266 
PROFESSOR W. C. WILLIAMSON ON THE ORGANIZATION 
Fig. 46. Transverse section of a small branch of a Dadoxylon, exhibiting concentric 
lines of growth. Enlarged diameters. 
g, g. Pairs of leaf-bundles. 
Fig. 47. Portion of a radial section of the specimen fig. 44, exhibiting a foliar bundle {V) 
departing from the innermost layer of the woody zone. Enlarged 15 
diameters. 
a , a. Thickened outermost margins of the Sternbergian medullary disks. 
Fig. 48. Tangential section of a portion of the ligneous zone of fig. 44, exhibiting two 
of the foliar bundles (g, g) intersected transversely, b. Vessels of the ligneous 
zone. Enlarged 15 diameters. 
Fig. 49. Tangential section of a portion of the ligneous zone of the Coalbrookdale twig 
(figs. 33-40), exhibiting some of the fibres undergoing deflection to form a 
foliar (X) bundle. Enlarged 62^ diameters. 
f,f. Medullary rays. 
Fig. 50. Part of the radial section of a Dadoxylon from Binns Cliff, Burntisland. En- 
larged 62^ diameters. 
Fig. 51. Part of a wood-fibre of fig. 50, showing the surface parallel to the medullary 
rays. Enlarged 270 diameters. 
Fig. 52. Part of a fibre, showing the surface parallel to the medullary rays, from 
Oldham. Enlarged 270 diameters. 
Seeds of Gymnospermce. 
Fig. 53. lagenostoma ovoides. Obliquely transverse section through the upper extremity 
of the micropyle of Mr. Butterworth’s specimen. 
a. Exotesta, d. Orifice of lagenostome. e. Part of the “ canopy ” of the 
lagenostome. 
Fig. 54. Second section of the same specimen made a little below the apex of the seed. 
a. Exotesta, c. Lagenostome. e. Folds of canopy. 
Figs. 55 & 56. Third and fourth sections of the same, made yet lower down. 
Fig. 57. Portion of the testa (a) and canopy ( e ), from a section intermediate between 
figs. 55 & 56. 
Fig. 58. Tangential section of a second seed of Lagenostoma ovoides , made midway 
between its centre and its lateral surface. 
a. Testa, f. Nucular membrane, g. Perispermic membrane. Enlarged 
15 diameters. 
Fig. 59. Second tangential section of fig. 58, made nearer to its centre. 
a. Testa, c. Lagenostome. e, e. Canopy, f. Nucular membrane, g. Peri 
spermic membrane, h. Parenchyma of the interior of the lagenostome. 
Enlarged 15 diameters. 
Fig. 60. Vertical section made through the centre of fig. 58. 
a. Testa, c. Lagenostome. d. Micropyle. e, e. Canopy, f. Nucular 
