62 BRITISH FOSSIL CORALS. 



C. cylindrical, C. Breda, and C.Koninckii, have only six large pali, whereas in C. Bowerbankii 

 the number of these organs amounts to twelve. C. laevigata 1 differs from the above- 

 described species, by the pali being narrow, and very thick, and C. Debeyana by the 

 existence of a well-marked epithecal band near the calice. 



M. Alcide d'Orbigny has, in a recent publication, 2 referred to this species as the type 

 of his new genus Amblocyathus, which he defines as being Cyathina, with a circular calice 

 and a round columella. He acids that Amblocyathus is a lost genus, and contains three 

 fossil species belonging to the Neocomian and Albian 3 strata. We must, however, beg 

 leave to remark, that the two above-mentioned characters are met with in almost every 

 species of our Cyathina, and most especially in C. cyathus, which is the type of the genus 

 Cyathina, and is actually living in the Mediterranean sea. Only two of the species 

 referred to the genus Cyathina in our ' Monograph of the Turbinolidae' present a slightly 

 oval calice and a transversal columella — C. pseudoturbinolia and C. Guadulpensis. In 

 C. Smithii the columella is oblong, but the calice is circular, or nearly so. If it be con. 

 sidered necessary to separate the Cyathina with a circular calice from those that have an 

 oval calice, it would therefore be more proper to give a new generic name to the latter, and 

 not to change the denomination of the group containing the very species for which 

 Ehrenberg first established the genus Cyathina. But this innovation, proposed by 

 M. d'Orbigny, appears to us as being in every respect unnecessary, for the slight deformation 

 of the calice and the columella which forms the sole basis of the new generic division, can 

 hardly be considered as characters of sufficient value ; species that differ in no other 

 respect are often found to vary in this way, and even specimens belonging to the same 

 species sometimes differ much in the form of the calicular margin. Thus, although the 

 calice is circular, or nearly so, in most specimens of C. cyathus and C. Smithii that are met 

 with, we have seen some that were compressed, and had the calice as oval as in C. pseudo- 

 turbinolia and C. Guadulpensis ; similar deviations from the normal form are also to be 

 met with in the columella; in C. Smithii, for example, this organ is sometimes quite 

 circular, although it is in general oblong. Differences of this kind, when not more marked 

 than is the case among the various species of Cyathina, can therefore scarcely be deemed 

 important enough to characterise generic divisions ; and, as in the present case, they do 

 not appear to coexist with any other structural peculiarity, we see no reason for admitting 

 the new genus Amblocyathus. 



1 Tab. ix, fig. I. 



2 Note sur des Polypiers Fossiles, Paris, 1849. 



3 M. d'Orbigny employs the name of Albian formation to designate tbe Gault. 



