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



4. Gersemia, Marenzeller, Denkschr. math.-nat. CI. d. k. Akad. Wiss. Wieii, Bd. xxxv. 



1877, p. 18 (Reprint). 



The colony consists of an upright stem with only a few simple branches, which bear 

 tufts of polyps, with non-retractile tentacular regions. Only the body- wall of the polyps, 

 the tentacles, and the cortical layers of the stem are furnished with spicules. The 



vi dual polyp-tubes appear to be indirectly continued into the large sap-canals. 



5. Gersemiopsis, Danielssen, Norske Nordhavs-Exped., Zool. Alcyonida, p. 103. 



The colony is branched, the branches again ramifying. The ccBnenchyma is feebly 

 developed ; canals wide. The polyps are long, cylindrical, and non-retractile. The 

 oesophagus is furnished with two flap-like j^rotuberances. The spicules are chiefly 

 clavates and subclavates. 



6. Drifa, Danielssen, loc. cit., p. 64. 



The colony is arborescent ; the main branches are thick and from them proceed 

 numerous branchlets, bearing the polyps. The polyps are closely set, elongate, non- 

 retractile, with well-developed calyces. The spicules, chiefly subclavate forms, are very 

 numerous in the stem, branches, and polyps. 



7. Duva, Koren and Danielssen, Bergens Museum, Nye Alcyonider, 1883, p. 1 ; 



Danielssen, Norske Nordhavs-Exped., 1876-78, ZooL Alcyonida, 1887, p. 37. 



Gersemia (pai's), Marenzeller, loe. cit., p. 18. 



The colony is upright and branched ; the terminal twigs bear tufts of polyps which 



are not retractile, and are furnished with long, spindle-shaped spiny spicules. The 



branches and twigs contain no spicules. In the cortex of the stem, short many-rayed 



spindles and double stars are to be found. - 



8. Eunephthya, Verrill, Amer. Journ. Sci. and Arts, vol. xlvii. p. 284, 1869; Proc. 



Essex Inst., vol. vi. p. 81, 1869. 



Nephthya, Savigny (pars), Polyp. Egypt. ; Danielssen, loc. cit., p. 87. 

 Ammothea, Marenzeller, loc. cit., p. 16. 



The colony forms an upright stem from which accessory branches are given ofl' on all 

 sides. These may again branch, or give origin directly to tufts of polyps. The latter 

 are large, non-retractile, and covered with thorny club-shaped or branched spicules, the 

 ends of which project beyond the surface. These occur only in the cortex of the stem, 

 not on the walls .of the canals. 



