146 THE VOYAGE OF H.M.S. CHALLENGER. 



Family VI. G o R G o N i D ^, Verrill. 



Gorgonidai, Dima,, pro parte, Zoophytes, p. 65L 



Gorgoniacex, Milne-Edwards, ^?-o ^;a?-fe, Hist. Nat. des Coralliaires, t. i. p. 144. 



Gorijoniacea, K'uWiker, p7-o 2Jarte, Icones Histiol., p. 139. 



Gorgonidx, Verrill, Trans. Connect. Acad., vol. i. p. 38G and footnote (reprint), 1869. 



The group Gorgoniacess of Milne-Edwards included those Alcyonaria which possessed 

 a solid axis, consisting of corneine and but very slightly effervescing on the application 

 of a strong acid ; in this differing from the forms of Gorgonellidae ; while they differed 

 from the Primnoids and Muriceids in the nature of their spicules. 



KciUiker separated the group into two divisions — the Euniceidae and the Gorgoniacese. 



Verrill, though as far as we know not characterising the group, has accepted KoUiker's 

 division as equivalent to a family, in which sense it is taken here. He has well defined 

 many of the genera belonging thereto. 



Species of the following genera are to be found in the Challenger collection : — 



Platycaulos, n. gen. 

 Callistephanus, n. gen. 



Lophogorgia, Milne-Edwards. 

 Leptogorgia, Verrill. 



Gorgonia, Auct. 



Genus Platycaulos, n. gen. 



Colony branched, the branches in one plane, anastomosing. The axis is horny, flattened ; 

 with a calcareous centre and calcareous particles interspersed amid the horny layer ; the 

 nutrient canals surrounding the central axis almost as in Plexaura. Polyps prominent, 

 on the sides of the stem and branches ; retractile within verrucae. Ccenenchyma 

 moderate, like shagreen. Spicules, straight and curved spiny spindles and stellate forms. 



In their Memoire sur les Coralliaires des Antilles, Duchassaing and Michelotti estab- 

 lished a new genus Thesea for the Gorgonia exserta of Ellis and Solander, placing this 

 genus as "intermediaire entre les genres Muricea and Primnoa." Afterwards in the 

 Supplement to their work they state that they had confounded this species with another 

 for which they had intended the genus Thesea [Thesea guoxlalupensis), and they make 

 the genus Swiftia for the Gorgonia exserta, E. and S. Both these genera are placed in 

 their division of the Primnoacese with scale-like spicules in the coenenchyma. 



The type specimens of Siviftia exserta, D. and M., not being at Turin it is not easy to 

 say what form these authors referred to. The original description of Ellis and Solander ^ is 

 as follows : — " Gorgonia teres sparse ramosa, ramulis alternis, osculis octovalvulis alternis, 

 polypis octotentaculatis exsertis, carne squamulis albis vestita, osse subfuscocorneo." The 

 specimen described was two feet in height, ver}^ loosely branched, with long slender 



" Nat. Hist, of Zoophytes, p. 84. 



