6o TABULATE CORALS. 



vertical sections, and tlie British examples of this species, so 

 far as I have seen, very seldom exhibit the interior of the 

 tubes. Finally, for the reason just given, I am not certain 

 as to the arrangement of the mural pores in F. Foi'-besi ; but 

 in such vertical sections as show these apertures at all, they ap- 

 pear to be biserial or triserial, alternating in contiguous rows, 

 and more closely set than in F. Gothlandica (PI. II., fig. i a). 



Favosites Forbesi, E. and H., var. Waldronensis, Nich. 



(PI. II., figs. 2-2 b.) 



Favosites Forbesi (?), Hall, Twenty-eighth Rep. on the State Cabinet of N.Y., 



PI. IV., figs. 6-15. 



Corallum forming globular or pyriform masses (PI. II., 2), 

 varying from half an inch up to two inches or more in diameter, 

 and attached by a broad peduncle, the lower part of which may 

 be covered by an epitheca. Large corallites, varying from one 

 and a half to two lines in diameter, and proportionately very 

 numerous, the small corallites occupying the angular spaces 

 between the former, and varying from a fiftieth of an inch to 

 more than half a line in diameter. Septa apparently obsolete 

 (PI. II., 2 a). Tabulee numerous, thin, horizontal, usually about 

 seven in the space of two lines (PI. II., 2 b). 



This well-marked form, from the Niagara Limestone of 

 Waldron, Indiana, quite resembles the common F. Forbesi of 

 the corresponding Wenlock Limestone of Europe in all essen- 

 tial features ; and it would be difficult or impossible to mention 

 any characters by which young specimens of these two forms 

 (up to half an inch or rather more in diameter) could be 

 separated from one another. The chief peculiarity of the 

 present variety lies in the fact that it preserves in its adult 

 condition the distinctions which characterise the young both of 

 itself and of the normal form of F. Forbesi. Hence the fully- 

 grown F. Forbesi, var. Waldronensis, is at once separated by 

 its numerous and exceptionally large corallites, and the com- 

 parative paucity of the small tubes, from the adult F. Forbesi 

 of the British Wenlock, in which the large tubes are much 



