ILLUSTRATED BY FIGURES. 35 
timate a resemblance between plants belonging to epochs so remote from 
each other. 
PLATE V. 
FOSSIL VEGETABLES OF THE LIAs,—continued. 
THE figures represent portions of thin transverse slices, viewed by trans- 
mitted light, and uniformly enlarged in the proportion of 55 to 1, excepting 
Fig. 6. which is of the natural size. 
Fig. 1. Portion of a transverse section of fossil wood from the upper 
lias, near Whitby, to the south. This wood is in concentric layers, which, 
viewed by transmitted light, are umber-brown. The layers are separated 
by calcareous spar, so as to present a broken and confused appearance. ‘The 
portion represented is one of the most regular, being from near the margin, 
where the layers are occasionally contiguous. 
Fig. 2. This figure represents part of five layers near the centre of the 
same fossil. The irregular interruptions of the structure are filled with calca- 
reous spar, and are not lacune, of which there are no traces in the regular 
portions. One of the most remarkable circumstances in the organization of 
this fossil, is the great difference in the breadth of the woody layers. An- 
other is the difference in the texture, Fig. 1. presenting distinct medullary 
rays, while Fig. 2. wants them, being from a portion in which they are not 
observed. Fig. 1. also appears very different from Fig. 2. in the size and 
form of the cellules, but this difference arises solely from the circumstance 
that the former is from a thicker portion of the slice, similar differences in 
thickness producing corresponding differences in appearance, in the slices of 
recent plants. 
Fig. 3. Portion of a slice of recent wood from the lias, near Whitby. 
In this wood, the concentric layers are very distinct, although, in some places, 
E2 
