148 Zoological Society : — 



lax cells in the interior of the young branchlet as epithelial tissue ; 

 but the inner surface of the tube of the axis is quite smooth and 

 simple, and the branchlets never become large like the main stem. 



This coral cannot be considered as a solid stem becoming hollow, 

 as the last-formed (younger) parts at the end of the branches are in 

 the form of a foliaceous expansion, which gradually folds up toge- 

 ther on itself, coalesces, and forms a tube nearly of the same dia- 

 meter as the main stem. The large apertures which occur in the 

 stem and base of the branches, and communicate with the central 

 cavity, are the parts of the expanded lamina which have not been 

 closed in when the other portions of the tube were formed. 



The specimen described evidently grew in a nearly horizontal po- 

 sition ; for one side of the main stem and branches is entirely without 

 any cells, and the branchlets on the same side are fewer than on the 

 other, showing that this part was beneath, and not exposed to the 

 light. I do not give this as the generic or specific character, as it 

 may be only incidental to the specimen — a fact that can only be 

 determined by the examination of a' larger number of examples. 

 Mr. Holdsworth has suggested that it may be the same as or allied to 

 Gorgonia trichostemma of Dana (Zoophytes, 665, t. 59. f. 3) ; but 

 Dana does not describe the main stem as tubular. But the coral is, 

 like many others in his work, so badly figured and described that it 

 is impossible to determine with any certainty what it is intended to 

 represent. Milne-Edwards seems to have been equally doubtful (see 

 Coralliaires, i. 154) as to its affinities. 



The genus Coelogorgia of Milne-Edwards (Coralliaires, vol. i. 

 p. 191) should be placed in the same family. It is described as 

 arborescent, very branching, and with slender cylindrical branches 

 with scattered, subcylindrical, elongate polype-cells. Only one spe- 

 cies is known, viz. C. pahnosa, from Zanzibar. 



Among the specimens preserved in spirits in the same collection 

 there is also a new form of Alcyon, which seems to me to be a type 

 of a new genus allied to Xenia, but quite distinct from it both in the 

 form of the cells and in the polypes being completely retractile. It 

 has some characters in common with my genus Nidalia, described 

 in the 'Proceedings of the Zoological Society,' 1835, p. 6, and 

 figured, Radiata, PI. III. fig. 2, but differs from it in the surface of 

 the coral being minutely granular, and not spiculose. 



Bellonella. 



Coral cylindrical, formed of a number of subcylindrical tubes ag- 

 glutinated together and forming at the top a hemispherical head of 

 subcylindrical prominent cells, which are angular at the tip. The 

 outer surface of the coral is minutely granular. The polypes are 

 completely retractile ; the base of their tubes is strengthened with 

 very minute spicula, placed in a longitudinal series parallel to each 

 other. 



1. Bellonella granulata. (Woodcut, opposite page.) 



Hub. Bellona Reefs. 17 fathoms (T. M. Rayner, Esq.). 



