CORALS FROM THE GAULT. 63 



2. Genus Cyclocyathus (p. xiv). 



Cyclocyathus Fittoni. Tab. XI, fig. 3, 3 a, 3 b. 



Corallum simple, discoidal, short ; mural disc horizontal, or slightly concave, and pre- 

 senting in its centre a small, irregular cicatrix, indicative of its primitive adherence. 

 Epitheca very thin, presenting some slight concentric striae, and not preventing the radiate 

 costae from being visible. These are straight, and not very prominent ; but those of the 

 first and second order are well marked. The edge, of the mural disc is thin, and slightly 

 prominent. The upper or calicular mrface of the corallum is rather convex externally, 

 and concave towards the centre. The fossula is shallow, but large, and well marked. 

 Columella fasciculate, well developed, and terminated by a broad, papillose surface. Septa 

 forming four complete cycla. The six fundamental septal systems distinct, but the septa 

 of the second order not differing much from those of the first order. AJ1 the septa well 

 developed, straight, rather thick exteriorly, arched above, and granulated laterally ; their 

 outer edge somewhat crenulated, granulose, slightly concave near the mural disc, and pro- 

 jecting a little towards the upper part. Pali well developed, very distinct from the septa, 

 and corresponding to those of the third cyclum. Height of the corallum, two or three lines ; 

 diameter, in general not more than five or six lines. 



This fossil is the only known species of the genus Cyclocyathus ; its form renders it 

 very remarkable. It has been found in the Gault at Cambridge, Drayton, West Mailing, 

 and Folkstone, but appears to be most abundant in the last-mentioned locality. The 

 specimens here described belong to the collections of the Geological Society, of Mr. 

 Bowerbank, and of Mr. D. Sharpe. 



3. Genus Trochocyathus (p. xiv). 

 1. Trochocyathus conulus. Tab. XI, fig. 5, 5 a. 



Caryophyllia contilus, (?) Phillips, Illust. of the Geol. of Yorkshire, tab. ii, fig. 1, 1829. 



(A rough figure -without any description.) 

 — — Michelin, Mem. de la Soc. Geol. de France, vol. iii, p. 98, 1838. 



Tukbinolia CONULUS, Michelin, Icon. Zooph., p. i, pi. i, fig. 12, 1840. 

 Trochocy'athcs conulus, Milne Edwards and J. Haime, Monogr. des Turbin., Ann. des 



Sc. Nat., 3 me serie, vol. ix, p. 306, 1848. 



Corallum simple, turbinate, rather elongate, straight or slightly bent, and pedicellated. 

 Wall presenting in general some slight traces of an incomplete epitheca. Costa simple, 

 distinct from the basis, closely set, delicately granulated, not very prominent, and alternately 



