ADDENDUM TO THE ANTHOZOA 79 



79. Milne-Edwards, H., and Haime. Hist. Nat. des Coralliaires, Paris, 1857, 



3 vols. 



80. Moseley, H. N. Phil. Trans, clxvi. 1876, p. 91. (Heliopora and Sarco- 



phytum.) 



81. Ibid. Quart. Jour. Micr. Sci. xxii. 1882. (Seriatopora, Pocillopora.) 



82. Ibid. Challenger Reports, Zool. ii. 1881. (Deep Sea Corals.) 



83. Niclwlson, H. A. Palaeozoic Tabulate Corals, Edinb. 1879. 



84. Ibid. The Genus Monticulipora, Edinb. 1881. 



84a. Ogilvie, M. M. Phil. Trans, clxxxvii. 1896, p. 83. 



85. Ortmann, A. Zeit. Wiss. Zool. 1. 1890, p. 278. (Formation of Colonies in 



Madreporaria. ) 



85a. Pratz, K Palaeontographica, xxix. 1882. (Structure and Relationships of 

 Extinct Corals.) 



86. Quclch, J. J. Challenger Reports, Zool. xvi. 1886. (Reef Corals. ) 



87. Quo]) and Gaimard. Voyage de 1' Astrolabe, 1834. 



88. Ridley, S. 0. Rep. Zool. Collect. H.M.S. Alert, Alcyonaria, p. 356. 



89. Sars, M. Fauna littoralis Norvegiae, 1846, p. 28. (Arachnactis.) 



90. Schneider and Rotteken. Ann. Mag. Nat. Hist. (4), vii. 1871, p. 437. 



(Transl.) 



91. Semper, C. Zeit. Wiss. Zool. xxii. 1872, p. 235. (Alternation of Generations 



in Corals.) 



92. Stitder, Th\ Monatsb. d. k. Preuss. Akad. Wiss. 1875, p. 668. (Soleno- 



caulon.) 



93. Stutchbury. Trans. Linn. Soc. 1830, p. 494. (Asexual Reproduction of 



Fungia. ) 



94. Verrill. Amer. Jour. Arts and Sciences, xlv. 1868, p. 415 ; and numerous 



papers in succeeding numbers. 



95. Vogt, C. Arch, de Biologic, viii. 1888. (Cerianthus.) 



96. Wilson, E. B. Phil. Trans, clxxir. 1883, p. 723. (Develpt. of Renilla.) 



97. Ibid. Mitth. Zool. Stat. Neapel. v. 1884, p. 1. (Mesenterial Filaments of 



Alcyonaria.) 



98. Wilson, H. V. Journal of Morphology, ii. 1888, p. 191. (Develpt. of 



Manicina.) 



99. Wright, P. S. Proc. Roy. Phys. Soc. Edinb. ii. 1859, p. 91. (Peachia.) 



100. Ibid. Quart. Jour. Micros. Sci. v. 1865, p. 213. (Hartea.) 



101. WrigU, P. S., and Studer, Th. Challenger Reports, Zoology, xxxi. 



(Alcyonaria), 1889. 



ADDENDUM. 



Since this article was written, the author has studied the structure and 

 formation of the calcareous skeleton in a number of different genera of 

 Anthozoa with the view of deciding the question whether the skeleton of 

 the Scleractiniae is composed of entoplastic spicules as von Heider and 

 Ogilvie assert, or whether it is an ectoplastic product as described by von 

 Koch. The results of these investigations may be briefly summed up as 

 follows : In all the Alcyonaria except Heliopora the calcareous skeleton 

 consists of spicules, a " spicule " being the entoplastic product of a single 

 cell or of a coenocyte. The spicule is covered by a sheath of organic 

 substance, and its axis is traversed by an organic thread or bundle of 

 threads from which other organic threads radiate outwards and are 



