174 THE GREAT BARRIER REEF. 



stage, and until attaining the dimensions of an inch or more in diameter, the coralla 

 are attached to a rigid stalk, after the manner of an ordmary mushroom, with the gills 

 developed on the upper surface. An illustration of this interesting development of Fiingia 

 crassitciitacnlata is furnished by the upper right-hand corner figure in Plate XXIII., and 

 also by Fig. 14 of Plate VI. of the chromo-lithographic series, wherein two young Fungiae 

 are growing from a single stalk. Soon after attaining to the dimensions illustrated in the 

 photographic figure, the young Mushroom-coral becomes detached, and falls to the ground, in 

 most instances leaving the stalk or stolon, it would appear, to develop a new bud. On account 

 of its essentially reproductive functions, the stolon is usually denominated a "nurse stock." 

 This interesting chapter in the life-history of the Mushroom-coral is of high biological signifi- 

 cance. It gives the strongest possible support to the assumption that all the existing free 

 Mushroom-corals sprang from an ancestral type that was permanentlj' stalked, in the same 

 manner as it is assumed that the existing feather-stars, Comatula?, which still in their early 

 youth pass through a temporary stalked condition, sprang from primaeval permanently-stalked 

 Crinoids. 



Another point worthy of note has to be recorded, in association with the photographs 

 obtained from livmg specimens of Fiiiigia cmssitcufaciilafa. The minds of biologists have been 

 considerably exercised within the last few years by the recognition that throughout an exten- 

 sive series of sea-anemones, and other Actinozoa, there is a marked tendency for the single 

 elongated mouth to become differentiated in such a manner, that it subserves the purposes of 

 the double incurrent and excurrent apertures of the higher invertebrata, and represents, in point 

 of fact, the primitive or ancestral prototype of the oral and anal apertures. By so early an authority 

 as the late Dr. P. H. Gosse, author of the classic treatise on " British Sea-Anemones," i860, the 

 presence of an imperfectly-closed tube or groove, at one of the opposite mouth angles only, 

 or at both, and thence continued down the side of the throat or stomodaeum, was recognised 

 and described in association with the title of the "gonidial groove." Its particular import, 

 however, was not discovered by this actinologist, who assigned to it the possible function of an 

 oviduct. Later investigations, while confirming its presence throughout a very extensive series 

 of Actinozoa, elicited the fact that its lining was beset with larger and stronger cilia than the 

 adjacent surface of the stomodaeum, and that the tube, under stated conditions, constituted a 

 very efficient incurrent channel, and obviously fulfilled a respiratory function. When, in fact, 

 respiration is in active operation, the borders of the elongated mouth of the Actinian are usually 

 brought together throughout a greater or lesser extent of their median area, such local occlu- 

 sion producing the phenomenon of the two apertures, the one fulfilling an incurrent and the 

 other an excurrent function. As this groove is a highly specialised functional organ, the dis- 

 tinctive title of the "siphonoglyphe " has been conferred upon it by Dr. S. J. Hickson.* 

 * "On the Ciliated Groove (Siphonoglyphe) in the Stomoda;um of the Aicyonavia." Phil. Trans. Part III. 1883. 



