124 REPORT — 1871. 



Pocillopora, so common a genus amongst the Indo-Pacific reefs, was found 

 in the West-India Miocene, the Javan deposits, and at Turin and Dax. It 

 is considered to be allied to Ccenites by Milne-Edwards, but Jules Haime 

 doubted the Zoantharian characters of the last-named genus, which is Palae- 

 ozoic. Seriatopora, a modern genus, does not appear to have been found 

 fossil ; but it is closclj' allied, according to the received opinion, with Rhab- 

 dopora, Dendrop>ora, and Traclinpora, all Palfeozoic genera, the first being 

 Carboniferous and the others Devonian. Millepora, the great reef-building 

 genus of the West Indies, can be traced into the Lower Tertiaries, and is 

 closely allied to the Heliopora already mentioned, and by structure to the 

 Heliolites of the Palaeozoic period. 



Between the Lower Cretaceous reefs and the Palaeozoic there were the 

 Devonian, the Oolitic, the Lower Liassic, the Rhaetic, and the St. Cassian and 

 the Muschelkalk reef's, but not a trace of a tabulate coral has been recorded 

 from them, in spite of the affinities of the modern and most ancient genera 

 of the Devonian. Cyathopliora has tabulae, but its alliances are with the 

 Astraeidfe. On examining the lists published in my last Eeport, the absence 

 of tabulate corals in the whole of the Mesozoic strata of Great Britain will be 

 apparent, and I have not been able to distinguish any foreign forms belonging 

 to that vast age (except our HoJocystis eJeguns, Ed. and H.), of which notice 

 wiU be taken in treating of the Rugosa and the species of Columnastnea. 



Just as the Thecidae, Favositidas, and Halysitinac formed the reef-builders of 

 the tabulate fauna of the Palaeozoic times, so MiUeporidas and Seriatoporidae 

 contribute to the recent reef-fauna ; but these last genera had species in the 

 Palaeozoic fauna, so the break of the end of the Permian or Carboniferous 

 periods was not complete so far as the Tabulata were concerned. The ab- 

 sence of them from the successive secondary reefs that have been examined 

 by palaeontologists has probably been produced by the destructive fossilization 

 which is so common in existing reefs, and by the real absence of the forms 

 from certain reef-areas of which there is an example (see ' West-Indian Fossil 

 Corals,' Duncan). 



The Tabulata were as abundant in the Palajozoic periods as during the 

 Tertiary epochs, and the ancient and modern genera and species have certain 

 characters which differentiate them more or less from all other coral forms. 



MM. Milne-Edwards and Jules Haime characterize the Tabulata as fol- 

 lows (Hist. Nat. des Corall. iii. p. 223) : — • 



The coraUum is essentially composed of a well-developed mural system, and 

 the visceral chambers are divided into a series of stages by transverse floors, 

 which act as complete diaphragms. 



The septal apparatus is rudimentary, and is cither completely deficient or 

 only represented by trabeculae which do not extend far into the intertabular 



spaces. 



The lamellar diaphragms, floors, or tabulae, which close the visceral 

 chamber of the coraUite at difl'erent heights, diff"er from the dissepiments of 

 the Astrffiidse by not depending in any manner upon the septa, by closing 

 completely the space below, for they stretch uninterniptedly from side to 

 side, instead of simply occupying the interseptal loculi. 



The septal apparatus does not affect the Rugose type, but that character- 

 istic of the Perforata and Aporosa. The forms classified under the section of 

 the Tabulata are very numerous, and hence the importance of determining 

 whether they can be undoubtedly allied with the rest of the Actinozoa. 



Many years have elapsed since Agassiz expressed his opinion, founded upon 

 direct observation, that the Milhporce, an important genus of the Tabulata, 



