of the Organ-pipe Coral. 370 



perhaps there may always be some doubt as to which species 

 is entitled to be called musica ; but as the Linnean species 

 came from the Indian Ocean, I think I may fairly assume 

 that the Seychelles species is the Tubipora musica, Linn., the 

 Halcyonium rubrum indicum of Humphius ; and if so, I can- 

 not find that the polyps have hitherto been dissected. In 

 Prof. Kolliker's short notes on " Polymorphism in various 

 Genera of Alcyonaria"*,he mentions having examined a species 

 of Tubipora from the Viti archipelago, which had been pre- 

 served in spirits. The species is not mentioned, but is pro- 

 bably one of the two species described by Dana as from the 

 Fiji or Viti Islands, both of which differ specifically, as I take 

 it, from the Indian-Ocean species. 



The polyp consists of eight pinnate tentacles, each tentacle 

 with from fifteen to seventeen pinnae on either side ; these 

 tentacles are thickly studded with spicules of an oval shape, 

 flat, somewhat longer than broad ; they closely resemble the 

 lenticular spicules of Kolliker : they are met with all over 

 the tentacle, down the centre of which there is one compact 

 row, forming as it were a midrib ; they are often slightly 

 compressed in the centre, so as to form a figure of eight. In 

 the centre of the tentacles is the mouth, with a slightly raised 

 circular lip. When the polyp is alarmed, the tentacles are 

 first closed together, and then the polyp sinks down quite 

 into the tube ; as it becomes more completely retracted, it 

 draws in after it the uppermost portion of the tube itself, in- 

 verting this and folding it in, until the open mouth of the 

 tube is thereby completely filled. It is, of course, only the yet 

 spicular, and not the solid portion of the tube that is thus in- 

 verted ; and the folds thus formed equal in number the tenta- 

 cles. I have more than once traced these spicular portions up 

 to the very base of the tentacles, where the fusiform spicules 

 end and the characteristic tentacle- and body-spicules commence, 

 these spicules thus forming a series of triangular spaces, the 

 bases of which join on with the hardened edge of the tube, 

 and the apices are situated at the base of each tentacle. The 

 spicules secreted by this portion of the ectodermic layer are of 

 several sorts : — First, the warty fusiform spicule, so commonly 

 met with in the Alcyonidas ; these spicules will be found in 

 all stages of growth and of coalescence : thus at the upper 

 portion of the edge of the tube, where it is non-retractile, the 

 calcareous tissue will be found to consist of a series of them, 

 partially joined together and making a kind of coarse open net- 

 work (fig. 10), which, on being macerated in caustic potash, does 



* Verhandl. d. phys.-med. Gesellschaft in Wiirzburg, Dec. 28, 1867, and 

 Zoological Record for 1867, p. 661. 



