Frof. Nicholson on Classification of " TahUate Corals." 97 



lites, which possess well-developed walls. The walls are, 

 however, perforated by a larger or smaller number of rounded 

 apertures — the "mural pores" — which place the visceral 

 chambers of neighbouring corallites in direct communication. 

 There is no ccenenchyma; the septa are usually spiniform, 

 sometimes obsolete, rarely lamellar; and the tabulse are 

 numerous and usually complete. 



After an extended study of the minute structure of the 

 Favositidw, I cannot doubt that Professor Verrill and Dr 

 Lindstrom are correct in referring the family to the Zoan- 

 tharia perforata. I also recognise the numerous points of 

 resemblance between the Favositidm and the Poritidoe, but I 

 cannot follow the above-mentioned high authorities in re- 

 garding the present group as a mere sub-family of the Pori- 

 tidce. On the contrary, I believe that the Favositidce, as 

 here understood, embraces a large number of types (mostly 

 Palaeozoic), all of which are more or less closely allied to the 

 Poriiidce, and some of which are perhaps undistinguishable 

 from the latter family, but which really represent a series of 

 separate but allied groups. 



The Favositidce constitute by far the largest and the most 

 important group of the so-called " Tabulata," and it is quite 

 impossible that I should discuss here, even in the briefest 

 manner, the different types which belong to the family. I 

 can, therefore, only content myself by subjoining here a list 

 of the genera which I believe to properly belong to this 

 great family, and I have no doubt that future discoveries 

 will show that this table must be enlarged : 



Genus. Geological Eange. 



Favosites, Lam., . . . Silurian to Carboniferous. 

 Alveolites, Lam., . . . Silurian to Devonian. 

 Vermipora, Hall, . . Silurian to Devonian. 



C Upper Silurian ?, Devonian, 

 Michelinia, De Kon., . . < and Carboniferous (perhaps 



( =Pleurodictyum, Goldf). 

 Pletcr odictyicm, Goldl, . . Upper Silurian ? and Devonian. 

 ChonosUffites. E. and H. ) Devonian. 



{—Haimeophyllunfi, Bill.), ) 

 Pachypora, Lindstrom, . . Upper Silurian and Devonian. 

 VOL. v. G 



