Prof. NicJwlson on Classificatio7i of "Tabulate Corals." 89 



arrived at by tlie combined observation of living and extinct 

 forms, indicating the groups into which the so-called " Tabu- 

 late Corals " may be divided, with the structure and zoolo- 

 gical affinities of these groups, so far as at present known. 



The "Tabulata," as originally understood, constitute one 

 of the four primary divisions of the Zoantharian Adinozoa, as 

 laid down and defined by Milne-Edwards and Haime in their 

 great works on the fossil corals (Brit. Foss. Cor., Intro., 1850, 

 and Pol. Foss. des Terr. Pal, 1851). The distinguished 

 authorities just mentioned included under the name " Tabu- 

 lata" a large number of corals, ranging from the Silurian 

 period to the present day, and often of very different struc- 

 ture, but characterised by the possession of well-developed 

 " walls," by the fact that the visceral chambers of the coral- 

 lites are traversed by horizontal partitions or " tabulse," and 

 by the rudimentary condition of the septa. Of these char- 

 acters the essential one is the division of the cavities of the 

 coralUtes into successive storeys by means of "tabuhe" or 

 transverse plates, since the walls are often more or less 

 largely perforate, and the condition of the septa is quite a 

 secondary matter. Milne-Edwards and Haime divide the 

 " Tabulata " as follows : 



Family 1. Millepoeid^. — CoraUum principally composed 

 of a very abundant coenenchyma, distinct from the w^alls of 

 the corallites, and of a tubular or cellular structure. Septa 

 not numerous ; tabulae numerous and well formed. Genera 

 — Millepora,'Ldi'm.', Heliopora, J)q Blainv.: Ildiolites, Dsma, ; 

 Flasmopora, E. and H.; Fistnlipora, M'Coy; Fropora^ E. 

 and H. ; Axopora, E. and H. ; and Zohopora, E. and H. 



Family II. Favositid^. — Corallum essentially formed by 

 lamellar walls, with little or no coenenchyma. Visceral 

 chambers divided by numerous and well-developed complete 

 tabulae. 



Tribe 1. Favositince. — Corallum massive; walls perforated; 

 septa rudimentary; no coenenchyma. Genera — Favosites, 

 Lam.; 3fichelinia, De Kon.; Koninckia, E. and H.; and 

 Alveolites, Lam. 

 Tribe 2. Chcetetince. — Corallum massive ; w^aUs not per- 

 forated; neither septa nor coenenchyma. Genera — 



