1F0SSIL ALCYONIA. 47 



blance to alcyonium digitatum of Linnaeus j or the deadmaiis 

 hand, or dead man's toes of Ellis. Its texture evidently ap- 

 pears to be of that kind, being finely reticulated, which 

 would correspond with the carneous spongy substance, of 

 which the recent zoophyte is formed. Its surface also, 

 thickly beset with minute openings, bearing somewhat of a 

 stellated appearance to the naked eye, serves to confirm the 

 resemblance. This fossil is now a carbonate of lime mode- Chalk. 

 rately hard, but friable. 



In the elegant work of Mr. Knorr, Mr* Walsh describes Priapolithi. 

 several fossil elongated alcyonia, by the silly term which 

 the ancients had adopted, of priapolithu One of these from 

 Touraine is figured, Plate VII, fig. 1. It had at its su- 

 perior termination that opening, observable in many of 

 these animals, which served for the reception of the sea- 

 water, from which, it is probable, they derived their sup- 

 port. 



On rubbing down this substance on a sandstone, at this A retiform tex- 

 termination, for the purpose of examining its structure r its tureof sJex -> 

 hardness and the partial polish it obtained, proved, that it 

 had suffered an impregnation with silica: and an examina- 

 tion of this surface with a lens plainly showed, that the 

 flinty part was regularly distributed in continuous mean- 

 dering lines, bearing the peculiar and characteristic form 

 of the 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 di- and the int^i- 

 lute muriatic acid, by which the calcareous part was speedily st !^ s ?H^ 

 removed, with effervescence, and the siliceous part left, pos- 

 sessing the fine retiform texture of the spongy alcyonium, 

 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 

 cydoninm Linnsei, the alcyonium primum of Discorides, or 

 rather to the representation of this animal as given by Do- 

 nati. It must however be, 1 believe, considered, as differ- 

 ing from any known animal of this genus. 



This fossil is of a roundish form, rendered unequal by 

 shallow depressions about the width of a finger, which pass 



from 





