558 SYDNEY J. HICKSON. 



&c., but he overlooked entirely the tabulae and the " siphono- 

 glyphe." 



A. Anatomy of Tubipora. 



Throughout this memoir I shall employ the following terms : 

 The encrusting lamina attached to stones, &c., from which the 

 young colony springs, I shall call the *' stolon." The individual 

 tubes I shall refer to as the " corallites," the laminae connecting 

 the tubes together I shall call the " platforms " (Briicke of v. 

 Koch). The inner tubes, funnel-shaped tabulae or flat tabulae, 

 in whatsoever form they occur I shall call the " tabulae."" The 

 points at which the platforms meet the corallites I shall call 

 the " nodes," and for the ciliated groove on the ventral side 

 of the stomodaeum I shall use the term I have elsewhere 

 proposed for it (8), namely, the " siphonoglyphe." 



I. The Skeleton of Tubipora. — The hard parts of the 

 *' organ-pipe coral " have already been described by several 

 authors from the time of Pallas, but as many points still 

 remain obscure and others entirely undescribed, I propose to 

 give here a further account of them from the examination of 

 a large number of different specimens belonging to different 

 species. 



In the Oxford Museum there is a specimen of a young 

 colony of Tubipora purpurea growing upon a piece of a 

 madreporarian coral. The corallites are seen to spring from 

 a flat lamina, the stolon (fig. 1, st) which, creeping over the 

 surface of the support, gives origin as it goes to new corallites 

 (fig. 1, a a). The presence of this stolon in the young colonies 

 of Tubipora seems to have been overlooked by previous 

 authors. This may be accounted for by the fact that as the 

 colony increases in size the stolon ceases to grow ; the colony, 

 however, continuing to increase in size by the origin of new 

 corallites from the platforms (fig. 1, bb), soon completely hides 

 the stolon and the area to which it is attached. Moreover, 

 when the colony dies and is broken off the stolon remains 

 attached to the rock to which it was attached, so that none of 

 the large pieces in our museums (as far as 1 have been able 



