152 



XII. Fig'. 8, is an interesting fossil; terminating, at the lower end, in 

 a point, from which the pedicle proceeded, and having in its supe- 

 rior part, the opening into its larger cavity, and on its sides the nume- 

 rous openings, in which its peculiar hydrae had their residence. 



I must once more observe, before I quit the fossils of this family, 

 that I have, in several instances, classed as alcyonia, bodies, which 

 appear , in some respects, rather to accord with the genus doris, ascidia, 

 or actinia; but which, in their general characters, differ so widely 

 from any of these bodies with which we are at present acquainted, as 

 to prevent their being placed under any existing genus. Here, 

 perhaps, they had better remain, until more illustrative specimens 

 shew their real nature, and the genus to which they more properly be- 

 long. 





LETTER XVI. 



NCRINITES AND PENTACRINITES....TROCHITES... HISTORY OP.. .VA- 

 RIOUS SPECIES DESCRIBED. ...ORIGINAL ANIMAL MEMBRANE DE- 

 MONSTRATED.. ..SCREW-STONE. 



WE shall now proceed to the examination of a series of animals, 

 which, whether we consider their extraordinary forms, the immense 

 numbers in which they must have existed, in a living state, in the for- 

 mer world; or their being now, except in a solitary instance or two, 

 to be traced only by their petrified remains, under the surface of the 

 earth, or on the summits of mountains, undoubtedly offer to us as 

 rich a field of observation as the most arduous inquirer could wish to 

 explore, 



