f 
EXPLANATION OF PLATE 57. 97 
Fig. 5. Longitudinal Sections of Araucaria excelsa, 
shewing polygonal disks, in double and triple rows, 
on the surface of the longitudinal tubes. Some of 
the tubes arc without disks, as in all Coniferse. 
Fig. 6. Transverse Section of Araucaria cxcelsa. 
Portion of concentric annual layer. 
Fig. 7. Radiating and concentric structure of a branch 
of Pinus, as seen by the naked eye in a transverse 
section; the microscopic reticulations are omitted. 
(See V. I. p. 486. Note.) 
a. Concentric annual layers, indicating periodical 
growth. 
Fig. 8. Longitudinal Section of Pinus, shewing the rela- 
tive positions of the longitudinal vessels and me- 
dullary rays. 
Longitudinal vessels, forming the woody fibres. 
Medullary rays. 
Plate 57. V. I. p. 494. 
Sections exhibiting the silicified remains of Coniferm 
Cycadeae, in their native bed, between the Portland 
^nd Purbeck stone, on the coast of Dorsetshire. 
Fig- 1. Appearance of trunks and roots of large Coni- 
ferous trees, and of trunks of Cycadites, in the 
black earth, which formed the soil of an ancient 
^ Forest in the Isle of Portland. (De la Beche.) 
'g- 2. Remarkable concentric Ridges of Stone, around 
the erect stump of a Fossil Tree in the Isle of 
^ Portland. See V. I. p. 495. Note. (Henslow.) 
g- 3- Inclined position of the petrified stumps of large 
Coniferse, and of the bed of black mould and peb- 
bles ^in which they grew, near I.ul worth Cove, on 
the Coast of Dorset. (Buckland.) 
G. I 
I. 
H 
