28 THE ANTHOZOA 



From this description it is clear that the relation of the zooid cavities to 

 the axis is much more intimate in the Axifera than in the Pseudaxonia. 



FAMILY 1. DASYGORGIDAE. Colonies simple or branched. Axis 

 horny and calcified. Zooids large, placed far apart, non-retractile, infold- 

 ing their tentacles over the oral disc when at rest. Spicules smooth, 

 needle-like or fusiform. Genera Dasygorgia, Verrill ; Chrysogorgia, 

 Duchassaing and Michelotti. FAMILY 2. ISIDAE. The axis consists of 

 alternate horny and calcareous segments, the calcareous matter being 

 amorphous. There are three sub-families. 1 . CERATOISIDINAE. Spicules 

 in the form of smooth needles. Genera Bathygorgia, P. Wright ; 

 Ceratoisis, P. Wright ; Callisis, Verrill ; Acanella, Gray ; Isidella, Gray ; 

 Sclerisis, Studer. 2. MOPSEINAE. Spicules in the form of dentate scales. 

 Genera Mopsea, Lamouroux ; Primnoisis, Wright and Studer ; Acan- 

 thoisis, Wright and Studer. 3. ISIDINAE. Zooids retractile in a thick 

 coenenchyme ; spicules stellate, warty. Genus Isis, Linnaeus. 

 FAMILY 3. PKIMNOIDAE. Axis horny, calcified. Zooids with a caly- 

 cine moiety stiffened by calcareous scales. Tentacular moiety retractile 

 within the calyx, the opening of which can be closed by an operculum 

 of eight scales. SUB- FAMILY CALLOZOSTRINAE. Genus Callozostron, 

 P. Wright. SUB- FAMILY CALYPTROPHORINAE. Genus Calyptrophora, 

 Gray. SUB-FAMILY PRIMNOINAE. Genera Primnoa, Lamouroux ; 

 Stachyodes, Wright and Studer ; Calypterinus, Wright and Studer ; Stenella, 

 Gray ; Thouarella, Gray ; Amphilaphis, Wright and Studer ; Plumarella, 

 Gray ; Primnoella, Gray. FAMILY 4. MURICEIDAE. Axis horny ; zooids 

 divided into three regions a proximal calycine, a median retractile, and 

 a tentacular non-retractile. Tentacles at rest infolded, provided at their 

 bases with an armour of stout spicules, forming a false operculum. There 

 are twenty-three genera of Muriceidae, the best known being Acanthogorgia, 

 Gray ; Paramuricea, Kolliker ; Villogorgia, Duch. and Mich. ; Bebryce, de 

 Phillipi; Acis, Duch. and Mich.; Eumuricea, Verrill. FAMILY 5. PLEX- 

 AURIDAE. Axis horny or horny and calcified ; zooids partially or wholly 

 retractile, without opercula. Genera Eunicea, Lamouroux ; Plexaura, 

 Lam. ; Plexaurella, Kolliker ; Psammogorgia, Verrill ; Eitnicella, Verrill ; 

 Platygorgia, Studer. FAMILY 6. GORGONIDAE. Colonies erect, branched, 

 usually in one plane. Zooids bilaterally or biradially disposed on stem 

 and branches ; retractile. Spicules small, fusiform. Genera Gorgonia, 

 Linnaeus ; Eugorgia, Verrill ; Platycaulos, Wright and Studer, Lophogorgia ; 

 M. Edwards ; Stenogorgia, Verrill ; Callistephanus, Wright and Studer ; 

 Swiftia, Duch. and Mich. ; Danielssenia, Grieg ; Xiphigorgia, M. Edw. ; 

 Hymenogorgia, Valenciennes ; Phycogorgia, Val. 



ORDER 5. Stelechotokea. 



Under this name are (here for the first time) included all those Synal- 

 cyonacea in which a much elongated mother zooid forms the stem or axis 

 of the colony, the daughter zooids being borne as lateral buds upon the stem. 

 The colonies are erect, simple, or branched, or may be plumose. When 

 they are branched, secondary zooids, developed as buds from the stem or 

 mother zooid, form the axes of the branches, and tertiary zooids are 

 budded off on each side of them. The secondary and tertiary zooids, though 



