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



suggest the provisional abandonment of KoUiker's genus. Wardella has been established 

 by Gray for Xe7iia indivisa, Sars. The statement that it exhiljits an internal axis formed 

 of spicules precludes its being placed in the family Xeniidse. 



Family V. Organic m. 



Organinx, Danielssen, Norske Nordhavs-Exped. 1876-78, Zool. Alcyonida, p. 130. 



Organidus, Danielssen, loc. cit., p. 137. 



In this genus the colony is deficient in ccenenchyma ; the individual polyps arc 

 elongated and united together so as to form a short upright stem. 



The polyps are long, cylindrical, soft ; the collected polyps are attached by a slightly 

 widened base. The polyps are retractile ; both polyp body and tentacles are well furnished 

 with spicules. The sexes are separate. 



Family VI. Alcyonida. 



Alcyonidx, Verrill, ex parte, Proc. Essex Inst., vol. iv. No. v., 1865, p. 148. 

 Alcymidie + Sarcophytidx + BeUoneUadge + Nidalidce, Gray, Ann. and Mag. Nafc. Hist., ser. i, vol. 

 iii. pp. 123-127. 



Polyp-stock fleshy, sometimes simple, sometimes irregularly branching, the liasal 

 portion, which forms a stem, generally without polyps. A thick ccenenchyma surrounds 

 the long polyp tubes up to the retractile oesophageal portion. The digestive cavities of 

 the polyps communicate with each other by a system of large and small nutritive canals. 

 In some genera there is a dimorphism (siphonozooids and autozooids). 



The Alcyonidae exhibit a higher degree of colonial formation than the Xeniidse. The 

 poly|3 tubes are very long, and are united in strands which may even form a basal axis 

 more or less rapidly broadened out so as to form a series of lobes or twigs on the 

 terminal portions of which the polyps are found. A ccenenchyma always surrounds the 

 polyp tubes up to the oesophageal region, and into this portion the rest of the polyp may 

 be retracted. The ccenenchyma is studded with spicules which may acquire a special 

 form and abundance in the stem region. The polyp tubes are connected by a system of 

 endodermic processes, which have their origin in the tubes and give rise to fresh polyps. 



Tlie species of Bellonella seem related to Nidalia. The polyp tubes, which are 

 surrounded by a ccenenchyma with large spicules, end in projecting calyces, within 

 which the tentacular portion may be retracted. Bellonella and Cereopsis are also nearly 

 related, if they are not, as we think, to be united in a single genus. Cereopsis bocagei, 

 Kent, seems synonymous with Nidcdia atlantica, Studer and Iphethyrus speciosus, W. 

 Koch. 



