of till' AittJmzoti Tnhuhitit. 13 



of a Ilah/sites, the great accordance in tliiir intimate structure 

 is very striking. In both there arc the hirgo-sizecl corallitea, 

 and between these a more or less dense ca-nenehyma of narrow 

 tabuhite tulK-s. 'I'his structure (the " Zwischenwiinde " of 

 Fiseher-lienzcMi, in his ])aper " Ueber llalusiies^^^ ]>. 12) is of 

 a very variable nature both in Ilahfsites and in the lleliolitidaj. 

 Longitudinal sections of P/asnioj>ora [Prajwra) tuhnlata and 

 Hdli/sites cafe/iK /arias resemble each other most; but there 

 is also a great similarity iti the initial stages of growth in both 

 genera. In all the lleliolitida*, as well as in FavositeSy S^rin- 

 gopora^ &c., the earliest stage of growth is that of a small, 

 narrow, conical polypary atKxed to some other fossil along its 

 whole length. In Favosites and several other corals, new 

 corallites bud out immediately from the inferior lip of the first 

 corallite. In Jleliolites and Ilali/sites^ again, there is first 

 formed the ccenenchyma, as an excrescence of the calicular 

 rim, all around it ; and out of this ccenenchyma the new coral- 

 lites are developed. The difference between the further growth 

 in these last-mentioned genera is only that in Ileliolites the 

 new corallites group themselves around their parent ; whilst in 

 Hall/sites they range themselves in a line, each new^ one at the 

 side of its predecessor. Both genera agree also in having, as 

 a rule, twelve septa, which are subject to great variations in 

 size in different corallites, being always of the same size in 

 the same corallite. In some species the septa meet centrally 

 and form a kind of columella, which is elevated and styliform 

 in HelioUtcs — but in other forms is alone present, the septa 

 having almost disappeared. Where the corallites are large 

 the septa are generally small or quite deficient, as in HelioUtes 

 megastortia and Ilalysites catenularias. In those species, again, 

 which have small corallites, as Halysites escharoides and 

 HelioUtes inordinatus^ the septa are proportionally more 

 developed. I, then, consider Holy sites to be a member of the 

 Heliolitida? ; and it is not improbable that Thecia, with its 

 twelve septa and dense tubular ccenenchyma, also belongs to 

 the same family. Amongst recent corals Pocillopora most 

 closely resembles the Heliolitidie. 



The genus Battershyia I have not seen ; but it has been 

 shown by Duncan (Trans. Roy. Soc. 1867, p. 648) to be one 

 of the Astraiidte. 



Columnaria (or Favistella, which has the priority) is one 

 of the Cyathophyllida?, as may be seen by its gemmation. 



Fletcherin, represented only by F. tubifera, E. & II., seema 

 to be a Cystiphylloid of very variable characters. In the 

 smaller varieties the vesicidar endotheca has been converted 

 into tabuhv, and the septa have almost disappeared. 



