70 BRITISH FOSSIL CORALS. 



CHAPTER VII. 



CORALS FROM THE LOWER GREEN SAND. 



The remains of true Polypi are very rare in this part of the British geological strata ; 

 the fossil which Mr. Lonsdale has lately described under the name of CJioristopetalum imparl 

 and which was found in the lower greensand at Atherfield, does not appear to us to 

 belong to this class, and is, in our opinion, a Bryozoon. We have as yet met with but 

 one species of Zoantharia, which can be referred with any degree of certainty to this 

 formation. 



Family STAURLDJE (p. lxiv). 



Genus, Holoctstis (p. lxiv). 

 Holocystis elegans. Tab. X, fig. 5, 5 a, 5 b. 



Astrea, Fitton, On the Strata below the Chalk, in Geol. Trans., s. 2, vol. iv, p. 352, 1843. 

 Astbea elegans, Fitton, in Quarterly Journ. Geol. Soc, vol. iii, p. 296, 1847. 

 Cyathophora (?) elegans, Lonsdale, Proceed, of the Geol. Soc., vol. v, part i, p. 83, tab. iv, 



fig. 12, 15, 1849. 



Corallum complex, astreiform, constituting a convex mass, and augmenting by extra 

 calicular gemmation ; the young individuals being produced at the point of junction of the 

 surrounding calices. Corattites somewhat prismatic, and cemented together laterally, 

 either by the direct union of their walls, or by means of the costse, which are thick, and in 

 general pretty well developed. Calices subpolygonal, separated in general by a simple but 

 thick mural ridge ; sometimes by walls that remain distinct, and are in their turn separated 

 by a small intermural furrow. Fossida deep. Columella very small, and appearing to be 

 styliform. Septa forming three complete cycla, and four well-characterised systems. The 

 four primary ones much more developed than the others, reaching almost to the centre of 

 the fossula, and giving to the calice a crucial character, which is never met with in Astreidte, 

 Oculinidse, Turbinolidas, &c. The septa are slightly exsert, closely set, thick exteriorly, 

 and very slightly granulated laterally ; they appear to have undivided edges, and they 

 differ much in size, according to the cycla to which they belong. The interseptal dissepiments 

 are simple, horizontal, or slightly convex, and placed at the same level in the different loculi, 



1 Proceedings of the Geol. Soc, vol. v, part i, p. 69, tab. iv, figs. 5 to 11, 1849. 



