CLASSIFICA TION. 9 



referred, as is also probably correct, to the Perforate Corals, 

 and is regarded as a sub-family of the Poritidce, Koninckia 

 being removed from it, and placed with Alveopora in another 

 sub-family (the AlveopoiHncE) of the same group ; Syringopoi^a, 

 A^ilopora, Halysites, and their allies, are placed (without suffi- 

 cient reasons adduced) among the Alcyonaria, in, the family of 

 the Tubiporidis ; and the Chcetetidce are entirely excluded from 

 the Actinosoa, being presumably regarded as truly belonging 

 to the Polyzoa. 



The preceding historical sketch is necessarily extremely 

 brief and imperfect, the limited space at my disposal not allow- 

 ing it to be otherwise ; but it will be sufficient to show the 

 principal tendencies of the more recent researches of naturalists 

 and palaeontologists with regard to the old group of the " Tab- 

 ulate Corals." These researches, though still incomplete, are 

 so far advanced that the abandonment of the "Tabtdata" as a 

 distinct group of the Zoantharia can hardly be avoided ; while 

 the removal elsewhere of some of the principal forms previously 

 included under this head is already a fact accomplished. It is, 

 indeed, now quite clear that the chief character relied upon by 

 Milne-Edwards and Haime, in their definition of the "Tabti- 

 lata" — namely, the presence of "tabulae" — is one of very 

 limited classificatory value. Thus, tabula: occur in Pocillo- 

 t>ora, Cyathophora, Coslastraa, ClaiLsastrcea, and occasionally 

 in Lophohelia, among the Zoantharia Aporosa ; in Alveopora, 

 and the allied Favositipora, among the recent Zoantharia Per- 

 forata; in Heliopora and its allies, in the Alcyonaria, as well 

 as occasionally in TiMpora ; in the great majority of the 

 Rucrose Corals ; in Millepora and its allies among the Hydro- 

 zoa; and lastly, in a few extinct types of the Polyzoa {e.g., 

 Radiopora and Heterodictya). The mere fact of the occurrence 

 of tabula; in so many forms of such diverse zoological affinities, 

 is sufficient proof that these structures cannot be used in form- 

 ing a classification of the Corals; but it is at the same time con- 

 clusive that the "tabulae" of these different types, though undis- 

 tincruishable in appearance and performing identical functions. 



