REPORT ON THE ALCYONARIA. vii 



In all Alcyonaria, with the exception of the small family of the Haimeidse, which may 

 perhaps represent primitive forms, there is an all prevailing tendency to the production 

 of colonies by a process of gemmation. The gemmae do not arise directly from the 

 body of the main polyp, but from stolons which orginate as tubular processes from the 

 alimentary cavities of the polyps. Following the varied growth of these stolons, the different 

 colonial masses arise, either as narrow ribbon-like forms, or forming incrusting surfaces or 

 bushy structures or tree-like stems. As the highest type of development, we may regard 

 that type of colony in which a large number of individuals are so distributed, that each 

 receives an equal share of the nutritive supply, a condition most perfectly realised on 

 upright tree-like stems, where the branches and twigs bearing the individuals are arranged 

 in spirals. But such a colony is additionally favoured when a supporting skeleton 

 is differentiated so as to give the necessary support. The axis-forming Alcyonaria, for 

 which the title Gorgonacea may be retained, exhibit in their higher forms just such a 

 development, and reach it moreover in different ways, since the axis of the colonj" 

 may be differentiated in various ways from the skeletal elements. 



The simplest form of colony is that where the stem-polyps give off tubular processes, 

 which represent sac-like diverticula of the body and contain a cavity which is continuous 

 with the digestive canal of the polyp. On such stolons new polyps may arise by budding, 

 and these may in their turn produce polyp-bearing stolons. Such colonies are to be 

 found in the genera Rhizoxenia and Cornularia, and in some species of Clavularia. A 

 more compact colony may arise, if the base of the polyps in which the mesoderm is 

 greatly developed be broadened out so as to surround the polyps, and includes a series 

 of endodermic tubes from which new polyps can arise by budding. Such expansions are 

 known as the " ccenenchyma." They may give origin to flatly expanded crustaceous 

 colonies like those of Clavularia rosea, Studer, and Clavularia violncea, Quoy and 

 Gaimard. In these forms the ccenenchyma still remains as a thin membrane, on which 

 the individual polj^s are lodged, being only connected therewith by their bases ; with 

 a greater development of the ccenenchyma a larger portion of the polyp body becomes 

 associated therewith, the deeper part of the elongated alimentary cavity being included 

 in the coenenchymatous expansion, as in Anthelia, Sarcodictyon, Syrapodium, Erythro- 

 podium, Callipodium. Here the endodermic canals arise not only from the bases of the 

 polyps, but also from their lateral walls, as far upwards as the coenenchymatous thickening- 

 extends. The colony is, however, still crustaceous. 



Such an arrangement can only be advantageous, however, under favourable nutritive 

 conditions, where not alone the peripheral polyps but equally those in the centre of the 

 colony share in the nutritive supply, or else in cases where the colony spreads over some 

 irregular body, and thus brings the individual polyps into diverse relative positions, and 

 in contact with different strata in the water. This will depend, however, on the nature 

 of the foreign body which is so utilised. 



