526 
PROFESSOR W. C. WILLIAMSON ON THE ORGANIZATION 
Fig. 4. Central vascular axis of fig. 3 enlarged 14 diameters. a. Vascular 
medullary cylinder. a'. Vessels going off radially to form the free 
foliar bundles, c. d. Cellular medulla. 
Fig. 5. Transverse section of a still larger branch, a. Vascular medullary cylinder. 
d. Cellular medulla, e. Middle bark corresponding to e of fig. 3. 
g. Inner portion of prosenchymatous bark. h. Bast-layer of outer bark. 
i. Exogenous layer of vascular axis. Three-fourths the natural size. 
Fig. 6. Transverse section of the vasculo-medullary axis of a stem of large size. 
a. Vascular medullary cylinder, d. Medulla, i. Enlarged exogenous 
vascular cylinder. Natural size. 
Fig. 6a. Segment of a section like fig. 6 enlarged 3 diameters. 
Fig. 7. One of the rhomboidal scars of a cast of the outer bark-surface of a large 
stem. Three-fourths the natural size. 
PLATE 15. 
Halifax Lycopodiacece. 
Fig. 8. Small crushed Lepidostrobus from Halifax enlarged nearly 12 diameters. 
a. Vasculo-cellular axis. b. Clusters of macrospores, c. Upper part 
of the strobilus. d. Clusters of microspores in their sporangia. 
Fig. 9. Sporangial cluster of four macrospores, showing that the “peduncular 
appendages” are but collapsed portions of the spores. Enlarged 34 
diameters. 
Fig. 10. Tangential section of a sporangiferous bract from Halifax, with its sporan¬ 
gium filled with microspores, a. Bract. b. Outer sporangium-wall, 
c. Inner membrane of the sporangium. Enlarged 45 diameters. 
Fig. 11. Transverse section of the central axis of the strobilus figured in Plate 
22, fig. 53, of memoir, Part IX. a. Medulla. b. Vascular cylinder. 
c. Innermost cortical parenchyma. d. Outer cortical parenchyma. 
e. Bracts, f Sporangia. Enlarged 12 diameters. 
Fig. 12. Central axis of fig. 11, enlarged 45 diameters, a. Medulla, b. Vascular 
cylinder, c. Badial breaks in the continuity of the cylinder, d. Inner¬ 
most cortical layer, d'. Badial prolongations of d, apparently accom¬ 
panying vascular bundles proceeding outwards to the bracts. 
Fig. 12a. Transverse section of a pentamerous fruit (?) from Halifax. 
Calamostachys Binneyana. 
Fig. 13. Longitudinal section of a specimen of Calamostachys Binneyana from 
Halifax, a. Vascular axis. b. Cortical layer of the axis. c. Sterile 
bracts, cl. Fertile bracts or sporangiophores. cl', cl". Empty passages 
