382 On the Animal of the Organ-pipe Coral. 



height of its tube ; or, in other words, the spicules are being 

 constantly consolidated into the tube, and the tube thus in- 

 creases in height. In some cases I have been able to trace the 

 mesenteric bands, which attach the lower portion of the body 

 of the polyp to the walls of the skeleton-tube, as far as the 

 second external septum in depth ; and it is very evident that 

 as the outer walls of the tube become consolidated, not only 

 does the tube become elongated, but the polyp elevates itself 

 at the same time in the tube. 



I am inclined, with Milne-Edwards, to regard the genus 

 Tubipora as belonging to the first family of the order Alcyo- 

 naria, viz. Alcyonidffi, but would place it as a separate section 

 of the subfamily Alcyoninae. Thus we should have — 



Order ALCYONARIA. 

 Family 1. Alcyonidse. 



Subfamily 1. Cornulaminje. 



„ 2. Alcyoninjz ; and, dividing this into three 



sections, as follows : — 



Alcyoninm. 



(i.) Naked or soft, as Alcyoninm. 

 (ii.) Armed with large spicules, as Nephthya. 

 (in.) Tubed ; tubes formed of coalesced spicules, as 

 in Tubipora. 



Some may perhaps consider it advisable to give more weight 

 to the great difference in the calcareous secretions, and place 

 the genus in a subfamily to rank as a third subfamily of the 

 Alcyonidfe, called Tubiporinse, which would be characterized 

 by having lenticular spicules developed in the tentacles, the 

 fusiform spicules of the outer body -layer forming dense hard 

 tubes united to each other by calcareous septa. 



EXPLANATION OF PLATE XXIII. 



Fig. 1. Mass of Tubipora musica, nat. size. 



Fig. 2. The same, to show the buds. 



Fig. 3. Polyps, seen from above, three expanded ; from the side of the 

 retracted polyp which is seen in the lower part of the figure, 

 between the two expanded polyps, will be found the lateral 

 fold-like prolongation of the tube referred to in the text. 



Fig. 4. Polyps in different stages of expansion and retraction : at e the 

 lateral fold-like prolongation is seen. 



Fig. 5. Mouth, with circular lip and four tentacles studded with spicules. 



Fig. 6. A section through tube and polyp, the latter fully retracted. 



Fig. 7. Lenticular spicules from the tentacles. 



