GONIOPORA. 17 



II. THE POLYP AND ITS ANATOMY. 



All observers are in accord in describing the polyps as being very extensile. Two sets of 

 figures are given by Quoy and Gaimard.* In the form called " Gonwpora pcdunrulata " the 

 extended polyp is very tall and cylindrical with a crown of 24 tentacles alternately longer and 

 smaller. In the form called " Astrea viridis " the polyps are very large, slightly tapering, 

 and regularly constricted at intervals all the way up. The tentacles are 48 in number and 

 again alternately larger and smaller. Other figures are given by Dana and by Mr. Saville-Kent, 

 the tentacles being shown by the latter as long and tapering. Many of these differences of 

 shape are probably accidental. Another difference, evidently dependent upon the height of the 

 walls, is seen in the different degrees of retraction. In the very deep calicled forms (see 

 G. Java Sea 1, PL VIII. fig. 4) the polyp retracts deep down into the base of the pit. Quoy 

 and Gaimard descriljed the retraction in their form " G. viridis " as complete. Professor Studer, 

 on the other hand, records the inability of the polyps of his " G. columna " from Holzhafen, 

 New Ireland, to withdraw completely into their calicles. 



The tentacles are mostly 24 in number and in a single ring, but more are occasionally to 

 be found. Many of the fossil forms show by the number of the septa that they had more than 

 24, while the form " G. viridis " Q. & G. is very plainly figured with 48. A number less 

 than 24 is also common especially among the fossil forms. 



An observation of Dr. Klunzinger's requires further explanation. He describes the form 

 which he names " G. ^j/«?izt^a^a," from the Eed Sea, as having 24 tentacles in 2-3 7'o^vs. 

 If the observation was made on spirit specimens the appearance could be accounted for by 

 contraction. The " G. columna " of Dana, which Dr. Klunzinger suggested as synonymous, 

 was, as noted above, figured with a single row of tentacles. 



I know of no record of any anatomical researches into the soft parts. 



The records of colour are given in the descriptions ; they are, unfortunately, too few to be 

 of any use in the tabulation of variations given at the end of the systematic portion (Tables 

 III. ct seq.) A few examples are given by Mr. W. Saville-Kent in his ' Great Barrier 

 Eeef,' chromo plate vi. 



III. THE MORPHOLOGY OF THE SKELETON. 



Kegrets are often expressed that we possess as a rule merely the dried skeleton remains 

 of the Stony Corals. These regrets I do not share, in so far, that is, as they imply that very 

 little can be obtained from tliem. I am disposed, on the contrary, to think that with reference 

 to most of the small calicled colonies the skeletons are not only the most important parts of 

 then- organisation, but that they are parts which follow the growth of the polyps closely enough 

 to be able to register in some way or other all but the most superficial colour variations of the 



* ' Voyage de I'Astrolabe,' Atlas Zooph., xvi figs. 1-3 and 9-11. 



