AJitMAL MATTER IN *6SSILS* S25 



taehed, and slowly sunk to the bottom of the glass. The 

 smallness of the pieces of membrane might be here pro- 

 bably accounted for by the structure of the madreporite 

 which they composed ; since from the multitude of pores 

 with which it is pierced, the membrane must suffer such 

 frequent inflexion, as would give very little reason to expect, 

 that, in a corroded preparation of even the recent madre- 

 pore, any thing like the form of the madrepore could be 

 preserved. The circumstance of these membranous floccuii 

 appearing to possess a greater degree of gravity than belongs 

 to animal membrane in general may be accounted for, by 

 considering, that they may yet retain some particles of earth 

 in some of their cavities, which are defended from the ac- 

 tion of the acid, by being completely enclosed in the mem- 

 brane. 



A small, light coloured, calcareous spongite, or alcyonite, A very perfect 



possessing somewhat of a conical form and a rugose surface, membrane ob- 



, . . tamed from * 



and exhibiting, when examined with a lens, evident marks spongite. 



of an original spongeous substance, was suspended in water 

 slightly acidulated with muriatic acid. As the acid acted 

 on the carbonate of lime, the membraneous part of the 

 sponge began to appear; and being liberated, extended 

 itself beyond the remaining solid mass in tolerably cohe- 

 rent flexible floccuii. When it had been submitted so 

 long to the action of the acid, that the carbonate of lime 

 was nearly removed, a dark brown reticulate mass was left, 

 bearing the general form of the fossil, and manifesting its 

 original spongeous reticulated texture. So coherent was 

 this mass, us even to l^ear its removal, by pouring into an- 

 other glass, without suffering any material injury to its form. 

 It was however at last broken, upon pouring additional wa-i 

 ter into the phial which contained it. Another specimen, as si- 

 milar in its form and size as could be found, was then sub- 

 jected to the action of the acid for the purpose of ob- 

 taining a correct sketch of the remaining membrane, and 

 with equal success. 



IX. 



