412 OK THE FORMATION OF THE CHALK STRATA, 



No. 4. This beautiful specimen resembles the first I obtained. 

 Along side of the cone are those tubes and capillary vessels 

 connected with the cone, and with the sides of the belem- 

 nite, and entangled in lace-like work, small, irregular, glo- 

 bular masses, all connected by the most slender fibres. 



No. 5. In this specimen the fossil is inverted, the base of the 

 cone being uppermost. In order to prevent it from falling 

 to pieces, the dissolution of the carbonate was watched, 

 and stopped, when the specimen was sufficiently displayed ; 

 it will be seen how much the vessels which have here exist- 

 ed, have the character of organization ; they twist and range 

 about, quite like the gut of an animal. Still, as we see so 

 little resemblance between this and the other specimens, we 

 cannot but hesitate to attribute it to an origin which be- 

 speaks uniformity and regularity. 



No. 6. Plate XXVI. This specimen is singular ; it has evidently 

 been broken off at each end ; the cone, of which only a small 

 portion remains, rests upon flint, which is impressed with the 

 radiated structure of the fossil, and the upper part is broken 

 off at right angles, showing not only that it must have been 

 a fragment of the belemnite, when originally inclosed in the 

 flint, but also that it was then possessed of the same radi- 

 ated structure it now presents. Hence, if it be a petrifaction, 

 in place of an original formation, as I have been led to con- 

 sider it, it must have been transformed previous to its inclo- 

 sure in the flint. Upon the surface small branches of arbo- 

 rescent flint may also be observed, as if the original had 

 been covered with some delicate conferva, now converted 

 into silex. There are also some of those cylindrical branches 

 very short, as if they had occupied only the commencement 

 of the perforation, which have proceeded from the surface 

 inwards, without the appearance of fracture at the extremi- 

 ties, 



