ILLUSTRATED BY FIGURES. 39 
Fig. 7. Portion of a transverse slice of a fossil plant found at Allanbank 
Mill, near the junction of the Whitadder and Blackadder. This plant is 
externally roundish, and tapering. Its transverse section displays an irre- 
gular texture, intersected and distorted by calcareous spar. In some places 
are indistinct appearances of medullary rays, but there are no concentric 
layers. The cells toward the margin are very regular, more or less hexa- 
gonal, in series converging toward the centre, but broken up by the crystal- 
lizations, which assume various beautiful forms, as represented in the upper 
part of the figure. 
Fig. 8. Attached to the roundish part, is an regular darker coloured 
substance, apparently confused, but exhibiting a regular structure in various 
places, and having interspersed in it numerous oval forms, of part of one of 
which this figure is a representation. These oval forms very much resemble 
the pithy part of some dicotyledonous plants, as well as the stipe of various 
ferns. Ihave not, however, satisfied myself as to their real nature, and 
therefore cannot venture upon any opinion respecting them. 
Fig. 9. Represents a portion of the Lennel Braes fossil, figured in 
Plates I. and III. The fragment of organic structure at the upper corner 
is silicified, and very regular. It presents the appearance of a line of junc- 
tion between two concentric layers. This figure is of the natural size. 
Fig. 10. The margin of the fragment indicated above, enlarged about 
fifty-five times. This figure displays the beautiful lace-like structure, broken 
up at the edge by calcareous spar, of which two divergent crystallizations 
are seen. This specimen shews very distinctly that the large cellular por- 
tions of the fossil in question are merely crystallizations, and not regular 
texture. 
Fig. 11. Fossil silicified dicotyledonous wood, from Antigua, enlarged 
about fifty-five times. The structure greatly resembles that of the maho- 
gany, represented in Plate I. Fig. 7. 
Fig. 12. Fossil silicified dicotyledonous wood, from Antigua, enlarged 
about fifty-five times. 
Fig. 13. Fossil silicified dicotyledonous wood, from Antigua, enlarged 
