Actinozoan Nature o/Millepora alclcornls. 357 



trusts toobtain results at tlie Sandwich Islands*. This difficulty 

 is again referred to (p. 63) ; but some information is given regard- 

 ing the question : — " The calcareous coenenchymal tissue of 

 Millepora differs extremely from that of Heliopora in being 

 reticulate, not tubular : in histological structure it is similar to 

 Heliopora. The coral has only a thin superficial layer of soft 

 living tissue, composed of a network of canals filled with cells 

 resembling those of the canals of Alcyonarians, and covered 

 externally with nematocysts." ..." Two kinds of polyps are 

 present, large and small. Tentacles are present in both kinds ; 

 they appear to be four in number and compound. They are 

 simply retracted by means of muscular fibres, which are ar- 

 ranged round the base of the cylindrical stomach radially, but, 

 as far as has yet been seen, without any disposition in definite 

 groups. No mesenteries have been seen." 



Further on the author notices that ^^ Heliopora is most un- 

 doubtedly an Alcyonarian. The number of its mesenteries, 

 the distribution with regard to them of the retractor muscles, and 

 the form and number of its tentacles are decisive evidence in 

 the matter." Yet in a few lines, in spite of what the author 

 had written regarding the similarity of their histological cha- 

 racters, we are told that with the Milleporidge and with the 

 Pocilloporidae and Seriatoporidai, Heliopora is allied solely 

 on account of its possession of tabulas. Mr. Moseley had 

 Prof. Verrill's book to refer to, and yet appears to have for- 

 gotten Mr. Bradley's work, which his own researches prove to 

 be correct. 



Evidently in extreme perplexity, like most of us who have 

 ventured to touch the subject of the Millepores, Mr. Moseley 

 determines that " no certain conclusion can be arrived at from 

 the few facts yet ascertained." In other words, the question 

 of the structure and affinities is perfectly open. 



Many years ago one of us, then Lieut. Nelson, R.E., was 

 quartered at Bermuda ; and the geological description of the 

 Islands in the ' Transactions of the Geological Society ' f was 

 one of the results of some study there. The structure of 

 Millepora alcicornis was also made a study, and drawings were 



* Proc. Royal Soc. vol. xxiv. no. 164, p. 60. The author remarks : — 

 " Few original works relating to the subjects treated of in this paper were 

 available for reference on board the 'Challenger.'" We suppose that the 

 whole of the writings of one of us regarding the Rugosa, in the ' Phil. 

 Trans.,' the Palseontographical Society's publications (Secondary Corals), 

 the papers on Australian corals, and the reports on the Tabulata and 

 Rugosa were not there. In explaining his views regarding the Rugosa 

 the author simply mistakes our meaning in relation to the origin of that 

 group. 



t " On the Geology of the Beinnudas," Trans. Geol. Soc. 1834, 2nd ser, 

 vol. V. p. 10.S. 



