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



Placogorgia, Wright and Studer. 



The only species of this genus {Placogorgia atlantica) occupies a quite isolated position 

 off St. Paul's Rocks, in the Atlantic. 



Acamptogorgia, Wright and Studer. 



Both the species found by the Challenger, Acamptogorgia arhnscula (Gray) and 

 Acamptogorgia alternans, are from the Pacific Ocean, Japan and Fiji ; if the species 

 described by Koch ^ as Muricea bebrycoides, n. sp., belongs to this genus, then its 

 geographical area must be extended to the Mediterranean. 



Echinogorgia, Kolliker. 



All the species of this genus belong to the Indo-Pacific Ocean, Echinogorgia sassapo 

 (Esp.) at the' Mauritius, Echinogorgia fxurfuracea (Esp.), Echinogorgia cerea (Esp.), 

 Echinogorgia cancellata (Verr.), and Echinogorgia intermedia, Std., off North-west 

 Australia, Echinogorgia pseudosassapo, Kol., at Torres Strait, Echinogorgia ramulosa 

 (Gray), at the Philippines, while Echinogorgia flabellum (Esp.) and Echinogorgia 

 umbratica (Esp.) have as localities the "East Indies." Echinogorgia aurantiaca 

 (M.-Edw.) has been found off Callao. 



Thesea, Duehassaing and Michelotti. 



Thesea guadalupensis, D. and M., is recorded from Guadeloupe ; Thesea gemmata, 

 Verrill, was obtained from deep water at St. Croix, in the West Indies. 



Acis, Duehassaing and Michelotti. 



Of the three species of this remarkable genus, one, Acis guadalupensis, D. and M., 

 was found off Guadeloupe, a second, Acis orientalis, Rid., at the Mauritius, while the 

 third, Acis pustidata, was found by the Challenger at Japan. 



Mu ricella, VerriU. 



The central area for the species of this genus would seem to be the East Indies ; 

 MuriccUa humosa (Esip.), Muricella tuberculata (Esp.), have not been rediscovered, and 



' Fauna und Flora des Golfes von Neapel, xv. p. 52. 



