182 COELENTERATA. 



Section 1. Scleraxonia (Pseudaxonia). 



Fixed upright branched colonies. The coenenchyma consists of a caualiferons 

 cortical layer (with spicules) in which the polyps are placed, and of a medullary 

 substance. The latter contains spicules (different in form from the cortical 

 spicules) which are generally tightly packed, and sometimes fastened together 

 by a horny substance, or cemented into a strong axis by calcareous matter. 

 Without epithelial layer round the central rod. 



Fam. 1. Briareidae. Coeneuchyma consists of a polyp-bearing cortex and 

 a medullary substance of closely packed spicules. These are either developed on 

 the surface of an upright shrubby colony, or the medullary substance is relegated 

 to the interior of a cylindrical stem, over which is spread the cortex. In tin- 

 latter case there is a more or less well-defined axis, which may be permeated by 

 nutritive canals. LeucocJJa (tray ; Solenocaulon Gray ; Semperina Kiill. ; Sul< ria 

 Studer ; AnthothelaVerr.; Paragorgia M. -Edw. ; Briareum Blainville ; Tituni- 

 deum Ag. ; Iciligorgia Ridley ; Spongioderma Ko'll. 



Fam. 2. Sclerogorgidae. An axis consisting of closely intercalated elongated 

 spicules with dense horny sheaths. The axis is surrounded by longitudinal 

 canals, into which there open the reticulated coenenchymatous canals, uniting 

 the polyps. Suberogorgia Gray ; Keroeidcs Wr. and St. 



Fam. 3. Melitodidae. Axis jointed, consisting of alternate portions of cal- 

 careous and soft horny substance. Melitodes Yerr. ; Mopsella Gray ; Acabaria 

 Gray; Psilricubariu Ridley; Wriyhtdla Gray; Clittlirnria Gray; Parisis Verr. 



Fam. 4. Corallidae. Axis of a dense calcareous mass of fused spicules ; 

 polyps dimorphic ; the siphonozooids are said to grow into autozooids. Corallium 

 Lam.; 0. rubrum, the red coral (Fig. 138) ; Pleurocorallium Gray. 



Section 2. Holaxonia (Axifera) 



Coenenchyma branched or simple, with cortical canaliferous layer and axial 

 rod, which is either horny, or of calcified horn, or of alternating joints of 

 calcareous matter and horn. Axial rod derived from a layer of ectoderm cells 

 invaginated at the base of the colony, and surrounding it as an epithelium 

 (Fig. 145). 



Fam. 5. Dasygorgidae. Simple or branched, coenenchyma thin, polyps 

 large ; both polyps and coenenchyma contain spicules. When at rest the 

 tentacles are folded over the oral disc. Strophogorgia Wright ; Chrysogorgia 

 Duch. and Mich. ; Heropliila Steenstrup ; Da-sygorgia Verr. ; Iridogorgia Verr. 



Fam. 6. Isidae. Axis consists of alternating horny and calcareous portions. 

 Bathygorgia Wright ; Oeratoisis Wright ; CaJlisis Verr. ; AcaneUa Gray ; IsidcUn 

 Gray ; Selcrisis Studer ; Primnoisis Wr. and St. ; Mojtsca Lamouroux ; Acan- 

 thoisis Wr. and St. ; Is is L. 



Fam. 7. Primnoidae. Axis calcareous and horny, basal attachment calcareous. 

 Polyps with club-shaped calycine portion. Operculum calycine formed by some of 

 the scale-like spicules of the calycine region, which shut over the tentacular region. 

 Callo~ostrun Wright ; Cctlyptrophora Gray ; Primnoa Lamouroux ; Stachyodes 

 Wr. and St. ; Calypterinus Wr. and St. ; Stenclla Gray ; Thouarella Gray ; 

 . / mphif aphis Wr. and St.; Plumarella Gray; Primnoella Gray; Caligorgia Gray. 



Fam. 8. Muriceidae. Axis horny ; spicules project beyond the surface of 

 coenenchyma ; operculum tentacular, formed by the spicules at the base of the 

 tentacles which close over the calyx when the oral region is retracted. Acan- 

 thogorgia Gray ; Paramuricea Ko'll. ; Hypnogorgia Duch. and Mich. : Muriccidcs 

 Wr. and St.; Clcmatissn Wr. and St. ; ViUogorgia Duch. and Mich.; Anthogorgin 



