44 TABULATE CORALS. 



Alveolites altogether, as including types of very different 

 affinities ; but the name may be advantageously retained, in the 

 meanwhile at any rate, for forms like A. suborbicularis. Lam.; 

 though it is difficult to point to any characters which definitely 

 separate these from Favosites except their inclined corallites and 

 oblique calices. Pachypora and Striatopora^ again, are hardly 

 separable from the dendroid forms of Favosites by anything 

 else except by the thickening of the walls of the corallites near 

 their mouths; and, in fact, even this distinction would fail 

 unless we remove from the latter category, as will here be 

 done, some forms which are usually included in it (such as 

 F. cristata, E. and H., and F. cervicornis, De Blainv.) The 

 position of Cladopora, Hall, I shall consider in dealing with 

 Pachypora. Fistulipora, M'Coy, can in general be readily dis- 

 tinguished from Favosites, both by the existence of two distinct 

 series of corallites, and by the absence in the former of mural 

 pores. There is, however, one species — viz., Favosites {Fistu- 

 lipora) Canadensis, Bill., from the Devonian of Canada, which 

 ordinarily has all the external features of Fistulipora, but which 

 has been shown by Rominger to possess the mural pores of 

 Favosites, a fact which I can corroborate from an examination 

 of microscopic sections. Moreover, this transitional form some- 

 times loses the characteristic of possessing a series of large 

 corallites interspersed among numerous smaller ones, and 

 passes by insensible gradations into a type so similar to the 

 ordinary examples of Favosites, that it has been separated by 

 Dr Rominger, as I think without sufficient reason, to constitute 

 a new species under the name of F. placenta (Foss. Cor. of 

 Michigan, p. 32). 



Michelinia, De Kon., is another close ally of Favosites, for 

 I am unable to agree with Dr Lindstrom in thinking that there 

 is any essential difference in the nature of the mural pores in 

 these two genera (On the Affinities of the Anthozoa Tabulata, 

 Ann. and Mag. Nat. Hist., sen 4, vol. xviii. p. 12). It differs 

 from Favosites almost exclusively in the complex character of 

 its tabulae. 



