69 



concentric rugae, disposed round a pedicle. The substance is generally 

 spathose. 



The structure of these bodies materially differs from that of any of 

 the fossil madrepores we have yet examined, as will be shewn by the 

 annexed figures. Plate VII. Fig. 4, represents the inferior surface, 

 in the centre of which is the pedicle, surrounded by alternate risings 

 and depressions. With this surface, the little artists appear to have 

 commenced their labours : this being the basis on which has been dis- 

 posed a curious plexus of tubuli investing tubes placed at regular 

 distances, whose edges are internally crenulated ; which latter circum- 

 stance is however only discoverable by the aid of a lens. Thus aided, 

 the eye discovers that the superior surface, Fig. 5, is generally beset 

 with very minute openings, which, occurring on the edge of larger 

 openings, occasion their edges to assume a crenulated, stellular form. 

 The section, Fig. 2, shews the tubes, originating at the inferior surface, 

 divided into separate chambers by transverse lamellae, and thus pro- 

 ceeding to the superior surface. These fossils are found in Gloucester- 

 shire, Staffordshire, and in many parts of England. 



At Plate VII. Fig. 3, is the representation of the under surface 

 of a very curious fossil coral from Dudley in Staffordshire, which may 

 be considered as a variety of this species. The difference chiefly con- 

 sists in the diverging striae, on the under part, being considerably larger 

 and more distinct ; and in the cavities, on the superior surface, being 

 polygonal, and forming an honey-comb surface, as represented in 

 outline at Fig. 7- 



Plate VII. Fig. 10, is a specimen of the compound turbinated ma- 

 drepore. This, like the former, is composed of crenulated tubes, sur- 

 rounded by a plexus of tubuli, which open on the general superior 

 surface, and which, by the regular arrangement of their terminations 

 round the openings of the tubes, gives to them a stellated form. In 

 this fossil the labours of the polypes have commenced at the pedicle, 

 and one area having been completed, another has been formed over 



