42 BRITISH FOSSIL CORALS. 



the upper surface of the ccenenchyma which separates them ;^ their margins are sharp, the 

 fossa is shallow, and the columella rudimentary. 



The septa are thin and well marked ; they form six systems, and there are four cycles. 

 Tire primary, secondary, and tertiary septa are very much alike, and extend well towards 

 the centre of the calice. The septa of the fourth and fifth orders are short, and do not 

 extend far from the wall.^ 



The columella is rudimentary, and consists of a few processes derived from the inner 

 margins of the septa. It is made to appear larger than it really is, by the frequent deve- 

 lopment of the endotheca near the inner septal margins. In some calices it appears as if 

 one of the larger septa crossed over the columellary space, and became connected to the 

 opposite one. 



The endotheca is greatly developed ; the dissepiments incline so much that transverse 

 sections of corallites or worn calices show numerous transverse bars between the septa :' 

 really these bars are but sections of oblique dissepiments. 



The costae, when covered by the exotheca, are rudimentary, and exist as faint unequal 

 ridges which are slightly raoniliform ; but where they are above the ccenenchyma, and 

 close to the calicular margin, they are feebly developed, but distinct, unequal, alternately 

 large and small, and bluntly dentate.* 



The exotheca is abundant, and consists of small square cells, rectangular cells, and of 

 a tissue in which the cells form a dense ccenenchyma.^ It passes from corallite to 

 corallite, and is marked on its upper or free surface by faint ovoid and rather flat ele- 

 vations, which are close in some places but distant in others.* The upper layer of 

 the exotheca often grows up the sides of the corallites to the calices. 



Height of corallum ^th inch. Diameter of corallites f^tli inch (in the largest). 



Locality. — Brockenhurst. In the Museum of Practical Geology, London. 



2. SoLENASTRiEA KoENENI, DuncaU. PI. V, figS. 8, 9. 



The corallum is short, gibbous, and irregular. 



The corallites are rather but unequally distant from one another. The calices are 

 hardly exsert, and are very shallow and open. There are no costse visible, and a continuation 

 of the ccenenchyma upwards reaches the calicular margin.' 



The septa are in six systems and there are four cycles. The septa are thin, delicate, wide 

 apart, unequal, and occasionally not quite straight.** 



1 Plate V, fig. 1. - Plate V, figs. 3, 4. » Plate V, fig. 3. 



" Plate V, figs. .5, 6. '■> Plate V, figs. 2, 5. ^ Plate V, fig. 7. 



7 Plate V, fig. 8. 8 Plate V, fig. 9. 



