nodules, but is evidently disposed between all the branches : and even 

 the spathose matter which has filled the cavities of the coral has 

 received a strong red tinge from the oxide of iron. A polished 

 section of this stone manifests this, and shews that if it could be ob- 

 tained in masses sufficiently large, it might from the closeness of its 

 texture be employed for many useful purposes. It is indeed a marble 

 of rather dull appearance ; but it would not be without its beauties, 

 since the little variety of colouring which it possesses is pleasingly 

 disposed, and would be somewhat enlivened by the stellated spots 

 yielded by the transverse sections of the coral. 



Madrepora fascicularis, a figure of which is given in Silesia Subter- 

 raneaVolkmanni. Tab. XVII. Fig. 14, is a fossil which possesses a very 

 distinguishing character ; the tubes of which it is formed almost always 

 shewing, in their longitudinal section, numerous transverse septa, as 

 may be seen in the small specimen, Plate VI. Fig. 11. This peculiar 

 appearance results from the following structure of this coral. It is 

 formed of slightly diverging, cylindrical tubes, which are so closely 

 beset by transverse septa, as scarcely to leave, sometimes, a space of 

 the sixteenth of an inch between them. The stars of this madrepore 

 are composed of about thirty radii or perpendicular lamellae ; half of 

 which reach, from the circumference, to about one third of the semi- 

 diameter from the centre, while the other scarcely extend one third of 

 the semidiameter from the circumference. Hence the centre of the 

 tubes, for one third of their diameter, are perfectly free from any 

 perpendicular laminae ; in the next space of one third, these perpen- 

 dicular laminae are but thinly placed; and it is only in the space next 

 the sides of the tubes that these lamina are fully disposed. In con- 

 sequence of this arrangement it is obvious, that a perpendicular sec- 

 tion, through nearly the centre of the coral, must in general display 

 the transverse septa only ; since in every longitudinal section they 

 must be divided and exposed, whilst the longitudinal lamella must 

 necessarily be partly concealed, even if the tubes are not filled with 



