182 COELENTEEATA. 



Section 1. Scleraxonia (Pseudaxonia). 



Fixed upright branched colonies. The coenenchyma consists of a canaliferous 

 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. Coenenchyma 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 the 

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

 nutritive canals. Leucoella Gray ; Solenocaulon Gray ; Semperina Koll. ; Suberia 

 Studer ; AnthothelaVen\', Paragorgia M.-Edw. ; Briareum Blainville ; Titani- 

 deum Ag. ; Iciligorgia Ridley ; Spongioderma Koll. 



Fam. 2. Sclerogorgldae. 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 ; Keroeides Wr. and St. 



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

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

 Gray ; Psilacdbaria Ridley ; Wrightdla Gray ; Clathraria 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.; C. 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, potyps 

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

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

 Duch. and Mich. ; Herophila Steenstrup ; Dasygorgia Verr. ; Iridogwgia Verr. 



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

 Bathygorgia Wright ; Ceratoisis Wright ; Callisis Verr. ; Acanella Gray ; Isidella 

 Gray ; Sclerisis Studer ; Primnoisis Wr. and St. ; Mopsea Lamouroux ; Acan- 

 thoisis Wr. and St. ; Isis 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. 

 Callozostron Wright ; Calyptrophora Gray ; Primnoa Lamouroux ; Stachyodes 

 Wr. and St. ; Calypterinus Wr. and St. ; Stenella Gray ; ThouareUa Gray ; 

 AmphilaphisWr. 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 Koll. ; Hypnogorgia Duch. and Mich. : Muriceides 

 Wr. and St. ; Clematissa Wr. and St. ; Villogorgia Duch. and Mich. ; Anthogorgia 



