Dr. FiTTON on the Strata below the Chalk. 175 



figs. 2 and 9, the extremity is more acute than in the greater number of the 

 specimens. In a few instances (as in fig. 8, and less obviously in figs. 2, 

 and 1,) the nucleus seems to have been suddenly r^educed in thickness near 

 the broader end ; but no specimen of this form was observed in situ. None of 

 the specimens exhibited the tapering figure, somewhat like that of a ninepin, 

 represented in the engraving in the Geological Transactions*; but many of 

 the broken and worn fragments washed up on the shore near the White Rock 

 had acquired some approach to that form. There was not, in any of the spe- 

 cimens, the slightest indication of lateral branches from the main body ; but 

 they all lay as if they had been distributed without connexion in the stratum 

 in which they were found. 



(88.) The coaly covering did not, in any instance, show traces of or- 

 ganic structure ; it burned with a slight flame when thrown upon hot coals, 

 and in the flame of a candle became white, and was reduced in bulk without 

 losing its form. In some of the fresh specimens it was coated with a thin 

 crust, of a light brownish or drab colour, with a very slight glistening lustre ; 

 apparently consisting of compressed clay. This is represented especially in 

 figs. 4, a and 6, and partiaHy shown in figs. 3 and 8. 



(89.) The internal structure of this fossil has been partially described and 

 represented in the Geological Transaction s+, by the Secretaries and a Com- 

 mittee of the Members. I am enabled to add some further particulars to 

 what is there stated, through the kindness of my friends Mr. Brown and 

 Mr. Stokes : the former having lent me the specimen represented in Plate 

 XX., fig. 3., and given directions for making the slices, figs. 1. and 2.; to 

 which Mr. Stokes was so good as to add a very thin slice, represented in figs. 

 4. and 4. a. The vermicular cavities or tubes, of which a longitudinal section 

 is represented in fig. 1., and a transverse section in fig. 2, and 4., are all coated 

 within with transparent quartz crystals, the summits of which are discernible 

 with a lens ; and in some cases the cavity of these tubes was partially oc- 

 cupied by exceedingly minute crystals of quartz, either detached in the 

 state of sand, or intermixed with a flocculent coaly matter. The transverse 

 sections of these tubular cavities exhibit a similar change of form, from circular 

 to elliptic, to that shown by the entire plant. In the greater number of cases 

 no trace of truly organic conformation could be detected with the microscope 

 in these sections; but in two specimens a distinct indication of the original 

 vegetable structure was to be seen. These are represented in Plate XX., figs. 

 3. and 4. The former figure, drawn from the extremity of a solid and opake 



* Second Series, vol. i. Plate 48. 



t Second Series, vol. i. Plates 46 and 47 : and Mantell, Tilgate Fossils, Plates 2 and 3. 



