302 ZOANTHARIA. 



strata of this age in Europe. It may be noted in connection with Calceola 

 sa?idalina that the internal structure of the curious Cystiphyllum lamel- 

 losimi of the same geological horizon exhibits, in its young stages, a curious 

 resemblance to that of the present form, the latter, however, not being 

 known to possess an operculum. This fact, along with the general 

 identity in structure between Arceopoma prismaticum and the typical 

 Cystiphylla, may be taken as fully corroborating Lindstrom's conclusion 

 that these remarkable Operculate Corals cannot be separated from the 

 Madreporaria Rugosa. 



