FROM THE ZONE OF AMMONITES ANGULATUS. 31 



border. There are seventy-eight septa in the largest calices, and they are unequal. The 

 calices are from ^ths — ^ths inch in diameter. 



To this specific determination of M. de Fromentel the following may be added, as 

 better specimens have been derived from the Brocastle bed than elsewhere. 



The corallum is massive, and irregular in shape, but often assumes a subglobular 

 form. When this is the case there is an epitheca, which is strongly folded, but which is 

 lost as the calices are developed. 



The size of the calices is very irregular, and marginal gemmation is very 

 common. 



The septa are crowded and distinct, and in the largest calices there are many of the 

 fifth cycle, but there is great irregularity in the septal number. The septa are often not 

 quite straight, and present swellings at several points. 



Locality. Brocastle. Menetreux, near Samur. 



In the Collection of Charles Moore, Esq., F.G.S., Bath. 



2. IsastrjEA globosa, Duncan. PI. VIII, figs. 17, 18. 



The corallum is nearly spherical in shape ; it has a cylindrical but short peduncle, 

 covered with epitheca, and a rounded upper surface marked with very numerous and 

 closely placed small calices. 



The calices are shallow, faintly polygonal, and crowded with septa. The septa are 

 unequal, not very thin, and have now and then an enlargement at the inner end. The 

 smaller septa frequently unite to the lai-ger. All are very distinct. A cyclical 

 arrangement of the septa cannot be distinguished, and the septal number varies from 

 twenty, twenty-four, to thirty-six. 



There is no columella. 



The diameter of the calices is about ^^ inch. 



Locality. Brocastle. 



In the Collection of Charles Moore, Esq., F.G.S., Bath. 



The largest specimens of this fossil are usually much worn, and some care nmst 

 be taken in examining the perfect calices, for their minerahzation often suggests a 

 columella. 



