18 



BRITISH FOSSIL CORALS 



There are four cycles of septa iu six systems. The primary reach the columella. The 

 tertiary, which are longer than those of the higher orders, join the secondary septa. 



The columella is well defined, and is circular in its transverse outline. 



The diameter of the corallite is about i inch. 



The specimens are usually covered with parasitic corals or sponges. 



Locality. The Sutton Stone. The St. Cassian beds. In the Museum of Practical 

 Geology, London. 



Laube's^ description of this species is very faithful, and it is readily recognised by 

 the curious septal arrangement. The specimens are rare in the Sutton Stone, and 

 the sections showing the septa require very careful examination before they can be 

 understood. 



Family— ASTR^EACEyE. 

 Genus — Astroccenia. 



1. AsTROCffixiA GiBBOSA, Duncaii. PI. V, figs. 2, 3, 4, 12; PI. IV, fig. 3; PI. VI, 

 figs. 1, 2, 3, 4. 



The corallum is large, and covered with rounded eminences of various sizes. 

 The calices are large, polygonal, close, irregularly placed, irregular in size, and 

 shallow. 



The septa are usually twenty in number, are joined to small narrow club-shaped 

 straight costse, are very unequal in size, and usually one half of them reach to the 

 columella. The smaller and shorter septa unite in many instances to the larger septum 

 between them, but not very close to the columella. The septa are finely dentate laterally, 

 and there is a trace iu some of the longest of a swelling close to the columella. Their 

 development is very irregular. 



The columella is moderately prominent and large. 



The ccenenchyma is not strongly developed, but in sections the presence of orna- 

 mentation in the form of round processes is observable. The endotheca is occasionally 

 noticed in the calicular fossa, and extends from septum to septum. 



Three large calices, with their ccenenchyma, occupy the length of nearly y'tlis inch. 



Locality. The Sutton Stone, and Brocastle. 



In the Museum of Practical Geology, London ; and in the Collections of Charles Moore, 

 Ebq., F.G.S., and Rev. W. Winwood, F.G.S., Bath. 



' Laube, op. cit. 



