REPOET ON THE ALCYONARIA. 253 



ramifications, by the means of lateral buds arising from the individual members, 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 Coniularia proper, in Rhizoxenia, and 

 in one division of the genus Clavularia. Iii 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 Clavularia), and (h) where the cylindrical tubes 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 Clavularia, which we distinguish as " Membranipoda," instead of there 

 being cylindrical stolons between the polyps there is a flat basal expansion into which 

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

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

 may be thickened as a ccenenchymatous 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., Sympodium, 

 Ehrbg, Erythy-opodium, Koll., Callipodium, Verr., Sarcodictyon, Forbes, where, 

 however, the coenenchyma is still narrow and stolon-like. Another mode of grov\i;h is 

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

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

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

 thickened wall fine endodermal canals penetrate 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 development in 

 Ccelocjorgia. A remarkable speciaHsation of this last type leads to the Pennatulid-like 

 structures found in Pscudogorgia, KoU. 



As regards the skeleton very diverse conditions prevail. Cornularta 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 Tubiporidae is shadowed out. 



