOND THE PROTOCNEMIC STACE THE INCKEASE TAKES PLACE WITHIN ONE OR BOTH OF THE 

 DIRECTIVE ENTOC(ELES. 



A.— SECTION PERFORATA. 



MaDREPORARIA in WHICH THE BASAL DISK FORMS CANAL-LIKE OUTGROWTHS PERFORATING 

 THE SKELETON, WHICH IN COLONIES PLACE THE DIFFERENT POLYPAL CAVITIES IN COMMUNICA- 

 TION. 



Family ]\r AJDRKPORm^*::. 



Genus MADREPORA Linnaeus." 



Polyps small, often dimorphic (axial and radial), forming- ramose, foliaceous, or incrusting- fixed 

 colonies, united one with another superficially by continuations of the column wall (coenosarc) without 

 lines of demarcation; pericalicular continuation of gastro-coelomic cavity by canals without mesenterial 

 prolong-ations. Free portion of column only slightly protrusible, more so in apical polyps; incapable of 

 overfolding; no sphincter. Tentacles of radial polyps six in number, equal, acute; tentacles of radial 

 polyps strongly bilateral in axial-abaxial plane, larval in extent of development, twelve in number, rarely 

 more; unicyclic, smooth, not knobbed at apex, iutrovertible. Stomodseal walls smooth. 



Mesenteries unicyclic, in Eiliriirihi(i-sta.ge. rarely more than six pairs, when increase takes place by 

 the addition of bilateral pairs within the two axial entocoeles; all filamentiferous. Septal invaginations 

 usually twelve, dicyclic, entoccelic and exocoelic, axial and abaxial often largest, interrupted below, unite 

 centrally ( columella) , forming six distinct mesenterial loculi which terminate gradually or are truncated. 

 Gastro-coelomic cavities in communication throughout colony by a basal canal system, as well as by 

 pericalicular canals. 



Asexual reproduction by columnar gemmation, rarely by fissiparous gemmation. 



Examples. — Madrepora iinu-icdtn Linn.; f(iriii»' jirolifeni (Lam.), <rri</iy>rn/'s (ham.). /"/////- 

 ata (Lam.). 



"" Colony very variable in shape, branching.', bu^h-shapeil, expaniling, flat, corymbiform, or foliaceous, peduni'ulate 

 or incrusting. Gemmation around the parent torallite and fn nn the siile ( if the other calices. Ca-nenchy ma abundant, 

 spongy, reticulate, spinulose, growing exogenously froui the porous walls of the corallites. Calices variable in shape, 

 projecting or immersed, but never all so; terminal calices, or some among the mass, longest or largest (parents). 

 Septa distinct, variable in solidity, two opposite primaries largest and nearly meeting. Twelve tentacles, and one 

 larger than the others. No columella. An endotheca may exist, which occasionally becomes tabulate." (Duncan. 

 1885, p. 183.) 

 542 



