358 PKOFESSOE W. C. WILLI^iMSON ON STERNBERG I-E. 



INDEX TO THE PLATES OF THE ABOVE PAPER. 



Fig. 1. Fragment of wood from Coalbrookdale, fractured longitudinally ; 

 a and b, bark: c, woody zone; g, medulla; h, cast of hollow 

 pith, or Sternbergia. 



2. Transverse section of the same fragment. The same letters are 



employed as in fig. 1. 



3. Transverse section of the bark ; a, Epiphloeum and Mesophloeum ; 



b, Endophloeum ; c, Pleurenchyma, or woody fibre. 



4. Vertical section of the bark ; a, Epiphloeum and Mesophlojum ; 



6, Endophloeum ; c, Pleurenchyma. 



5. Transverse section of the woody zone and pith ; c, Pleurenchyma ; 



d, medullary rays ; ff, medulla. 



6. Vertical section of the same portions as fig. 6 ; c, Pleurenchyma ; 



d, medullary rays ; ff, medulla. 



7. Fibres of Pleurenchyma from fig. 6, still more highly magnified, 



and exhibiting the hexagonal disks. 



8. Vertical section of the Pleurenchyma, parallel with the bark, and 



at right angles to the medullary rays; «, transverse bars 

 marking the positions of the disks ; d, intersected medullary 

 rays. 



9. Small portion of fig. 8 still more highly magnified. 



10. Specimen of Sternbergia from the Lancashire coal field ; c, 



woody zone ; g, pulverulent carbonaceous matter, representing 

 the medulla ; /*, cast of medulla, or Sternbergia approximata. 



11. Vertical section of restored medulla of Dadoxylon (Sternbergia) 



approximatum ; c, woody zone ; g, medulla ; A, cast of medullary 

 cavity. 

 12 Vertical section of a young branch of Gary a angustif olia, or hickory j 

 a, bark ; b, wood ; c, pith ; d, hollow cavities. 



