93 



spongy part of alcyonia, whilst the intervening spaces appeared to be 

 filled by a softer substance, a carbonate of lime. The substance was 

 therefore partly immersed in dilute muriatic acid, by which the cal- 

 careous part was speedily removed, with effervescence, and the sili- 

 cious part left, possessing the fine retiform texture of the spongy alcy~ 

 oniuin, surrounding the central opening already mentioned, as may 

 be seen in the upper part of the figure. 



The fossil represented Plate VII. Fig. 9 approaches the nearest, in 

 its general form and appearance, to the alcyonium cydonium Linnsei, 

 the alcyonium primurn of Dioscorides, or rather to the representation of 

 this animal as given by Donati. It must however be, I believe, con- 

 sidered, as differing from any known animal of this genus. 



This fossil is of a roundish form, rendered unequal by shallow de- 

 pressions about the width of a finger, which pass from the superior to 

 the inferior part of the fossil, and are separated from each other by 

 tuberculated ridges. At the upper part has been a circular opening 

 more than half an inch in diameter; and, at the lower part, is a rugged 

 spot as though the pedicle had been here separated : a circumstance 

 indeed which renders its affinity to the alcyonium described by Donati 

 rather more doubtful. The substance of this fossil appears to be a lime- 

 stone which, probably from some tinge of iron, has obtained a reddish 

 brown colour. It is not of a very close texture, apparently from the 

 superadded calcareous matter not having accurately filled all the in- 

 terstices between the fibres. Hence numerous small openings are, 

 even in its present state, observable on its surface, which on close in- 

 spection are seen ta be such as would result from a loose or spongy 

 texture. 



Whilst treating of the alcyonium, of the species to which this seems 

 to approach, Donati particularly describes and delineates the curiously 

 formed spiculae which constitute a part of its substance. The body, 

 as well as the cortical part, he remarks, is formed of two substances: 



