66 TABULATE CORALS. 



must again draw attention to the fact that Messrs Milne- 

 Edwards and Haime have figured (Brit. Foss. Cor., PL LX., 

 fig. 2/) a specimen of F. Forbesi from the Upper Silurian, in 

 which structures of apparently precisely the same nature seem 

 to be present. Upon the whole, therefore, I do not think that 

 the structures in question can be regarded as of specific value, 

 though they constitute a very striking feature in the Devonian 

 variety now under consideration. 



Of the other characters of the present form, it is only neces- 

 sary to allude to two. In the first place, the mural pores have 

 the character, which seems to be the general rule in the less 

 aberrant types of F. Forbesi, that they are usually biserial, 

 though sometimes triserial. They are more closely set than 

 in F. Gothlandica, and are stated by Dr Rominger to be sur- 

 rounded by a depression instead of an elevated ring. In the 

 second place, many of the calices in the lower part of the coral- 

 lum become covered and completely sealed up by an epithecal 

 or opercular membrane, which can hardly be regarded as the 

 result of mere age, since it seems to be present in extremely 

 young examples (PI. III., fig. 2). It is, however, most con- 

 spicuous in the old specimens, in which a variable number of 

 the corallites are always, or almost always, closed in this way 

 (PI. III., fig. 2 a), those at the summit of the colony remaining 

 open. It must be admitted that this peculiarity has not been 

 observed in any of the Silurian examples of F. Forbesi; but as 

 it occurs in several of the other species of Favosites in the same 

 deposits, I do not think that it can well be regarded as a 

 character of specific importance, being rather the result of local 

 conditions and of environment. 



Formation and Locality. (i.) The typical form of F. Forbesi 

 Wenlock Limestone, Longhope, Dudley, Benthall Edge, and 

 Stoke-Edith ; Wenlock Limestone, Gotland. 



(2.) F. Forbesi, var. Waldronensis Niagara Limestone, 

 Waldron, Indiana, U.S. 



(3.) F. Forbesi, var. Eifelensis Devonian (Eifler-kalk), 

 Gerolstein, Eifel. 



