REPORT ON THE ALCYOXAKIA. 253 



ramifications, l)y the means of lateral buds arising from the individual meiiibcrs, but 

 in which the colonies are always without an axial skeleton. 



The various modifications of growth exhibited by the Cornularidse show that the 



group is a very diverse one. But though the forms are numerous enough, they are 



usually linked closely together, and have been readily derived from one another. The 



simplest representatives are to be met with in Cornidaria proper, in Rhizoxenia, and 



in one division of the genus Clavidaria. In these we distinguish (a) individual polyps 



in which the anterior portion of the body is either not retractile into a posterior part 



(as in Rhizoxenia), or can be drawn into a region definable as the calyx (as in 



Cornularia and Clavidaria), and (6) where the cylindrical tuljes or stolons arise from 



the bases of the polyps and unite the latter. The formation of new polyps by budding 



takes place on stoloniferous prolongations which are simple projections of the three 



body-layers of the polyps and include continuations of their alimentary cavities. In 



one group of Clavidaria, which we distinguish as " Memhranipoda," instead of there 



being cylindrical stolons between the polj^ps there is a flat basal expansion into which 



the prolongations of the polyps are continued as endodermic tubes. The basal 



expansion may jjresent the form of a thin plate on which the polyps are seated, or it 



may be thickened as a cceuenchymatous mass enclosing a portion of the polyps, with 



the bases of their alimentary cavities sunk therein. In this case the endodermal tubes 



arise not only from the base of the alimentary cavities themselves, but also from the 



lateral walls so far as they are enclosed by the coenenchyma, which is thus penetrated 



by a network of nutritive canals. This is the case in Anthelia, Sav., Syrnpodium, 



Ehrbg, Erythropodiurri, KoU., Callipodium, Verr., Sarcodictyon, Forbes, where, 



however, the ccenenchyma is still narrow and stolon-like. Another mode of growth is 



exhibited by Telesto, Lam., and Caloyorgia, M.-Edw. In these a polyp rises to a 



definite height from its basal surface or from a stolon ; this implies a consideraljle 



thickening of the polyp walls in order to afford the requisite support. Into this 



thickened wall fine endodermal canals jjenetrate from the alimentary cavities of the 



polyps, and from these buds may develop, rising at various levels on the lateral wall of 



the original polyp, but without direct connection with its alimentary cavity. These 



buds may again develop into long polyp-tubes and then give off secondary buds until 



a ramified arborescent form is the result. This attains its highest developjment in 



Cceloyoryia. A remarkable specialisation of this last type leads to the Penuatulid-like 



structures found in Pseudogorgia, KoU. 



As regards the skeleton very diverse conditions prevail. Cvrnularia forms only 

 an ecto-skeleton of a horny substance, surrounding the calyx tubes. In others spicules 

 are developed in the mesoderm. These may at times enter into such close mutual 

 connection that rigid calyx tubes are produced. This is well seen in Cyathopodium, 

 Verrill. where the condition of the Tubiporidse is shadowed out. 



