OF THE FOSSIL PLANTS OF THE COAL-MEASURES. 
25 
Plate 6. fig. 28. Transverse section of the outermost cortical layers, showing the double 
row of epidermal cells. Enlarged 200 diameters. 
Plate 4. fig. 29. Radial longitudinal section of a matured stem passing through two 
vascular laminae at e and e\ with the mural cells of the medullary 
ray separating the laminae at f,f. Enlarged 130 diameters. 
Plate 6. fig. 30. Tangential section of a matured stem intersecting the central vascular 
exogenous wedge ( d ) near the medullary vascular axis, the two 
more external ones ( d d") being intersected a little obliquely and 
nearer to their peripheral extremities, as in fig. 27. The centripetal 
cortical parenchyma separating the three vascular wedges is seen at 
h, h . Enlarged 65 diameters. 
,, fig. 31. Transverse section of the peripheral portion of the vaspular wedge of a 
matured stem, exhibiting several vascular laminae ( e , e ) separated by 
medullary rays and showing new vessels (e\ e") forming in the 
pseudo-cambial layer ( g , g). Enlarged 130 diameters. 
„ fig. 32. Transverse section of a matured stem deprived of its outermost bark, 
but detaching laminae of vessels at x from the vascular wedge to the 
right of the cortical lamina (//) preparatory to the formation of a 
branch. Enlarged 30 diameters. 
„ fig. 33. Transverse section of the same stem as fig. 32, but made a little higher 
up than that section. The branch has here attained a semicylindrical 
form, pushing aside the two vascular wedges (c 1 , c"), and has definite 
medullary rays (f,f) separating its radiating vascular laminae. En- 
larged 40 diameters. The pseudo-cambial masses are seen at g, g. 
Enlarged 30 diameters. 
Plate 7. fig. 34. A third transverse section of the same stem made a little higher up than 
fig. 33. The branch has now attained its cylindrical form and become 
entirely free from the wedges (</, c"), which have returned to nearly 
their normal positions. The vascular laminae of the branch exhibit 
a tendency to arrange themselves into groups corresponding to the 
primary wedges of the parent stem. Enlarged 30 diameters. 
„ fig. 35. Tangential section of two primary vascular wedges (d, d'), with a vas- 
cular bundle (y) passing outwards through the intervening cortical 
parenchyma ( h ). Enlarged 48 diameters. 
„ fig. 36. Obliquely tangential section of the cortical portion of the stem (fig. 1), 
showing a vascular bundle (y) like that of fig. 35, passing outwards 
through the outer cortical layer (*'). Elongated examples of the 
epidermal cells seen at Jc. Enlarged 48 diameters. 
„ fig. 37. Section of a very small vascular axis, with but five primary wedges. 
Enlarged 80 diameters. 
„ fig. 38. Similar section to the last, but with four primary wedges. Enlarged 
80 diameters. 
MDCCCLXXVI. 
