To 



to-prove their animal nature. By the aid of a lens of moderate power 

 the central depression and projection are very plainly seen : and the 

 eye, thus assisted,, also discovers numerous thread-like processes, by 

 which these bodies are laterally connected. This curious conforma- 

 tion of these substances is still more distinctly observable, on the 

 inferior surface of this stone, which displays its fracture; it having 

 been evidently here separated by violence from the mass to which it 

 originally belonged. 



At Plate VIII. Fig. 12, is a magnified representation of five of 

 these bodies, by which, the frequent connection effected by means of 

 these filamentary processes will be distinctly seen. The bodies which 

 are here figured are connected by lateral filaments; but from the 

 marks which remain of attachment of similar filaments, on their supe- 

 rior surfaces, it is highly probable that these bodies were conected by 

 filaments, proceeding from several parts of their surface. Such an 

 arrangement of parts seems decidedly to determine that these bodies 

 are not, as might be supposed, merely calcareous concretions; but that 

 they have indubitably derived their existence from the regular opera- 

 tion of the laws of animal organization. 



The silicious pebble, Plate VIII. Fig. 10, which was found in the 

 Gravel-pits, near Hackney, had long been the subject of fruitless con- 

 jecture ; no circumstance being discoverable in its appearance, which 

 would determine its place in any classification, nor any analagous 

 body being recollected, by which its nature could be illustrated. By 

 its comparison with the preceding specimen, its analogy with it, ap- 

 pears to be indisputable. The whole fossil being of a calcedonic sub- 

 stance, possesses that degree of hardness which has rendered it but 

 little susceptible of injury from mechanical violence; and he^ice its 

 peculiarity of structure is still distinctly observable. 



In this specimen, as well as in another, from the Leverian Collec- 

 tion, the character of the original substance is plainly discoverable. 

 Small round compressed bodies, not exceeding an eighth of an inch. 



