REPORT ON CORALS — HELIOPORID.E. TJ5 



more marked, aud the corallum appears as if formed of a scries of calicles fitted one 

 within another. The discovery by Mr Charles Stewart 1 of the existence in Tubipora 

 musica of infundibuliform tabulae, which form delicate axial tubes within the larger 

 tubes of the corallum just as in Syringopora, seems to prove undoubtedly that Dana, 

 Haeckel, Zittel, and others are quite correct in placing these fossil forms in near relation 

 with Tubipora. Professor Alleyne Nicholson, 2 who disagrees with the conclusions of 

 the above-named authors, and considers Syringopora to be allied to the Zoantharia 

 perforata, is apparently unaware of Mr Stewart's observations. He gives some account 

 of the genus Syringolites (Hinde) which, though it has polygonal contiguous coralites, 

 with mural pores like Favosites, has also infundibuliform tabulae, and even axial 

 tubes like Syringopora. This link closely connecting Favosites and Tubipora through 

 Syringopora is a further proof of the Alcyonarian affinities of Favosites and its 

 other allies. 



On the Septa of Heliopora. — A difficulty appears to arise from the peculiar mode of 

 the development of the calicles by budding in Heliopora, the foldings of the walls of the 

 calicles being due, to a considerable extent at least, to the formation of these walls from 

 a circle of ccenenchymal tubes. The septa are, however, not entirely formed in this way. 

 It would of course be of great interest to see whether the primitive calicle, in the develop- 

 ing Heliopora colony, forms calcareous septa. 



Heliopora having so commonly twelve septa, and in conjunction with these eight 

 mesenteries, it was at first thought that here some key would be found to the elucidation 

 of the question of the relations of the tetrameral corals to the Hexactinians ; but no 

 definite arrangement of the eight mesenteries to the twelve septa could be discovered. 



Zooids of Sarcophyton compared with those of Pennatulids. — With regard to Sarco- 

 phyton, the fact that its colonies are composed of multitudes of siphonozooids, combined 

 with a lesser number of sexual autozooids, as amongst the Pennatulidae, was discovered 

 by Kolliker, who failed to find such a condition existing in any other member of the 

 Alcyonidae or Gorgonidse. Tn Sarcophyton and in Heliopora the " Dorsalfacher " 

 are all turned towards the axes of the colonies and directed upwards, just as in 

 Pennatulidae. The siphonozooids in their structure seem to conform very closely to 

 those of Pennatulids (Sarcophyllum, e.g.); but to the list of distinctive differences 

 between the siphonozooids and autozooids of Pennatulids given by Kolliker, viz., the 

 absence in the siphonozooids of tentacles, the presence of two mesenterial filaments (the 

 dorsal ones), the absence of generative organs, and the shortening of the hypogastric 

 region to such an extent that it fuses with the anastomosing canal system — to these 

 marks of distinction must be added, in the case of the siphonozooids of Sarcophyton, the 

 fact that four of the mesenteries, the dorsal and ventral pairs, are deeper than the others. 



1 C. Stewart, F.L.S., On a New Species of Stylaster, with a Note on Tuhijmra, Jour, of the Micro. Sci., 1879. 

 - H. Alleyne Nicholson, I.e., pp. 18, 19, 214. 



